get.py

import uuid
import logging
import json

from pylons import config
from pylons.i18n import _
import webhelpers.html
import sqlalchemy

import ckan
import ckan.authz
import ckan.lib.dictization
import ckan.lib.base
import ckan.logic as logic
import ckan.logic.action
import ckan.lib.dictization.model_dictize as model_dictize
import ckan.lib.navl.dictization_functions
import ckan.model.misc as misc
import ckan.plugins as plugins
import ckan.lib.search as search
import ckan.lib.plugins as lib_plugins

log = logging.getLogger('ckan.logic')

# Define some shortcuts
# Ensure they are module-private so that they don't get loaded as available
# actions in the action API.
_validate = ckan.lib.navl.dictization_functions.validate
_table_dictize = ckan.lib.dictization.table_dictize
_render = ckan.lib.base.render
Authorizer = ckan.authz.Authorizer
_check_access = logic.check_access
NotFound = logic.NotFound
ValidationError = logic.ValidationError
_get_or_bust = logic.get_or_bust

_select = sqlalchemy.sql.select
_aliased = sqlalchemy.orm.aliased
_or_ = sqlalchemy.or_
_and_ = sqlalchemy.and_
_func = sqlalchemy.func
_desc = sqlalchemy.desc
_case = sqlalchemy.case
_text = sqlalchemy.text

def _package_list_with_resources(context, package_revision_list):
    package_list = []
    model = context["model"]
    for package in package_revision_list:
        result_dict = model_dictize.package_dictize(package,context)
        package_list.append(result_dict)
    return package_list

def site_read(context,data_dict=None):
    '''Return ``True``.

    :rtype: boolean

    '''
    _check_access('site_read',context,data_dict)
    return True

def package_list(context, data_dict):
    '''Return a list of the names of the site's datasets (packages).

    :rtype: list of strings

    '''
    model = context["model"]
    api = context.get("api_version", 1)
    ref_package_by = 'id' if api == 2 else 'name'

    _check_access('package_list', context, data_dict)

    query = model.Session.query(model.PackageRevision)
    query = query.filter(model.PackageRevision.state=='active')
    query = query.filter(model.PackageRevision.current==True)

    packages = query.all()
    return [getattr(p, ref_package_by) for p in packages]

def current_package_list_with_resources(context, data_dict):
    '''Return a list of the site's datasets (packages) and their resources.

    The list is sorted most-recently-modified first.

    :param limit: if given, the list of datasets will be broken into pages of
        at most ``limit`` datasets per page and only one page will be returned
        at a time (optional)
    :type limit: int
    :param page: when ``limit`` is given, which page to return
    :type page: int

    :rtype: list of dictionaries

    '''
    model = context["model"]
    if data_dict.has_key('limit'):
        try:
            limit = int(data_dict['limit'])
            if limit < 0:
                limit = 0
        except ValueError, e:
            raise logic.ParameterError("'limit' should be an int")
    else:
        limit = None
    page = int(data_dict.get('page', 1))

    _check_access('current_package_list_with_resources', context, data_dict)

    query = model.Session.query(model.PackageRevision)
    query = query.filter(model.PackageRevision.state=='active')
    query = query.filter(model.PackageRevision.current==True)

    query = query.order_by(model.package_revision_table.c.revision_timestamp.desc())
    if limit is not None:
        query = query.limit(limit)
        query = query.offset((page-1)*limit)
    pack_rev = query.all()
    return _package_list_with_resources(context, pack_rev)

def revision_list(context, data_dict):
    '''Return a list of the IDs of the site's revisions.

    :rtype: list of strings

    '''
    model = context['model']

    _check_access('revision_list', context, data_dict)

    revs = model.Session.query(model.Revision).all()
    return [rev.id for rev in revs]

def package_revision_list(context, data_dict):
    '''Return a dataset (package)'s revisions as a list of dictionaries.

    :param id: the id or name of the dataset
    :type id: string

    '''
    model = context["model"]
    id = _get_or_bust(data_dict, "id")
    pkg = model.Package.get(id)
    if pkg is None:
        raise NotFound

    _check_access('package_revision_list',context, data_dict)

    revision_dicts = []
    for revision, object_revisions in pkg.all_related_revisions:
        revision_dicts.append(model.revision_as_dict(revision,
                                                     include_packages=False,
                                                     include_groups=False))
    return revision_dicts


def related_show(context, data_dict=None):
    '''Return a single related item.

    :param id: the id of the related item to show
    :type id: string

    :rtype: dictionary

    '''
    model = context['model']
    id = _get_or_bust(data_dict, 'id')

    related = model.Related.get(id)
    context['related'] = related

    if related is None:
        raise NotFound

    _check_access('related_show',context, data_dict)

    schema = context.get('schema') or ckan.logic.schema.default_related_schema()
    related_dict = model_dictize.related_dictize(related, context)
    related_dict, errors = _validate(related_dict, schema, context=context)

    return related_dict


def related_list(context, data_dict=None):
    '''Return a dataset's related items.

    Either the ``id`` or the ``dataset`` parameter must be given.

    :param id: id or name of the dataset (optional)
    :type id: string
    :param dataset: dataset dictionary of the dataset (optional)
    :type dataset: dictionary

    :rtype: list of dictionaries

    '''
    model = context['model']
    session = context['session']
    dataset = data_dict.get('dataset', None)

    if not dataset:
        dataset = model.Package.get(data_dict.get('id'))

    if not dataset:
        raise NotFound

    _check_access('related_show',context, data_dict)

    relateds = model.Related.get_for_dataset(dataset, status='active')
    related_items = (r.related for r in relateds)
    related_list = model_dictize.related_list_dictize( related_items, context)
    return related_list


def member_list(context, data_dict=None):
    '''Return the members of a group.

    The user must have permission to 'get' the group.

    :param id: the id or name of the group
    :type id: string
    :param object_type: restrict the members returned to those of a given type,
      e.g. ``'user'`` or ``'package'`` (optional, default: ``None``)
    :type object_type: string
    :param capacity: restrict the members returned to those with a given
      capacity, e.g. ``'member'``, ``'editor'``, ``'admin'``, ``'public'``,
      ``'private'`` (optional, default: ``None``)
    :type capacity: string

    :rtype: list of (id, type, capacity) tuples

    '''
    model = context['model']
    user = context['user']

    group = model.Group.get(_get_or_bust(data_dict, 'id'))
    obj_type = data_dict.get('object_type', None)
    capacity = data_dict.get('capacity', None)

    # User must be able to update the group to remove a member from it
    _check_access('group_show', context, data_dict)

    q = model.Session.query(model.Member).\
            filter(model.Member.group_id == group.id).\
            filter(model.Member.state    == "active")

    if obj_type:
        q = q.filter(model.Member.table_name == obj_type)
    if capacity:
        q = q.filter(model.Member.capacity == capacity)

    lookup = {}
    def type_lookup(name):
        if name in lookup:
            return lookup[name]
        if hasattr(model, name.title()):
            lookup[name] = getattr(model,name.title())
            return lookup[name]
        return None

    return [ (m.table_id, type_lookup(m.table_name) ,m.capacity,)
             for m in q.all() ]

def group_list(context, data_dict):
    '''Return a list of the names of the site's groups.

