tables.py

# coding: utf-8
from __future__ import unicode_literals

import copy
from collections import OrderedDict
from itertools import count

from django.core.paginator import Paginator
from django.db.models.fields import FieldDoesNotExist
from django.template.loader import get_template
from django.utils import six
from django.utils.functional import cached_property

from . import columns
from .config import RequestConfig
from .rows import BoundRows
from .utils import (AttributeDict, OrderBy, OrderByTuple, Sequence,
                    computed_values, segment)


class TableData(object):
    '''
    Base class for table data containers.
    '''
    def __init__(self, data, table):
        self.data = data
        self.table = table

    def __getitem__(self, key):
        '''
        Slicing returns a new `.TableData` instance, indexing returns a
        single record.
        '''
        return self.data[key]

    def __iter__(self):
        '''
        for ... in ... default to using this. There's a bug in Django 1.3
        with indexing into querysets, so this side-steps that problem (as well
        as just being a better way to iterate).
        '''
        return iter(self.data)

    def get_model(self):
        return getattr(self.data, 'model', None)

    @property
    def ordering(self):
        return None

    @property
    def verbose_name(self):
        return 'item'

    @property
    def verbose_name_plural(self):
        return 'items'

    @staticmethod
    def from_data(data, table):
        if TableQuerysetData.validate(data):
            return TableQuerysetData(data, table)
        elif TableListData.validate(data):
            return TableListData(list(data), table)

        raise ValueError(
            'data must be QuerySet-like (have count() and order_by()) or support'
            ' list(data) -- {} has neither'.format(type(data).__name__)
        )


class TableListData(TableData):
    '''
    Table data container for a list of dicts, for example::

    [
        {'name': 'John', 'age': 20},
        {'name': 'Brian', 'age': 25}
    ]

    .. note::

        Other structures might have worked in the past, but are not explicitly
        supported or tested.
    '''

    @staticmethod
    def validate(data):
        '''
        Validates `data` for use in this container
        '''
        return (
            hasattr(data, '__iter__') or
            (hasattr(data, '__len__') and hasattr(data, '__getitem__'))
        )

    def __len__(self):
        return len(self.data)

    def order_by(self, aliases):
        '''
        Order the data based on order by aliases (prefixed column names) in the
        table.

        Arguments:
            aliases (`~.utils.OrderByTuple`): optionally prefixed names of
                columns ('-' indicates descending order) in order of
                significance with regard to data ordering.
        '''
        accessors = []
        for alias in aliases:
            bound_column = self.table.columns[OrderBy(alias).bare]

            # bound_column.order_by reflects the current ordering applied to
            # the table. As such we need to check the current ordering on the
            # column and use the opposite if it doesn't match the alias prefix.
            if alias[0] != bound_column.order_by_alias[0]:
                accessors += bound_column.order_by.opposite
            else:
                accessors += bound_column.order_by

        self.data.sort(key=OrderByTuple(accessors).key)


class TableQuerysetData(TableData):
    '''
    Table data container for a queryset.
    '''

    @staticmethod
    def validate(data):
        '''
        Validates `data` for use in this container
        '''
        return (
            hasattr(data, 'count') and callable(data.count) and
            hasattr(data, 'order_by') and callable(data.order_by)
        )

    def __len__(self):
        if not hasattr(self, '_length'):
            # Use the queryset count() method to get the length, instead of
            # loading all results into memory. This allows, for example,
            # smart paginators that use len() to perform better.
            self._length = self.data.count()

        return self._length

    @property
    def ordering(self):
        '''
        Returns the list of order by aliases that are enforcing ordering on the
        data.

        If the data is unordered, an empty sequence is returned. If the
        ordering can not be determined, `None` is returned.

        This works by inspecting the actual underlying data. As such it's only
        supported for querysets.
        '''

        aliases = {}
        for bound_column in self.table.columns:
            aliases[bound_column.order_by_alias] = bound_column.order_by
        try:
            return next(segment(self.data.query.order_by, aliases))
        except StopIteration:
            pass

    def order_by(self, aliases):
        '''
        Order the data based on order by aliases (prefixed column names) in the
        table.

