xmlmanager.py

# Copyright (c) 2006-2008 Mitch Garnaat http://garnaat.org/
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish, dis-
# tribute, sublicense, and/or sell copies of the Software, and to permit
# persons to whom the Software is furnished to do so, subject to the fol-
# lowing conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.
import boto
from boto.utils import find_class, Password
from boto.sdb.db.key import Key
from boto.sdb.db.model import Model
from datetime import datetime
from xml.dom.minidom import getDOMImplementation, parse, parseString, Node

ISO8601 = '%Y-%m-%dT%H:%M:%SZ'

class XMLConverter:
    """
    Responsible for converting base Python types to format compatible with underlying
    database.  For SimpleDB, that means everything needs to be converted to a string
    when stored in SimpleDB and from a string when retrieved.

    To convert a value, pass it to the encode or decode method.  The encode method
    will take a Python native value and convert to DB format.  The decode method will
    take a DB format value and convert it to Python native format.  To find the appropriate
    method to call, the generic encode/decode methods will look for the type-specific
    method by searching for a method called "encode_<type name>" or "decode_<type name>".
    """
    def __init__(self, manager):
        self.manager = manager
        self.type_map = { bool : (self.encode_bool, self.decode_bool),
                          int : (self.encode_int, self.decode_int),
                          long : (self.encode_long, self.decode_long),
                          Model : (self.encode_reference, self.decode_reference),
                          Key : (self.encode_reference, self.decode_reference),
                          Password : (self.encode_password, self.decode_password),
                          datetime : (self.encode_datetime, self.decode_datetime)}

    def get_text_value(self, parent_node):
        value = ''
        for node in parent_node.childNodes:
            if node.nodeType == node.TEXT_NODE:
                value += node.data
        return value

    def encode(self, item_type, value):
        if item_type in self.type_map:
            encode = self.type_map[item_type][0]
            return encode(value)
        return value

    def decode(self, item_type, value):
        if item_type in self.type_map:
            decode = self.type_map[item_type][1]
            return decode(value)
        else:
            value = self.get_text_value(value)
        return value

    def encode_prop(self, prop, value):
        if isinstance(value, list):
            if hasattr(prop, 'item_type'):
                new_value = []
                for v in value:
                    item_type = getattr(prop, "item_type")
                    if Model in item_type.mro():
                        item_type = Model
                    new_value.append(self.encode(item_type, v))
                return new_value
            else:
                return value
        else:
            return self.encode(prop.data_type, value)

    def decode_prop(self, prop, value):
        if prop.data_type == list:
            if hasattr(prop, 'item_type'):
                item_type = getattr(prop, "item_type")
                if Model in item_type.mro():
                    item_type = Model
                values = []
                for item_node in value.getElementsByTagName('item'):
                    value = self.decode(item_type, item_node)
                    values.append(value)
                return values
            else:
                return self.get_text_value(value)
        else:
            return self.decode(prop.data_type, value)

    def encode_int(self, value):
        value = int(value)
        return '%d' % value

    def decode_int(self, value):
        value = self.get_text_value(value)
        if value:
            value = int(value)
        else:
            value = None
        return value

    def encode_long(self, value):
        value = long(value)
        return '%d' % value

    def decode_long(self, value):
        value = self.get_text_value(value)
        return long(value)

    def encode_bool(self, value):
        if value == True:
            return 'true'
        else:
            return 'false'

    def decode_bool(self, value):
        value = self.get_text_value(value)
        if value.lower() == 'true':
            return True
        else:
            return False

    def encode_datetime(self, value):
        return value.strftime(ISO8601)

    def decode_datetime(self, value):
        value = self.get_text_value(value)
        try:
            return datetime.strptime(value, ISO8601)
        except:
            return None

    def encode_reference(self, value):
        if isinstance(value, str) or isinstance(value, unicode):
            return value
        if value == None:
            return ''
        else:
            val_node = self.manager.doc.createElement("object")
            val_node.setAttribute('id', value.id)
            val_node.setAttribute('class', '%s.%s' % (value.__class__.__module__, value.__class__.__name__))
            return val_node

    def decode_reference(self, value):
        if not value:
            return None
        try:
            value = value.childNodes[0]
            class_name = value.getAttribute("class")
            id = value.getAttribute("id")
            cls = find_class(class_name)
            return cls.get_by_ids(id)
        except:
            return None

    def encode_password(self, value):
        if value and len(value) > 0:
            return str(value)
        else:
            return None

    def decode_password(self, value):
        value = self.get_text_value(value)
        return Password(value)


class XMLManager(object):
    
    def __init__(self, cls, db_name, db_user, db_passwd,
                 db_host, db_port, db_table, ddl_dir, enable_ssl):
        self.cls = cls
        if not db_name:
            db_name = cls.__name__.lower()
        self.db_name = db_name
        self.db_user = db_user
        self.db_passwd = db_passwd
        self.db_host = db_host
        self.db_port = db_port
        self.db_table = db_table
        self.ddl_dir = ddl_dir
        self.s3 = None
        self.converter = XMLConverter(self)
        self.impl = getDOMImplementation()
        self.doc = self.impl.createDocument(None, 'objects', None)