    :param order_by: the field to sort the list by, must be ``'name'`` or
      ``'packages'`` (optional, default: ``'name'``)
    :type order_by: string
    :param groups: a list of names of the groups to return, if given only
        groups whose names are in this list will be returned (optional)
    :type groups: list of strings
    :param all_fields: return full group dictionaries instead of  just names
        (optional, default: ``False``)
    :type all_fields: boolean

    :rtype: list of strings

    '''
    model = context['model']
    api = context.get('api_version')
    groups = data_dict.get('groups')
    ref_group_by = 'id' if api == 2 else 'name';
    order_by = data_dict.get('order_by', 'name')
    if order_by not in set(('name', 'packages')):
        raise logic.ParameterError('"order_by" value %r not implemented.' % order_by)
    all_fields = data_dict.get('all_fields',None)

    _check_access('group_list', context, data_dict)

    query = model.Session.query(model.Group).join(model.GroupRevision)
    query = query.filter(model.GroupRevision.state=='active')
    query = query.filter(model.GroupRevision.current==True)
    if groups:
        query = query.filter(model.GroupRevision.name.in_(groups))

    if order_by == 'name':
        sort_by, reverse = 'name', False

    groups = query.all()

    if order_by == 'packages':
        sort_by, reverse = 'packages', True

    group_list = model_dictize.group_list_dictize(groups, context,
                                    lambda x:x[sort_by], reverse)

    if not all_fields:
        group_list = [group[ref_group_by] for group in group_list]

    return group_list

def group_list_authz(context, data_dict):
    '''Return the list of groups that the user is authorized to edit.

    :param available_only: remove the existing groups in the package
      (optional, default: ``False``)
    :type available_only: boolean

    :returns: the names of groups that the user is authorized to edit
    :rtype: list of strings

    '''
    model = context['model']
    user = context['user']
    available_only = data_dict.get('available_only',False)

    _check_access('group_list_authz',context, data_dict)

    query = Authorizer().authorized_query(user, model.Group, model.Action.EDIT)
    groups = set(query.all())

    if available_only:
        package = context.get('package')
        if package:
            groups = groups - set(package.get_groups())

    return [{'id':group.id,'name':group.name} for group in groups]

def group_revision_list(context, data_dict):
    '''Return a group's revisions.

    :param id: the name or id of the group
    :type id: string

    :rtype: list of dictionaries

    '''
    model = context['model']
    id = _get_or_bust(data_dict, 'id')
    group = model.Group.get(id)
    if group is None:
        raise NotFound

    _check_access('group_revision_list',context, data_dict)

    revision_dicts = []
    for revision, object_revisions in group.all_related_revisions:
        revision_dicts.append(model.revision_as_dict(revision,
                                                     include_packages=False,
                                                     include_groups=False))
    return revision_dicts

def licence_list(context, data_dict):
    '''Return the list of licenses available for datasets on the site.

    :rtype: list of dictionaries

    '''
    model = context["model"]

    _check_access('licence_list',context, data_dict)

    license_register = model.Package.get_license_register()
    licenses = license_register.values()
    licences = [l.as_dict() for l in licenses]
    return licences

def tag_list(context, data_dict):
    '''Return a list of the site's tags.

    By default only free tags (tags that don't belong to a vocabulary) are
    returned. If the ``vocabulary_id`` argument is given then only tags
    belonging to that vocabulary will be returned instead.

    :param query: a tag name query to search for, if given only tags whose
        names contain this string will be returned (optional)
    :type query: string
    :param vocabulary_id: the id or name of a vocabulary, if give only tags
        that belong to this vocabulary will be returned (optional)
    :type vocabulary_id: string
    :param all_fields: return full tag dictionaries instead of just names
        (optional, default: ``False``)
    :type all_fields: boolean

    :rtype: list of dictionaries

    '''
    model = context['model']

    vocab_id_or_name = data_dict.get('vocabulary_id')
    query = data_dict.get('query') or data_dict.get('q')
    if query:
        query = query.strip()
    all_fields = data_dict.get('all_fields', None)

    _check_access('tag_list', context, data_dict)

    if query:
        tags, count = _tag_search(context, data_dict)
    else:
        tags = model.Tag.all(vocab_id_or_name)

    if tags:
        if all_fields:
            tag_list = model_dictize.tag_list_dictize(tags, context)
        else:
            tag_list = [tag.name for tag in tags]
    else:
        tag_list = []

    return tag_list

def user_list(context, data_dict):
    '''Return a list of the site's user accounts.

    :param q: restrict the users returned to those whose names contain a string
      (optional)
    :type q: string
    :param order_by: which field to sort the list by (optional, default:
      ``'name'``)
    :type order_by: string

    :rtype: list of dictionaries

    '''
    model = context['model']
    user = context['user']

    _check_access('user_list',context, data_dict)

    q = data_dict.get('q','')
    order_by = data_dict.get('order_by','name')

    query = model.Session.query(
        model.User,
        model.User.name.label('name'),
        model.User.fullname.label('fullname'),
        model.User.about.label('about'),
        model.User.about.label('email'),
        model.User.created.label('created'),
        _select([_func.count(model.Revision.id)], _or_(
                model.Revision.author==model.User.name,
                model.Revision.author==model.User.openid
                )
        ).label('number_of_edits'),
        _select([_func.count(model.UserObjectRole.id)], _and_(
            model.UserObjectRole.user_id==model.User.id,
            model.UserObjectRole.context=='Package',
            model.UserObjectRole.role=='admin'
            )
        ).label('number_administered_packages')
    )

    if q:
        query = model.User.search(q, query)

    if order_by == 'edits':
        query = query.order_by(_desc(
            _select([_func.count(model.Revision.id)], _or_(
                model.Revision.author==model.User.name,
                model.Revision.author==model.User.openid
                ))
        ))
    else:
        query = query.order_by(
            _case([(_or_(model.User.fullname == None, model.User.fullname == ''),
                   model.User.name)],
                 else_=model.User.fullname)
        )

    ## hack for pagination
    if context.get('return_query'):
        return query

    users_list = []

    for user in query.all():
        result_dict = model_dictize.user_dictize(user[0], context)
        del result_dict['apikey']
        users_list.append(result_dict)

    return users_list

def package_relationships_list(context, data_dict):
    '''Return a dataset (package)'s relationships.