        Arguments:
            aliases (`~.utils.OrderByTuple`): optionally prefixed names of
                columns ('-' indicates descending order) in order of
                significance with regard to data ordering.
        '''
        modified_any = False
        accessors = []
        for alias in aliases:
            bound_column = self.table.columns[OrderBy(alias).bare]
            # bound_column.order_by reflects the current ordering applied to
            # the table. As such we need to check the current ordering on the
            # column and use the opposite if it doesn't match the alias prefix.
            if alias[0] != bound_column.order_by_alias[0]:
                accessors += bound_column.order_by.opposite
            else:
                accessors += bound_column.order_by

            if bound_column:
                queryset, modified = bound_column.order(self.data, alias[0] == '-')

                if modified:
                    self.data = queryset
                    modified_any = True

        # custom ordering
        if modified_any:
            return

        # Traditional ordering
        if accessors:
            order_by_accessors = (a.for_queryset() for a in accessors)
            self.data = self.data.order_by(*order_by_accessors)

    @cached_property
    def verbose_name(self):
        '''
        The full (singular) name for the data.

        Model's `~django.db.Model.Meta.verbose_name` is honored.
        '''
        return self.data.model._meta.verbose_name

    @cached_property
    def verbose_name_plural(self):
        '''
        The full (plural) name for the data.

        Model's `~django.db.Model.Meta.verbose_name` is honored.
        '''
        return self.data.model._meta.verbose_name_plural


class DeclarativeColumnsMetaclass(type):
    '''
    Metaclass that converts `.Column` objects defined on a class to the
    dictionary `.Table.base_columns`, taking into account parent class
    `base_columns` as well.
    '''
    def __new__(mcs, name, bases, attrs):
        attrs['_meta'] = opts = TableOptions(attrs.get('Meta', None))

        # extract declared columns
        cols, remainder = [], {}
        for attr_name, attr in attrs.items():
            if isinstance(attr, columns.Column):
                attr._explicit = True
                cols.append((attr_name, attr))
            else:
                remainder[attr_name] = attr
        attrs = remainder

        cols.sort(key=lambda x: x[1].creation_counter)

        # If this class is subclassing other tables, add their fields as
        # well. Note that we loop over the bases in *reverse* - this is
        # necessary to preserve the correct order of columns.
        parent_columns = []
        for base in bases[::-1]:
            if hasattr(base, 'base_columns'):
                parent_columns = list(base.base_columns.items()) + parent_columns

        # Start with the parent columns
        base_columns = OrderedDict(parent_columns)

        # Possibly add some generated columns based on a model
        if opts.model:
            extra = OrderedDict()
            # honor Table.Meta.fields, fallback to model._meta.fields
            if opts.fields is not None:
                # Each item in opts.fields is the name of a model field or a
                # normal attribute on the model
                for field_name in opts.fields:
                    try:
                        field = opts.model._meta.get_field(field_name)
                    except FieldDoesNotExist:
                        extra[field_name] = columns.Column()
                    else:
                        extra[field_name] = columns.library.column_for_field(field)

            else:
                for field in opts.model._meta.fields:
                    extra[field.name] = columns.library.column_for_field(field)

            # update base_columns with extra columns
            for key, col in extra.items():
                # skip current col because the parent was explicitly defined,
                # and the current column is not.
                if key in base_columns and base_columns[key]._explicit is True:
                    continue
                base_columns[key] = col

        # Explicit columns override both parent and generated columns
        base_columns.update(OrderedDict(cols))

        # Apply any explicit exclude setting
        for exclusion in opts.exclude:
            if exclusion in base_columns:
                base_columns.pop(exclusion)

        # Remove any columns from our remainder, else columns from our parent class will remain
        for attr_name in remainder:
            if attr_name in base_columns:
                base_columns.pop(attr_name)

        # Reorder the columns based on explicit sequence
        if opts.sequence:
            opts.sequence.expand(base_columns.keys())
            # Table's sequence defaults to sequence declared in Meta, if the
            # column is not excluded
            base_columns = OrderedDict((
                (x, base_columns[x]) for x in opts.sequence if x in base_columns
            ))