        self.connection = None
        self.enable_ssl = enable_ssl
        self.auth_header = None
        if self.db_user:
            import base64
            base64string = base64.encodebytes('%s:%s' % (self.db_user, self.db_passwd))[:-1]
            authheader =  "Basic %s" % base64string
            self.auth_header = authheader

    def _connect(self):
        if self.db_host:
            if self.enable_ssl:
                from httplib import HTTPSConnection as Connection
            else:
                from httplib import HTTPConnection as Connection

            self.connection = Connection(self.db_host, self.db_port)

    def _make_request(self, method, url, post_data=None, body=None):
        """
        Make a request on this connection
        """
        if not self.connection:
            self._connect()
        try:
            self.connection.close()
        except:
            pass
        self.connection.connect()
        headers = {}
        if self.auth_header:
            headers["Authorization"] = self.auth_header
        self.connection.request(method, url, body, headers)
        resp = self.connection.getresponse()
        return resp

    def new_doc(self):
        return self.impl.createDocument(None, 'objects', None)

    def _object_lister(self, cls, doc):
        for obj_node in doc.getElementsByTagName('object'):
            if not cls:
                class_name = obj_node.getAttribute('class')
                cls = find_class(class_name)
            id = obj_node.getAttribute('id')
            obj = cls(id)
            for prop_node in obj_node.getElementsByTagName('property'):
                prop_name = prop_node.getAttribute('name')
                prop = obj.find_property(prop_name)
                if prop:
                    if hasattr(prop, 'item_type'):
                        value = self.get_list(prop_node, prop.item_type)
                    else:
                        value = self.decode_value(prop, prop_node)
                        value = prop.make_value_from_datastore(value)
                    setattr(obj, prop.name, value)
            yield obj

    def reset(self):
        self._connect()

    def get_doc(self):
        return self.doc
            
    def encode_value(self, prop, value):
        return self.converter.encode_prop(prop, value)

    def decode_value(self, prop, value):
        return self.converter.decode_prop(prop, value)

    def get_s3_connection(self):
        if not self.s3:
            self.s3 = boto.connect_s3(self.aws_access_key_id, self.aws_secret_access_key)
        return self.s3

    def get_list(self, prop_node, item_type):
        values = []
        try:
            items_node = prop_node.getElementsByTagName('items')[0]
        except:
            return []
        for item_node in items_node.getElementsByTagName('item'):
            value = self.converter.decode(item_type, item_node)
            values.append(value)
        return values

    def get_object_from_doc(self, cls, id, doc):
        obj_node = doc.getElementsByTagName('object')[0]
        if not cls:
            class_name = obj_node.getAttribute('class')
            cls = find_class(class_name)
        if not id:
            id = obj_node.getAttribute('id')
        obj = cls(id)
        for prop_node in obj_node.getElementsByTagName('property'):
            prop_name = prop_node.getAttribute('name')
            prop = obj.find_property(prop_name)
            value = self.decode_value(prop, prop_node)
            value = prop.make_value_from_datastore(value)
            if value != None:
                try:
                    setattr(obj, prop.name, value)
                except:
                    pass
        return obj

    def get_props_from_doc(self, cls, id, doc):
        """
        Pull out the properties from this document
        Returns the class, the properties in a hash, and the id if provided as a tuple
        :return: (cls, props, id)
        """
        obj_node = doc.getElementsByTagName('object')[0]
        if not cls:
            class_name = obj_node.getAttribute('class')
            cls = find_class(class_name)
        if not id:
            id = obj_node.getAttribute('id')
        props = {}
        for prop_node in obj_node.getElementsByTagName('property'):
            prop_name = prop_node.getAttribute('name')
            prop = cls.find_property(prop_name)
            value = self.decode_value(prop, prop_node)
            value = prop.make_value_from_datastore(value)
            if value != None:
                props[prop.name] = value
        return (cls, props, id)
        
        
    def get_object(self, cls, id):
        if not self.connection:
            self._connect()

        if not self.connection:
            raise NotImplementedError("Can't query without a database connection")
        url = "/%s/%s" % (self.db_name, id)
        resp = self._make_request('GET', url)
        if resp.status == 200:
            doc = parse(resp)
        else:
            raise Exception("Error: %s" % resp.status)
        return self.get_object_from_doc(cls, id, doc)

    def query(self, cls, filters, limit=None, order_by=None):
        if not self.connection:
            self._connect()

        if not self.connection:
            raise NotImplementedError("Can't query without a database connection")

        from urllib import urlencode

        query = str(self._build_query(cls, filters, limit, order_by))
        if query:
            url = "/%s?%s" % (self.db_name, urlencode({"query": query}))
        else: 
            url = "/%s" % self.db_name
        resp = self._make_request('GET', url)
        if resp.status == 200:
            doc = parse(resp)
        else:
            raise Exception("Error: %s" % resp.status)
        return self._object_lister(cls, doc)