    :param id: the id or name of the package
    :type id: string
    :param id2:
    :type id2:
    :param rel:
    :type rel:

    :rtype: list of dictionaries

    '''
    ##TODO needs to work with dictization layer
    model = context['model']
    user = context['user']
    api = context.get('api_version')

    id = _get_or_bust(data_dict, "id")
    id2 = data_dict.get("id2")
    rel = data_dict.get("rel")
    ref_package_by = 'id' if api == 2 else 'name';
    pkg1 = model.Package.get(id)
    pkg2 = None
    if not pkg1:
        raise NotFound('First package named in request was not found.')
    if id2:
        pkg2 = model.Package.get(id2)
        if not pkg2:
            raise NotFound('Second package named in address was not found.')

    if rel == 'relationships':
        rel = None

    _check_access('package_relationships_list',context, data_dict)

    # TODO: How to handle this object level authz?
    relationships = Authorizer().\
                    authorized_package_relationships(\
                    user, pkg1, pkg2, rel, model.Action.READ)

    if rel and not relationships:
        raise NotFound('Relationship "%s %s %s" not found.'
                                 % (id, rel, id2))

    relationship_dicts = [rel.as_dict(pkg1, ref_package_by=ref_package_by)
                          for rel in relationships]

    return relationship_dicts

def package_show(context, data_dict):
    '''Return the metadata of a dataset (package) and its resources.

    :param id: the id or name of the dataset
    :type id: string

    :rtype: dictionary

    '''
    model = context['model']
    context['session'] = model.Session
    name_or_id = data_dict.get("id") or _get_or_bust(data_dict, 'name_or_id')

    pkg = model.Package.get(name_or_id)

    if pkg is None:
        raise NotFound

    context['package'] = pkg

    _check_access('package_show', context, data_dict)

    package_dict = model_dictize.package_dictize(pkg, context)

    for item in plugins.PluginImplementations(plugins.IPackageController):
        item.read(pkg)

    package_plugin = lib_plugins.lookup_package_plugin(package_dict['type'])
    try:
        schema = package_plugin.db_to_form_schema_options({
            'type':'show',
            'api': 'api_version' in context,
            'context': context })
    except AttributeError:
        schema = package_plugin.db_to_form_schema()

    if schema and context.get('validate', True):
        package_dict, errors = _validate(package_dict, schema, context=context)

    return package_dict

def resource_show(context, data_dict):
    '''Return the metadata of a resource.

    :param id: the id of the resource
    :type id: string

    :rtype: dictionary

    '''
    model = context['model']
    id = _get_or_bust(data_dict, 'id')

    resource = model.Resource.get(id)
    context['resource'] = resource

    if not resource:
        raise NotFound

    _check_access('resource_show', context, data_dict)
    return model_dictize.resource_dictize(resource, context)

def resource_status_show(context, data_dict):
    '''Return the statuses of a resource's tasks.

    :param id: the id of the resource
    :type id: string

    :rtype: list of (status, date_done, traceback, task_status) dictionaries

    '''
    try:
        import ckan.lib.celery_app as celery_app
    except ImportError:
        return {'message': 'queue is not installed on this instance'}

    model = context['model']
    id = _get_or_bust(data_dict, 'id')

    _check_access('resource_status_show', context, data_dict)

    # needs to be text query as celery tables are not in our model
    q = _text("""select status, date_done, traceback, task_status.*
                from task_status left join celery_taskmeta
                on task_status.value = celery_taskmeta.task_id and key = 'celery_task_id'
                where entity_id = :entity_id """)

    result = model.Session.connection().execute(q, entity_id=id)
    result_list = [_table_dictize(row, context) for row in result]

    return result_list

def revision_show(context, data_dict):
    '''Return the details of a revision.

    :param id: the id of the revision
    :type id: string

    :rtype: dictionary

    '''
    model = context['model']
    api = context.get('api_version')
    id = _get_or_bust(data_dict, 'id')
    ref_package_by = 'id' if api == 2 else 'name'

    rev = model.Session.query(model.Revision).get(id)
    if rev is None:
        raise NotFound
    rev_dict = model.revision_as_dict(rev, include_packages=True,
                                      ref_package_by=ref_package_by)
    return rev_dict

def group_show(context, data_dict):
    '''Return the details of a group.

    :param id: the id or name of the group
    :type id: string

    :rtype: dictionary

    '''
    model = context['model']
    id = _get_or_bust(data_dict, 'id')

    group = model.Group.get(id)
    context['group'] = group

    if group is None:
        raise NotFound

    _check_access('group_show',context, data_dict)

    group_dict = model_dictize.group_dictize(group, context)

    for item in plugins.PluginImplementations(plugins.IGroupController):
        item.read(group)

    group_plugin = lib_plugins.lookup_group_plugin(group_dict['type'])
    try:
        schema = group_plugin.db_to_form_schema_options({
            'type':'show',
            'api': 'api_version' in context,
            'context': context })
    except AttributeError:
        schema = group_plugin.db_to_form_schema()

    if schema:
        package_dict, errors = _validate(group_dict, schema, context=context)

    return group_dict

def group_package_show(context, data_dict):
    '''Return the datasets (packages) of a group.

    :param id: the id or name of the group
    :type id: string
    :param limit: the maximum number of datasets to return (optional)
    :type limit: int

    :rtype: list of dictionaries

    '''
    model = context["model"]
    user = context["user"]
    id = _get_or_bust(data_dict, 'id')
    limit = data_dict.get("limit")

    group = model.Group.get(id)
    context['group'] = group
    if group is None:
        raise NotFound

    _check_access('group_show', context, data_dict)

    query = model.Session.query(model.PackageRevision)\
        .filter(model.PackageRevision.state=='active')\
        .filter(model.PackageRevision.current==True)\
        .join(model.Member, model.Member.table_id==model.PackageRevision.id)\
        .join(model.Group, model.Group.id==model.Member.group_id)\
        .filter_by(id=group.id)\
        .order_by(model.PackageRevision.name)

    if limit:
        query = query.limit(limit)

    if context.get('return_query'):
        return query

    result = []
    for pkg_rev in query.all():
        result.append(model_dictize.package_dictize(pkg_rev, context))

    return result

def tag_show(context, data_dict):
    '''Return the details of a tag and all its datasets.