        # Set localize on columns
        for col_name in base_columns.keys():
            localize_column = None
            if col_name in opts.localize:
                localize_column = True
            # unlocalize gets higher precedence
            if col_name in opts.unlocalize:
                localize_column = False

            if localize_column is not None:
                base_columns[col_name].localize = localize_column

        attrs['base_columns'] = base_columns
        return super(DeclarativeColumnsMetaclass, mcs).__new__(mcs, name, bases, attrs)


class TableOptions(object):
    '''
    Extracts and exposes options for a `.Table` from a `.Table.Meta`
    when the table is defined. See `.Table` for documentation on the impact of
    variables in this class.

    Arguments:
        options (`.Table.Meta`): options for a table from `.Table.Meta`
    '''
    def __init__(self, options=None):
        super(TableOptions, self).__init__()
        self.attrs = AttributeDict(getattr(options, 'attrs', {}))
        self.row_attrs = getattr(options, 'row_attrs', {})
        self.default = getattr(options, 'default', '—')
        self.empty_text = getattr(options, 'empty_text', None)
        self.fields = getattr(options, 'fields', None)
        self.exclude = getattr(options, 'exclude', ())
        order_by = getattr(options, 'order_by', None)
        if isinstance(order_by, six.string_types):
            order_by = (order_by, )
        self.order_by = OrderByTuple(order_by) if order_by is not None else None
        self.order_by_field = getattr(options, 'order_by_field', 'sort')
        self.page_field = getattr(options, 'page_field', 'page')
        self.per_page = getattr(options, 'per_page', 25)
        self.per_page_field = getattr(options, 'per_page_field', 'per_page')
        self.prefix = getattr(options, 'prefix', '')
        self.show_header = getattr(options, 'show_header', True)
        self.sequence = Sequence(getattr(options, 'sequence', ()))
        self.orderable = getattr(options, 'orderable', True)
        self.model = getattr(options, 'model', None)
        self.template = getattr(options, 'template', 'django_tables2/table.html')
        self.localize = getattr(options, 'localize', ())
        self.unlocalize = getattr(options, 'unlocalize', ())


class TableBase(object):
    '''
    A representation of a table.

    Arguments:
        data (queryset, list of dicts): The data to display.

        order_by: (tuple or str): The default ordering tuple or comma separated str.
            A hyphen `-` can be used to prefix a column name to indicate
            *descending* order, for example: `('name', '-age')` or `name,-age`.

        orderable (bool): Enable/disable column ordering on this table

        empty_text (str): Empty text to render when the table has no data.
            (default `.Table.Meta.empty_text`)

        exclude (iterable or str): The names of columns that shouldn't be
            included in the table.

        attrs (dict): HTML attributes to add to the ``<table>`` tag.
            When accessing the attribute, the value is always returned as an
            `.AttributeDict` to allow easily conversion to HTML.

        row_attrs: Add custom html attributes to the table rows.
            Allows custom HTML attributes to be specified which will be added
            to the ``<tr>`` tag of the rendered table.

        sequence (iterable): The sequence/order of columns the columns (from
            left to right).

            Items in the sequence must be :term:`column names <column name>`, or
            `'...'` (string containing three periods). `'...'` can be used as a
            catch-all for columns that aren't specified.

        prefix (str): A prefix for querystring fields.
            To avoid name-clashes when  using multiple tables on single page.

        order_by_field (str): If not `None`, defines the name of the *order by*
            querystring field in the url.

        page_field (str): If not `None`, defines the name of the *current page*
            querystring field.

        per_page_field (str): If not `None`, defines the name of the *per page*
            querystring field.