    def _build_query(self, cls, filters, limit, order_by):
        import types
        if len(filters) > 4:
            raise Exception('Too many filters, max is 4')
        parts = []
        properties = cls.properties(hidden=False)
        for filter, value in filters:
            name, op = filter.strip().split()
            found = False
            for property in properties:
                if property.name == name:
                    found = True
                    if types.TypeType(value) == types.ListType:
                        filter_parts = []
                        for val in value:
                            val = self.encode_value(property, val)
                            filter_parts.append("'%s' %s '%s'" % (name, op, val))
                        parts.append("[%s]" % " OR ".join(filter_parts))
                    else:
                        value = self.encode_value(property, value)
                        parts.append("['%s' %s '%s']" % (name, op, value))
            if not found:
                raise Exception('%s is not a valid field' % name)
        if order_by:
            if order_by.startswith("-"):
                key = order_by[1:]
                type = "desc"
            else:
                key = order_by
                type = "asc"
            parts.append("['%s' starts-with ''] sort '%s' %s" % (key, key, type))
        return ' intersection '.join(parts)

    def query_gql(self, query_string, *args, **kwds):
        raise NotImplementedError( "GQL queries not supported in XML" )

    def save_list(self, doc, items, prop_node):
        items_node = doc.createElement('items')
        prop_node.appendChild(items_node)
        for item in items:
            item_node = doc.createElement('item')
            items_node.appendChild(item_node)
            if isinstance(item, Node):
                item_node.appendChild(item)
            else:
                text_node = doc.createTextNode(item)
                item_node.appendChild(text_node)

    def save_object(self, obj, expected_value=None):
        """
        Marshal the object and do a PUT
        """
        doc = self.marshal_object(obj)
        if obj.id:
            url = "/%s/%s" % (self.db_name, obj.id)
        else:
            url = "/%s" % (self.db_name)
        resp = self._make_request("PUT", url, body=doc.toxml())
        new_obj = self.get_object_from_doc(obj.__class__, None, parse(resp))
        obj.id = new_obj.id
        for prop in obj.properties():
            try:
                propname = prop.name
            except AttributeError:
                propname = None
            if propname:
                value = getattr(new_obj, prop.name)
                if value:
                    setattr(obj, prop.name, value)
        return obj


    def marshal_object(self, obj, doc=None):
        if not doc:
            doc = self.new_doc()
        if not doc:
            doc = self.doc
        obj_node = doc.createElement('object')

        if obj.id:
            obj_node.setAttribute('id', obj.id)

        obj_node.setAttribute('class', '%s.%s' % (obj.__class__.__module__,
                                                  obj.__class__.__name__))
        root = doc.documentElement
        root.appendChild(obj_node)
        for property in obj.properties(hidden=False):
            prop_node = doc.createElement('property')
            prop_node.setAttribute('name', property.name)
            prop_node.setAttribute('type', property.type_name)
            value = property.get_value_for_datastore(obj)
            if value is not None:
                value = self.encode_value(property, value)
                if isinstance(value, list):
                    self.save_list(doc, value, prop_node)
                elif isinstance(value, Node):
                    prop_node.appendChild(value)
                else:
                    text_node = doc.createTextNode(unicode(value).encode("ascii", "ignore"))
                    prop_node.appendChild(text_node)
            obj_node.appendChild(prop_node)

        return doc

    def unmarshal_object(self, fp, cls=None, id=None):
        if isinstance(fp, str) or isinstance(fp, unicode):
            doc = parseString(fp)
        else:
            doc = parse(fp)
        return self.get_object_from_doc(cls, id, doc)
    
    def unmarshal_props(self, fp, cls=None, id=None):
        """
        Same as unmarshalling an object, except it returns
        from "get_props_from_doc"
        """
        if isinstance(fp, str) or isinstance(fp, unicode):
            doc = parseString(fp)
        else:
            doc = parse(fp)
        return self.get_props_from_doc(cls, id, doc)

    def delete_object(self, obj):
        url = "/%s/%s" % (self.db_name, obj.id)
        return self._make_request("DELETE", url)

    def set_key_value(self, obj, name, value):
        self.domain.put_attributes(obj.id, {name : value}, replace=True)

    def delete_key_value(self, obj, name):
        self.domain.delete_attributes(obj.id, name)

    def get_key_value(self, obj, name):
        a = self.domain.get_attributes(obj.id, name)
        if a.has_key(name):
            return a[name]
        else:
            return None
    
    def get_raw_item(self, obj):
        return self.domain.get_item(obj.id)

    def set_property(self, prop, obj, name, value):
        pass

    def get_property(self, prop, obj, name):
        pass

    def load_object(self, obj):
        if not obj._loaded:
            obj = obj.get_by_id(obj.id)
            obj._loaded = True
        return obj