    :param id: the name or id of the tag
    :type id: string

    :returns: the details of the tag, including a list of all of the tag's
        datasets and their details
    :rtype: dictionary

    '''
    model = context['model']
    id = _get_or_bust(data_dict, 'id')

    tag = model.Tag.get(id)
    context['tag'] = tag

    if tag is None:
        raise NotFound

    _check_access('tag_show',context, data_dict)

    tag_dict = model_dictize.tag_dictize(tag,context)

    extended_packages = []
    for package in tag_dict['packages']:
        pkg = model.Package.get(package['id'])
        extended_packages.append(model_dictize.package_dictize(pkg,context))

    tag_dict['packages'] = extended_packages

    return tag_dict

def user_show(context, data_dict):
    '''Return a user account.

    Either the ``id`` or the ``user_obj`` parameter must be given.

    :param id: the id or name of the user (optional)
    :type id: string
    :param user_obj: the user dictionary of the user (optional)
    :type user_obj: user dictionary

    :rtype: dictionary

    '''
    model = context['model']
    user = context['user']

    id = data_dict.get('id',None)
    provided_user = data_dict.get('user_obj',None)
    if id:
        user_obj = model.User.get(id)
        context['user_obj'] = user_obj
        if user_obj is None:
            raise NotFound
    elif provided_user:
        context['user_obj'] = user_obj = provided_user
    else:
        raise NotFound

    _check_access('user_show',context, data_dict)

    user_dict = model_dictize.user_dictize(user_obj,context)

    if not (Authorizer().is_sysadmin(unicode(user)) or user == user_obj.name):
        # If not sysadmin or the same user, strip sensible info
        del user_dict['apikey']
        del user_dict['reset_key']

    revisions_q = model.Session.query(model.Revision
            ).filter_by(author=user_obj.name)

    revisions_list = []
    for revision in revisions_q.limit(20).all():
        revision_dict = revision_show(context,{'id':revision.id})
        revision_dict['state'] = revision.state
        revisions_list.append(revision_dict)
    user_dict['activity'] = revisions_list

    user_dict['datasets'] = []
    dataset_q = model.Session.query(model.Package).join(model.PackageRole
            ).filter_by(user=user_obj, role=model.Role.ADMIN
            ).limit(50)

    for dataset in dataset_q:
        try:
            dataset_dict = package_show(context, {'id': dataset.id})
        except logic.NotAuthorized:
            continue
        user_dict['datasets'].append(dataset_dict)

    return user_dict

def package_show_rest(context, data_dict):
    _check_access('package_show_rest',context, data_dict)

    logic.get_action('package_show')(context, data_dict)

    pkg = context['package']

    package_dict = model_dictize.package_to_api(pkg, context)

    return package_dict

def group_show_rest(context, data_dict):
    _check_access('group_show_rest',context, data_dict)

    logic.get_action('group_show')(context, data_dict)
    group = context['group']

    group_dict = model_dictize.group_to_api(group, context)

    return group_dict

def tag_show_rest(context, data_dict):
    _check_access('tag_show_rest',context, data_dict)

    logic.get_action('tag_show')(context, data_dict)
    tag = context['tag']

    tag_dict = model_dictize.tag_to_api(tag, context)

    return tag_dict

def package_autocomplete(context, data_dict):
    '''Return a list of datasets (packages) that match a string.

    Datasets with names or titles that contain the query string will be
    returned.

    :param q: the string to search for
    :type q: string

    :rtype: list of dictionaries

    '''
    model = context['model']
    session = context['session']
    user = context['user']
    q = _get_or_bust(data_dict, 'q')

    like_q = u"%s%%" % q

    _check_access('package_autocomplete', context, data_dict)

    query = model.Session.query(model.PackageRevision)
    query = query.filter(model.PackageRevision.state=='active')
    query = query.filter(model.PackageRevision.current==True)
    query = query.filter(_or_(model.PackageRevision.name.ilike(like_q),
                                model.PackageRevision.title.ilike(like_q)))
    query = query.limit(10)

    q_lower = q.lower()
    pkg_list = []
    for package in query:
        if package.name.startswith(q_lower):
            match_field = 'name'
            match_displayed = package.name
        else:
            match_field = 'title'
            match_displayed = '%s (%s)' % (package.title, package.name)
        result_dict = {'name':package.name, 'title':package.title,
                       'match_field':match_field, 'match_displayed':match_displayed}
        pkg_list.append(result_dict)

    return pkg_list

def format_autocomplete(context, data_dict):
    '''Return a list of resource formats whose names contain a string.

    :param q: the string to search for
    :type q: string
    :param limit: the maximum number of resource formats to return (optional,
        default: 5)
    :type limit: int

    :rtype: list of strings

    '''
    model = context['model']
    session = context['session']
    user = context['user']

    _check_access('format_autocomplete', context, data_dict)

    q = data_dict.get('q', None)
    if not q:
        return []

    limit = data_dict.get('limit', 5)
    like_q = u'%' + q + u'%'

    query = session.query(model.ResourceRevision.format,
        _func.count(model.ResourceRevision.format).label('total'))\
        .filter(_and_(
            model.ResourceRevision.state == 'active',
            model.ResourceRevision.current == True
        ))\
        .filter(model.ResourceRevision.format.ilike(like_q))\
        .group_by(model.ResourceRevision.format)\
        .order_by('total DESC')\
        .limit(limit)

    return [resource.format.lower() for resource in query]

def user_autocomplete(context, data_dict):
    '''Return a list of user names that contain a string.

    :param q: the string to search for
    :type q: string
    :param limit: the maximum number of user names to return (optional,
        default: 20)
    :type limit: int

    :rtype: a list of user dictionaries each with keys ``'name'``,
        ``'fullname'``, and ``'id'``

    '''
    model = context['model']
    session = context['session']
    user = context['user']
    q = data_dict.get('q',None)
    if not q:
        return []

    _check_access('user_autocomplete', context, data_dict)

    limit = data_dict.get('limit',20)

    query = model.User.search(q).limit(limit)

    user_list = []
    for user in query.all():
        result_dict = {}
        for k in ['id', 'name', 'fullname']:
                result_dict[k] = getattr(user,k)

        user_list.append(result_dict)

    return user_list

def package_search(context, data_dict):
    '''

    :param q:
    :type q:
    :param fields:
    :type fields:
    :param facet_by:
    :type facet_by:
    :param limit:
    :type limit:
    :param offset:
    :type offset:

    :returns:
    :rtype:

    '''
    model = context['model']
    session = context['session']

    _check_access('package_search', context, data_dict)

    # check if some extension needs to modify the search params
    for item in plugins.PluginImplementations(plugins.IPackageController):
        data_dict = item.before_search(data_dict)