        template (str): The template to render when using ``{% render_table %}``
            (default ``'django_tables2/table.html'``)

        default (str): Text to render in empty cells (determined by
            `.Column.empty_values`, default `.Table.Meta.default`)

        request: Django's request to avoid using `RequestConfig`

        show_header (bool): If `False`, the table will not have a header
            (`<thead>`), defaults to `True`

        show_footer (bool): If `False`, the table footer will not be rendered,
            even if some columns have a footer, defaults to `True`.
    '''
    def __init__(self, data, order_by=None, orderable=None, empty_text=None,
                 exclude=None, attrs=None, row_attrs=None, sequence=None,
                 prefix=None, order_by_field=None, page_field=None,
                 per_page_field=None, template=None, default=None, request=None,
                 show_header=None, show_footer=True):
        super(TableBase, self).__init__()
        self.exclude = exclude or self._meta.exclude
        self.sequence = sequence
        self.data = TableData.from_data(data=data, table=self)
        if default is None:
            default = self._meta.default
        self.default = default
        self.rows = BoundRows(data=self.data, table=self)
        attrs = computed_values(attrs if attrs is not None else self._meta.attrs)
        self.attrs = AttributeDict(attrs)
        self.row_attrs = AttributeDict(row_attrs or self._meta.row_attrs)
        self.empty_text = empty_text if empty_text is not None else self._meta.empty_text
        self.orderable = orderable
        self.prefix = prefix
        self.order_by_field = order_by_field
        self.page_field = page_field
        self.per_page_field = per_page_field
        self.show_header = show_header
        self.show_footer = show_footer

        # Make a copy so that modifying this will not touch the class
        # definition. Note that this is different from forms, where the
        # copy is made available in a ``fields`` attribute.
        self.base_columns = copy.deepcopy(type(self).base_columns)
        # Keep fully expanded ``sequence`` at _sequence so it's easily accessible
        # during render. The priority is as follows:
        # 1. sequence passed in as an argument
        # 2. sequence declared in ``Meta``
        # 3. sequence defaults to '...'
        if sequence is not None:
            self._sequence = Sequence(sequence)
            self._sequence.expand(self.base_columns.keys())
        elif self._meta.sequence:
            self._sequence = self._meta.sequence
        else:
            if self._meta.fields is not None:
                self._sequence = Sequence(tuple(self._meta.fields) + ('...', ))
            else:
                self._sequence = Sequence(('...', ))
            self._sequence.expand(self.base_columns.keys())
        self.columns = columns.BoundColumns(self)
        # `None` value for order_by means no order is specified. This means we
        # `shouldn't touch our data's ordering in any way. *However*
        # `table.order_by = None` means "remove any ordering from the data"
        # (it's equivalent to `table.order_by = ()`).
        if order_by is None and self._meta.order_by is not None:
            order_by = self._meta.order_by
        if order_by is None:
            self._order_by = None
            # If possible inspect the ordering on the data we were given and
            # update the table to reflect that.
            order_by = self.data.ordering
            if order_by is not None:
                self.order_by = order_by
        else:
            self.order_by = order_by
        self.template = template
        # If a request is passed, configure for request
        if request:
            RequestConfig(request).configure(self)

        self._counter = count()

    def as_html(self, request):
        '''
        Render the table to an HTML table, adding `request` to the context.
        '''
        # reset counter for new rendering
        self._counter = count()
        template = get_template(self.template)

        context = {
            'table': self,
            'request': request
        }

        return template.render(context)

    def as_values(self):
        '''
        Return a 2d array of the data which would be shown in the table where the first row is the table headers.

        This can be used to output the table data as CSV, excel, etc
        '''
        headings = [str(c.header) for c in self.columns]
        rows = [[r.get_cell_value(column.name) for column in r.table.columns] for r in self.rows]
        return [headings] + rows

    def has_footer(self):
        '''
        Returns True if any of the columns define a ``_footer`` attribute or a
        ``render_footer()`` method
        '''
        return self.show_footer and any(column.has_footer() for column in self.columns)

    @property
    def show_header(self):
        return (self._show_header if self._show_header is not None
                else self._meta.show_header)

    @show_header.setter
    def show_header(self, value):
        self._show_header = value

    @property
    def order_by(self):
        return self._order_by

    @order_by.setter
    def order_by(self, value):
        '''
        Order the rows of the table based on columns.