    # the extension may have decided that it is not necessary to perform
    # the query
    abort = data_dict.get('abort_search',False)

    results = []
    if not abort:
        # return a list of package ids
        data_dict['fl'] = 'id data_dict'

        query = search.query_for(model.Package)
        query.run(data_dict)

        for package in query.results:
            # get the package object
            package, package_dict = package['id'], package.get('data_dict')
            pkg_query = session.query(model.PackageRevision)\
                .filter(model.PackageRevision.id == package)\
                .filter(_and_(
                    model.PackageRevision.state == u'active',
                    model.PackageRevision.current == True
                ))
            pkg = pkg_query.first()

            ## if the index has got a package that is not in ckan then
            ## ignore it.
            if not pkg:
                log.warning('package %s in index but not in database' % package)
                continue
            ## use data in search index if there
            if package_dict:
                ## the package_dict still needs translating when being viewed
                package_dict = json.loads(package_dict)
                if context.get('for_view'):
                    for item in plugins.PluginImplementations( plugins.IPackageController):
                        package_dict = item.before_view(package_dict)
                results.append(package_dict)
            else:
                results.append(model_dictize.package_dictize(pkg,context))

        count = query.count
        facets = query.facets
    else:
        count = 0
        facets = {}
        results = []

    search_results = {
        'count': count,
        'facets': facets,
        'results': results
    }

    # Transform facets into a more useful data structure.
    restructured_facets = {}
    for key, value in search_results['facets'].items():
        restructured_facets[key] = {
                'title': key,
                'items': []
                }
        for key_, value_ in value.items():
            new_facet_dict = {}
            new_facet_dict['name'] = key_
            if key == 'groups':
                group = model.Group.get(key_)
                if group:
                    new_facet_dict['display_name'] = group.display_name
                else:
                    new_facet_dict['display_name'] = key_
            else:
                new_facet_dict['display_name'] = key_
            new_facet_dict['count'] = value_
            restructured_facets[key]['items'].append(new_facet_dict)
    search_results['search_facets'] = restructured_facets

    # check if some extension needs to modify the search results
    for item in plugins.PluginImplementations(plugins.IPackageController):
        search_results = item.after_search(search_results,data_dict)

    # After extensions have had a chance to modify the facets, sort them by
    # display name.
    for facet in search_results['search_facets']:
        search_results['search_facets'][facet]['items'] = sorted(
                search_results['search_facets'][facet]['items'],
                key=lambda facet: facet['display_name'], reverse=True)

    return search_results

def resource_search(context, data_dict):
    '''

    :param fields:
    :type fields:
    :param order_by:
    :type order_by:
    :param offset:
    :type offset:
    :param limit:
    :type limit:

    :returns:
    :rtype:

    '''
    model = context['model']
    session = context['session']

    fields = _get_or_bust(data_dict, 'fields')
    order_by = data_dict.get('order_by')
    offset = data_dict.get('offset')
    limit = data_dict.get('limit')

    # TODO: should we check for user authentication first?
    q = model.Session.query(model.Resource)
    resource_fields = model.Resource.get_columns()

    for field, terms in fields.items():
        if isinstance(terms, basestring):
            terms = terms.split()
        if field not in resource_fields:
            raise search.SearchError('Field "%s" not recognised in Resource search.' % field)
        for term in terms:
            model_attr = getattr(model.Resource, field)
            if field == 'hash':
                q = q.filter(model_attr.ilike(unicode(term) + '%'))
            elif field in model.Resource.get_extra_columns():
                model_attr = getattr(model.Resource, 'extras')

                like = _or_(
                    model_attr.ilike(u'''%%"%s": "%%%s%%",%%''' % (field, term)),
                    model_attr.ilike(u'''%%"%s": "%%%s%%"}''' % (field, term))
                )
                q = q.filter(like)
            else:
                q = q.filter(model_attr.ilike('%' + unicode(term) + '%'))

    if order_by is not None:
        if hasattr(model.Resource, order_by):
            q = q.order_by(getattr(model.Resource, order_by))

    count = q.count()
    q = q.offset(offset)
    q = q.limit(limit)

    results = []
    for result in q:
        if isinstance(result, tuple) and isinstance(result[0], model.DomainObject):
            # This is the case for order_by rank due to the add_column.
            results.append(result[0])
        else:
            results.append(result)

    return {'count': count, 'results': results}

def _tag_search(context, data_dict):
    model = context['model']

    query = data_dict.get('query') or data_dict.get('q')
    if query:
        query = query.strip()
    terms = [query] if query else []

    fields = data_dict.get('fields', {})
    offset = data_dict.get('offset')
    limit = data_dict.get('limit')

    # TODO: should we check for user authentication first?
    q = model.Session.query(model.Tag)

    if data_dict.has_key('vocabulary_id'):
        # Filter by vocabulary.
        vocab = model.Vocabulary.get(_get_or_bust(data_dict, 'vocabulary_id'))
        if not vocab:
            raise NotFound
        q = q.filter(model.Tag.vocabulary_id == vocab.id)
    else:
        # If no vocabulary_name in data dict then show free tags only.
        q = q.filter(model.Tag.vocabulary_id == None)
        # If we're searching free tags, limit results to tags that are
        # currently applied to a package.
        q = q.distinct().join(model.Tag.package_tags)

    for field, value in fields.items():
        if field in ('tag', 'tags'):
            terms.append(value)

    if not len(terms):
        return [], 0

    for term in terms:
        escaped_term = misc.escape_sql_like_special_characters(term, escape='\\')
        q = q.filter(model.Tag.name.ilike('%' + escaped_term + '%'))

    count = q.count()
    q = q.offset(offset)
    q = q.limit(limit)
    return q.all(), count

def tag_search(context, data_dict):
    '''Return a list of tags whose names contain a given string.

    By default only free tags (tags that don't belong to any vocabulary) are
    searched. If the ``vocabulary_id`` argument is given then only tags
    belonging to that vocabulary will be searched instead.

    :param query: the string to search for
    :type query: string
    :param vocabulary_id: the id or name of the tag vocabulary to search in
      (optional)
    :type vocabulary_id: string
    :param fields:
    :type fields: dictionary
    :param limit: the maximum number of tags to return
    :type limit: int
    :param offset: when ``limit`` is given, the offset to start returning tags
        from
    :type offset: int

    :returns: A dictionary with the following keys:

      ``'count'``
        The number of tags in the result.

      ``'results'``
        The list of tags whose names contain the given string, a list of
        dictionaries.

    :rtype: dictionary

    '''
    tags, count = _tag_search(context, data_dict)
    return {'count': count,
            'results': [_table_dictize(tag, context) for tag in tags]}

def tag_autocomplete(context, data_dict):
    '''Return a list of tag names that contain a given string.

    By default only free tags (tags that don't belong to any vocabulary) are
    searched. If the ``vocabulary_id`` argument is given then only tags
    belonging to that vocabulary will be searched instead.

    :param query: the string to search for
    :type query: string
    :param vocabulary_id: the id or name of the tag vocabulary to search in
      (optional)
    :type vocabulary_id: string
    :param fields:
    :type fields: dictionary
    :param limit: the maximum number of tags to return
    :type limit: int
    :param offset: when ``limit`` is given, the offset to start returning tags
        from
    :type offset: int

    :rtype: list of strings

    '''
    _check_access('tag_autocomplete', context, data_dict)
    matching_tags, count = _tag_search(context, data_dict)
    if matching_tags:
        return [tag.name for tag in matching_tags]
    else:
        return []

def task_status_show(context, data_dict):
    '''Return a task status.

    Either the ``id`` parameter *or* the ``entity_id``, ``task_type`` *and*
    ``key`` parameters must be given.

    :param id: the id of the task status (optional)
    :type id: string
    :param entity_id: the entity_id of the task status (optional)
    :type entity_id: string
    :param task_type: the task_type of the task status (optional)
    :type tast_type: string
    :param key: the key of the task status (optional)
    :type key: string

    :rtype: dictionary

    '''
    model = context['model']
    id = data_dict.get('id')

    if id:
        task_status = model.TaskStatus.get(id)
    else:
        query = model.Session.query(model.TaskStatus)\
            .filter(_and_(
                model.TaskStatus.entity_id == _get_or_bust(data_dict, 'entity_id'),
                model.TaskStatus.task_type == _get_or_bust(data_dict, 'task_type'),
                model.TaskStatus.key == _get_or_bust(data_dict, 'key')
            ))
        task_status = query.first()

    context['task_status'] = task_status

    if task_status is None:
        raise NotFound

    _check_access('task_status_show', context, data_dict)

    task_status_dict = model_dictize.task_status_dictize(task_status, context)
    return task_status_dict

def term_translation_show(context, data_dict):
    '''Return the translations for the given term(s) and language(s).

    :param terms: the terms to search for translations of, e.g. ``'Russian'``,
        ``'romantic novel'``
    :type terms: list of strings
    :param lang_codes: the language codes of the languages to search for
        translations into, e.g. ``'en'``, ``'de'`` (optional, default is to
        search for translations into any language)
    :type lang_codes: list of language code strings

    :rtype: a list of term translation dictionaries each with keys ``'term'``
        (the term searched for, in the source language), ``'term_translation'``
        (the translation of the term into the target language) and
        ``'lang_code'`` (the language code of the target language)

    '''
    model = context['model']

    trans_table = model.term_translation_table

    q = _select([trans_table])

    if 'terms' not in data_dict:
        raise ValidationError({'terms': 'terms not in data'})

    # This action accepts `terms` as either a list of strings, or a single
    # string.
    terms = _get_or_bust(data_dict, 'terms')
    if isinstance(terms, basestring):
        terms = [terms]
    q = q.where(trans_table.c.term.in_(terms))

    # This action accepts `lang_codes` as either a list of strings, or a single
    # string.
    if 'lang_codes' in data_dict:
        lang_codes = _get_or_bust(data_dict, 'lang_codes')
        if isinstance(lang_codes, basestring):
            lang_codes = [lang_codes]
        q = q.where(trans_table.c.lang_code.in_(lang_codes))

    conn = model.Session.connection()
    cursor = conn.execute(q)

    results = []

    for row in cursor:
        results.append(_table_dictize(row, context))

    return results

# Only internal services are allowed to call get_site_user.
def get_site_user(context, data_dict):
    _check_access('get_site_user', context, data_dict)
    model = context['model']
    site_id = config.get('ckan.site_id', 'ckan_site_user')
    user = model.User.get(site_id)
    if not user:
        apikey = str(uuid.uuid4())
        user = model.User(name=site_id,
                          password=apikey,
                          apikey=apikey)
        model.add_user_to_role(user, model.Role.ADMIN, model.System())
        model.Session.add(user)
        model.Session.flush()
        if not context.get('defer_commit'):
            model.Session.commit()
    return {'name': user.name,
            'apikey': user.apikey}

def roles_show(context, data_dict):
    '''Return the roles of all users and authorization groups for an object.

    :param domain_object: a package, group or authorization_group name or id
        to filter the results by
    :type domain_object: string
    :param user: a user name or id
    :type user: string
    :param authorization_group: an authorization group name or id
    :type authorization_group: string

    :rtype: list of dictionaries

    '''
    model = context['model']
    session = context['session']
    domain_object_ref = _get_or_bust(data_dict, 'domain_object')
    user_ref = data_dict.get('user')
    authgroup_ref = data_dict.get('authorization_group')

    domain_object = ckan.logic.action.get_domain_object(model, domain_object_ref)
    if isinstance(domain_object, model.Package):
        query = session.query(model.PackageRole).join('package')
    elif isinstance(domain_object, model.Group):
        query = session.query(model.GroupRole).join('group')
    elif isinstance(domain_object, model.AuthorizationGroup):
        query = session.query(model.AuthorizationGroupRole).join('authorization_group')
    elif domain_object is model.System:
        query = session.query(model.SystemRole)
    else:
        raise NotFound(_('Cannot list entity of this type: %s') % type(domain_object).__name__)
    # Filter by the domain_obj (apart from if it is the system object)
    if not isinstance(domain_object, type):
        query = query.filter_by(id=domain_object.id)

    # Filter by the user / authorized_group
    if user_ref:
        user = model.User.get(user_ref)
        if not user:
            raise NotFound(_('unknown user:') + repr(user_ref))
        query = query.join('user').filter_by(id=user.id)
    if authgroup_ref:
        authgroup = model.AuthorizationGroup.get(authgroup_ref)
        if not authgroup:
            raise NotFound('unknown authorization group:' + repr(authgroup_ref))
        # we need an alias as we join to model.AuthorizationGroup table twice
        ag = _aliased(model.AuthorizationGroup)
        query = query.join(ag, model.AuthorizationGroupRole.authorized_group) \
                .filter_by(id=authgroup.id)

    uors = query.all()

    uors_dictized = [_table_dictize(uor, context) for uor in uors]

    result = {'domain_object_type': type(domain_object).__name__,
              'domain_object_id': domain_object.id if domain_object != model.System else None,
              'roles': uors_dictized}
    if user_ref:
        result['user'] = user.id
    if authgroup_ref:
        result['authorization_group'] = authgroup.id

    return result

def status_show(context, data_dict):
    '''Return a dictionary with information about the site's configuration.'''
    return {
        'site_title': config.get('ckan.site_title'),
        'site_description': config.get('ckan.site_description'),
        'site_url': config.get('ckan.site_url'),
        'ckan_version': ckan.__version__,
        'error_emails_to': config.get('email_to'),
        'locale_default': config.get('ckan.locale_default'),
        'extensions': config.get('ckan.plugins').split(),
        }

def vocabulary_list(context, data_dict):
    '''Return a list of all the site's tag vocabularies.