        Arguments:
            value: iterable or comma separated string of order by aliases.
        '''
        # collapse empty values to ()
        order_by = () if not value else value
        # accept string
        order_by = order_by.split(',') if isinstance(order_by, six.string_types) else order_by
        valid = []

        # everything's been converted to a iterable, accept iterable!
        for alias in order_by:
            name = OrderBy(alias).bare
            if name in self.columns and self.columns[name].orderable:
                valid.append(alias)
        self._order_by = OrderByTuple(valid)
        self.data.order_by(self._order_by)

    @property
    def order_by_field(self):
        return (self._order_by_field if self._order_by_field is not None
                else self._meta.order_by_field)

    @order_by_field.setter
    def order_by_field(self, value):
        self._order_by_field = value

    @property
    def page_field(self):
        return (self._page_field if self._page_field is not None
                else self._meta.page_field)

    @page_field.setter
    def page_field(self, value):
        self._page_field = value

    def paginate(self, klass=Paginator, per_page=None, page=1, *args, **kwargs):
        '''
        Paginates the table using a paginator and creates a ``page`` property
        containing information for the current page.

        Arguments:
            klass (`~django.core.paginator.Paginator`): A paginator class to
                paginate the results.

            per_page (int): Number of records to display on each page.
            page (int): Page to display.

        Extra arguments are passed to the paginator.

        Pagination exceptions (`~django.core.paginator.EmptyPage` and
        `~django.core.paginator.PageNotAnInteger`) may be raised from this
        method and should be handled by the caller.
        '''

        per_page = per_page or self._meta.per_page
        self.paginator = klass(self.rows, per_page, *args, **kwargs)
        self.page = self.paginator.page(page)

    @property
    def per_page_field(self):
        return (self._per_page_field if self._per_page_field is not None
                else self._meta.per_page_field)

    @per_page_field.setter
    def per_page_field(self, value):
        self._per_page_field = value

    @property
    def prefix(self):
        return (self._prefix if self._prefix is not None
                else self._meta.prefix)

    @prefix.setter
    def prefix(self, value):
        self._prefix = value

    @property
    def prefixed_order_by_field(self):
        return '%s%s' % (self.prefix, self.order_by_field)

    @property
    def prefixed_page_field(self):
        return '%s%s' % (self.prefix, self.page_field)

    @property
    def prefixed_per_page_field(self):
        return '%s%s' % (self.prefix, self.per_page_field)

    @property
    def sequence(self):
        return self._sequence

    @sequence.setter
    def sequence(self, value):
        if value:
            value = Sequence(value)
            value.expand(self.base_columns.keys())
        self._sequence = value

    @property
    def orderable(self):
        if self._orderable is not None:
            return self._orderable
        else:
            return self._meta.orderable

    @orderable.setter
    def orderable(self, value):
        self._orderable = value

    @property
    def template(self):
        if self._template is not None:
            return self._template
        else:
            return self._meta.template

    @template.setter
    def template(self, value):
        self._template = value

    def get_column_class_names(self, classes_set, bound_column):
        '''
        Returns a set of HTML class names for cells (both td and th) of a
        **bound column** in this table.
        By default this returns the column class names defined in the table's
        attributes, and additionally the bound column's name.
        This method can be overridden to change the default behavior, for
        example to simply `return classes_set`.

        Arguments:
            classes_set(set of string): a set of class names to be added
              to the cell, retrieved from the column's attributes. In the case
              of a header cell (th), this also includes ordering classes.
              To set the classes for a column, see `.Column`.
              To configure ordering classes, see :ref:`ordering-class-name`

            bound_column(`.BoundColumn`): the bound column the class names are
              determined for. Useful for accessing `bound_column.name`.

        Returns:
            A set of class names to be added to cells of this column
        '''
        classes_set.add(bound_column.name)
        return classes_set


# Python 2/3 compatible way to enable the metaclass
Table = DeclarativeColumnsMetaclass(str('Table'), (TableBase, ), {})
# ensure the Table class has the right class docstring
Table.__doc__ = TableBase.__doc__