    :rtype: list of dictionaries

    '''
    model = context['model']
    vocabulary_objects = model.Session.query(model.Vocabulary).all()
    return model_dictize.vocabulary_list_dictize(vocabulary_objects, context)

def vocabulary_show(context, data_dict):
    '''Return a single tag vocabulary.

    :param id: the id or name of the vocabulary
    :type id: string
    :return: the vocabulary.
    :rtype: dictionary

    '''
    model = context['model']
    vocab_id = data_dict.get('id')
    if not vocab_id:
        raise ValidationError({'id': _('id not in data')})
    vocabulary = model.vocabulary.Vocabulary.get(vocab_id)
    if vocabulary is None:
        raise NotFound(_('Could not find vocabulary "%s"') % vocab_id)
    vocabulary_dict = model_dictize.vocabulary_dictize(vocabulary, context)
    return vocabulary_dict

def user_activity_list(context, data_dict):
    '''Return a user's public activity stream.

    :param id: the id or name of the user
    :type id: string

    :rtype: list of dictionaries

    '''
    model = context['model']
    user_id = _get_or_bust(data_dict, 'id')
    query = model.Session.query(model.Activity)
    query = query.filter_by(user_id=user_id)
    query = query.order_by(_desc(model.Activity.timestamp))
    query = query.limit(15)
    activity_objects = query.all()
    return model_dictize.activity_list_dictize(activity_objects, context)

def package_activity_list(context, data_dict):
    '''Return a package's activity stream.

    :param id: the id or name of the package
    :type id: string

    :rtype: list of dictionaries

    '''
    model = context['model']
    package_id = _get_or_bust(data_dict, 'id')
    query = model.Session.query(model.Activity)
    query = query.filter_by(object_id=package_id)
    query = query.order_by(_desc(model.Activity.timestamp))
    query = query.limit(15)
    activity_objects = query.all()
    return model_dictize.activity_list_dictize(activity_objects, context)

def group_activity_list(context, data_dict):
    '''Return a group's activity stream.

    :param id: the id or name of the group
    :type id: string

    :rtype: list of dictionaries

    '''
    model = context['model']
    group_id = _get_or_bust(data_dict, 'id')
    query = model.Session.query(model.Activity)
    query = query.filter_by(object_id=group_id)
    query = query.order_by(_desc(model.Activity.timestamp))
    query = query.limit(15)
    activity_objects = query.all()
    return model_dictize.activity_list_dictize(activity_objects, context)

def recently_changed_packages_activity_list(context, data_dict):
    '''Return the activity stream of all recently added or changed packages.

    :rtype: list of dictionaries

    '''
    model = context['model']
    query = model.Session.query(model.Activity)
    query = query.filter(model.Activity.activity_type.endswith('package'))
    query = query.order_by(_desc(model.Activity.timestamp))
    query = query.limit(15)
    activity_objects = query.all()
    return model_dictize.activity_list_dictize(activity_objects, context)

def activity_detail_list(context, data_dict):
    '''Return an activity's list of activity detail items.

    :param id: the id of the activity
    :type id: string
    :rtype: list of dictionaries.

    '''
    model = context['model']
    activity_id = _get_or_bust(data_dict, 'id')
    activity_detail_objects = model.Session.query(
        model.activity.ActivityDetail).filter_by(activity_id=activity_id).all()
    return model_dictize.activity_detail_list_dictize(activity_detail_objects, context)

def _render_new_package_activity(context, activity):
    return _render('activity_streams/new_package.html',
        extra_vars = {'activity': activity})

def _render_deleted_package_activity(context, activity):
    return _render('activity_streams/deleted_package.html',
        extra_vars = {'activity': activity})

def _render_new_resource_activity(context, activity, detail):
    return _render('activity_streams/new_resource.html',
        extra_vars = {'activity': activity, 'detail': detail})

def _render_changed_resource_activity(context, activity, detail):
    return _render('activity_streams/changed_resource.html',
        extra_vars = {'activity': activity, 'detail': detail})

def _render_deleted_resource_activity(context, activity, detail):
    return _render('activity_streams/deleted_resource.html',
        extra_vars = {'activity': activity, 'detail': detail})

def _render_added_tag_activity(context, activity, detail):
    return _render('activity_streams/added_tag.html',
            extra_vars = {'activity': activity, 'detail': detail})

def _render_removed_tag_activity(context, activity, detail):
    return _render('activity_streams/removed_tag.html',
            extra_vars = {'activity': activity, 'detail': detail})

def _render_new_package_extra_activity(context, activity, detail):
    return _render('activity_streams/new_package_extra.html',
        extra_vars = {'activity': activity, 'detail': detail})

def _render_changed_package_extra_activity(context, activity, detail):
    return _render('activity_streams/changed_package_extra.html',
        extra_vars = {'activity': activity, 'detail': detail})

def _render_deleted_package_extra_activity(context, activity, detail):
    return _render('activity_streams/deleted_package_extra.html',
        extra_vars = {'activity': activity, 'detail': detail})

def _render_changed_package_activity(context, activity):
    details = activity_detail_list(context=context,
        data_dict={'id': activity['id']})

    if len(details) == 1:
        # If an activity has only one activity detail we try to find an
        # activity detail renderer to use instead of rendering the normal
        # 'changed package' template.
        detail = details[0]
        activity_detail_renderers = {
            'Resource': {
              'new': _render_new_resource_activity,
              'changed': _render_changed_resource_activity,
              'deleted': _render_deleted_resource_activity
              },
            'tag': {
              'added': _render_added_tag_activity,
              'removed': _render_removed_tag_activity,
              },
            'PackageExtra': {
                'new': _render_new_package_extra_activity,
                'changed': _render_changed_package_extra_activity,
                'deleted': _render_deleted_package_extra_activity
              },
            }
        object_type = detail['object_type']
        if activity_detail_renderers.has_key(object_type):
            activity_type = detail['activity_type']
            if activity_detail_renderers[object_type].has_key(activity_type):
                renderer = activity_detail_renderers[object_type][activity_type]
                return renderer(context, activity, detail)

    return _render('activity_streams/changed_package.html',
        extra_vars = {'activity': activity})

def _render_new_user_activity(context, activity):
    return _render('activity_streams/new_user.html',
        extra_vars = {'activity': activity})

def _render_changed_user_activity(context, activity):
    return _render('activity_streams/changed_user.html',
        extra_vars = {'activity': activity})

def _render_new_group_activity(context, activity):
    return _render('activity_streams/new_group.html',
        extra_vars = {'activity': activity})

def _render_changed_group_activity(context, activity):
    return _render('activity_streams/changed_group.html',
        extra_vars = {'activity': activity})

def _render_deleted_group_activity(context, activity):
    return _render('activity_streams/deleted_group.html',
        extra_vars = {'activity': activity})

# Global dictionary mapping activity types to functions that render activity
# dicts to HTML snippets for including in HTML pages.
activity_renderers = {
  'new package' : _render_new_package_activity,
  'changed package' : _render_changed_package_activity,
  'deleted package' : _render_deleted_package_activity,
  'new user' : _render_new_user_activity,
  'changed user' : _render_changed_user_activity,
  'new group' : _render_new_group_activity,
  'changed group' : _render_changed_group_activity,
  'deleted group' : _render_deleted_group_activity,
  }

def _activity_list_to_html(context, activity_stream):
    html = []
    for activity in activity_stream:
        activity_type = activity['activity_type']
        if not activity_renderers.has_key(activity_type):
            raise NotImplementedError, ("No activity renderer for activity "
                "type '%s'" % str(activity_type))
        activity_html = activity_renderers[activity_type](context, activity)
        html.append(activity_html)
    return webhelpers.html.literal('\n'.join(html))

def user_activity_list_html(context, data_dict):
    '''Return a user's public activity stream as HTML.

    The activity stream is rendered as a snippet of HTML meant to be included
    in an HTML page, i.e. it doesn't have any HTML header or footer.

    :param id: The id or name of the user.
    :type id: string

    :rtype: string

    '''
    activity_stream = user_activity_list(context, data_dict)
    return _activity_list_to_html(context, activity_stream)

def package_activity_list_html(context, data_dict):
    '''Return a package's activity stream as HTML.

    The activity stream is rendered as a snippet of HTML meant to be included
    in an HTML page, i.e. it doesn't have any HTML header or footer.

    :param id: the id or name of the package
    :type id: string

    :rtype: string

    '''
    activity_stream = package_activity_list(context, data_dict)
    return _activity_list_to_html(context, activity_stream)

def group_activity_list_html(context, data_dict):
    '''Return a group's activity stream as HTML.

    The activity stream is rendered as a snippet of HTML meant to be included
    in an HTML page, i.e. it doesn't have any HTML header or footer.

    :param id: the id or name of the group
    :type id: string

    :rtype: string

    '''
    activity_stream = group_activity_list(context, data_dict)
    return _activity_list_to_html(context, activity_stream)

def recently_changed_packages_activity_list_html(context, data_dict):
    '''Return the activity stream of all recently changed packages as HTML.

    The activity stream includes all recently added or changed packages. It is
    rendered as a snippet of HTML meant to be included in an HTML page, i.e. it
    doesn't have any HTML header or footer.

    :rtype: string

    '''
    activity_stream = recently_changed_packages_activity_list(context,
            data_dict)
    return _activity_list_to_html(context, activity_stream)

def user_follower_count(context, data_dict):
    '''Return the number of followers of a user.

    :param id: the id or name of the user
    :type id: string
    :rtype: int

    '''
    schema = context.get('schema') or (
            ckan.logic.schema.default_follow_user_schema())
    data_dict, errors = _validate(data_dict, schema, context)
    if errors:
        raise ValidationError(errors, ckan.logic.action.error_summary(errors))
    return ckan.model.UserFollowingUser.follower_count(data_dict['id'])

def dataset_follower_count(context, data_dict):
    '''Return the number of followers of a dataset.

    :param id: the id or name of the dataset
    :type id: string
    :rtype: int

    '''
    schema = context.get('schema') or (
            ckan.logic.schema.default_follow_dataset_schema())
    data_dict, errors = _validate(data_dict, schema, context)
    if errors:
        raise ValidationError(errors, ckan.logic.action.error_summary(errors))
    return ckan.model.UserFollowingDataset.follower_count(data_dict['id'])

def _follower_list(context, data_dict, FollowerClass):
    # Get the list of Follower objects.
    model = context['model']
    object_id = data_dict.get('id')
    followers = FollowerClass.follower_list(object_id)

    # Convert the list of Follower objects to a list of User objects.
    users = [model.User.get(follower.follower_id) for follower in followers]
    users = [user for user in users if user is not None]

    # Dictize the list of user objects.
    return [model_dictize.user_dictize(user,context) for user in users]

def user_follower_list(context, data_dict):
    '''Return the list of users that are following the given user.

    :param id: the id or name of the user
    :type id: string
    :rtype: list of dictionaries

    '''
    schema = context.get('schema') or (
            ckan.logic.schema.default_follow_user_schema())
    data_dict, errors = _validate(data_dict, schema, context)
    if errors:
        raise ValidationError(errors, ckan.logic.action.error_summary(errors))
    return _follower_list(context, data_dict,
            context['model'].UserFollowingUser)

def dataset_follower_list(context, data_dict):
    '''Return the list of users that are following the given dataset.

    :param id: the id or name of the dataset
    :type id: string
    :rtype: list of dictionaries

    '''
    schema = context.get('schema') or (
            ckan.logic.schema.default_follow_dataset_schema())
    data_dict, errors = _validate(data_dict, schema, context)
    if errors:
        raise ValidationError(errors, ckan.logic.action.error_summary(errors))
    return _follower_list(context, data_dict,
            context['model'].UserFollowingDataset)

def _am_following(context, data_dict, FollowerClass):
    if not context.has_key('user'):
        raise logic.NotAuthorized

    model = context['model']

    userobj = model.User.get(context['user'])
    if not userobj:
        raise logic.NotAuthorized

    object_id = data_dict.get('id')

    return FollowerClass.is_following(userobj.id, object_id)

def am_following_user(context, data_dict):
    '''Return ``True`` if you're following the given user, ``False`` if not.

    :param id: the id or name of the user
    :type id: string
    :rtype: boolean

    '''
    schema = context.get('schema') or (
            ckan.logic.schema.default_follow_user_schema())
    data_dict, errors = _validate(data_dict, schema, context)
    if errors:
        raise ValidationError(errors, ckan.logic.action.error_summary(errors))

    return _am_following(context, data_dict,
            context['model'].UserFollowingUser)

def am_following_dataset(context, data_dict):
    '''Return ``True`` if you're following the given dataset, ``False`` if not.

    :param id: the id or name of the dataset
    :type id: string
    :rtype: boolean

    '''
    schema = context.get('schema') or (
            ckan.logic.schema.default_follow_dataset_schema())
    data_dict, errors = _validate(data_dict, schema, context)
    if errors:
        raise ValidationError(errors, ckan.logic.action.error_summary(errors))

    return _am_following(context, data_dict,
            context['model'].UserFollowingDataset)