Fixed #3390: the serializer can now contain forward references. Thanks, Russ.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4610 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/management.py

@@ -167,7 +167,8 @@ def _get_sql_model_create(model, known_models=set()):
                 if f.rel.to in known_models:
                     field_output.append(style.SQL_KEYWORD('REFERENCES') + ' ' + \
                         style.SQL_TABLE(backend.quote_name(f.rel.to._meta.db_table)) + ' (' + \
-                        style.SQL_FIELD(backend.quote_name(f.rel.to._meta.get_field(f.rel.field_name).column)) + ')'
+                        style.SQL_FIELD(backend.quote_name(f.rel.to._meta.get_field(f.rel.field_name).column)) + ')' + 
+                        backend.get_deferrable_sql()
                     )
                 else:
                     # We haven't yet created the table to which this field
@@ -210,9 +211,10 @@ def _get_sql_for_pending_references(model, pending_references):
                 # For MySQL, r_name must be unique in the first 64 characters.
                 # So we are careful with character usage here.
                 r_name = '%s_refs_%s_%x' % (r_col, col, abs(hash((r_table, table))))
-                final_output.append(style.SQL_KEYWORD('ALTER TABLE') + ' %s ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s (%s);' % \
+                final_output.append(style.SQL_KEYWORD('ALTER TABLE') + ' %s ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s (%s)%s;' % \
                     (backend.quote_name(r_table), r_name,
-                    backend.quote_name(r_col), backend.quote_name(table), backend.quote_name(col)))
+                    backend.quote_name(r_col), backend.quote_name(table), backend.quote_name(col), 
+                    backend.get_deferrable_sql()))
             del pending_references[model]
     return final_output
 
@@ -232,18 +234,20 @@ def _get_many_to_many_sql_for_model(model):
                 (style.SQL_FIELD(backend.quote_name('id')),
                 style.SQL_COLTYPE(data_types['AutoField']),
                 style.SQL_KEYWORD('NOT NULL PRIMARY KEY')))
-            table_output.append('    %s %s %s %s (%s),' % \
+            table_output.append('    %s %s %s %s (%s)%s,' % \
                 (style.SQL_FIELD(backend.quote_name(f.m2m_column_name())),
                 style.SQL_COLTYPE(data_types[get_rel_data_type(opts.pk)] % opts.pk.__dict__),
                 style.SQL_KEYWORD('NOT NULL REFERENCES'),
                 style.SQL_TABLE(backend.quote_name(opts.db_table)),
-                style.SQL_FIELD(backend.quote_name(opts.pk.column))))
-            table_output.append('    %s %s %s %s (%s),' % \
+                style.SQL_FIELD(backend.quote_name(opts.pk.column)),
+                backend.get_deferrable_sql()))
+            table_output.append('    %s %s %s %s (%s)%s,' % \
                 (style.SQL_FIELD(backend.quote_name(f.m2m_reverse_name())),
                 style.SQL_COLTYPE(data_types[get_rel_data_type(f.rel.to._meta.pk)] % f.rel.to._meta.pk.__dict__),
                 style.SQL_KEYWORD('NOT NULL REFERENCES'),
                 style.SQL_TABLE(backend.quote_name(f.rel.to._meta.db_table)),
-                style.SQL_FIELD(backend.quote_name(f.rel.to._meta.pk.column))))
+                style.SQL_FIELD(backend.quote_name(f.rel.to._meta.pk.column)),
+                backend.get_deferrable_sql()))
             table_output.append('    %s (%s, %s)' % \
                 (style.SQL_KEYWORD('UNIQUE'),
                 style.SQL_FIELD(backend.quote_name(f.m2m_column_name())),

django/core/serializers/python.py

@@ -67,20 +67,19 @@ def Deserializer(object_list, **options):
                 
             field = Model._meta.get_field(field_name)
             
-            # Handle M2M relations (with in_bulk() for performance)
+            # Handle M2M relations
             if field.rel and isinstance(field.rel, models.ManyToManyRel):
                 pks = []
                 for pk in field_value:
                     if isinstance(pk, unicode):
-                        pk = pk.encode(options.get("encoding", settings.DEFAULT_CHARSET))
-                m2m_data[field.name] = field.rel.to._default_manager.in_bulk(field_value).values()
+                        pks.append(pk.encode(options.get("encoding", settings.DEFAULT_CHARSET)))
+                    else:
+                        pks.append(pk)
+                m2m_data[field.name] = pks
                 
             # Handle FK fields
-            elif field.rel and isinstance(field.rel, models.ManyToOneRel) and field_value is not None:
-                try:
-                    data[field.name] = field.rel.to._default_manager.get(pk=field_value)
-                except field.rel.to.DoesNotExist:
-                    data[field.name] = None
+            elif field.rel and isinstance(field.rel, models.ManyToOneRel):
+                data[field.attname] = field_value
                     
             # Handle all other fields
             else:

django/core/serializers/xml_serializer.py

@@ -150,7 +150,7 @@ class Deserializer(base.Deserializer):
             if field.rel and isinstance(field.rel, models.ManyToManyRel):
                 m2m_data[field.name] = self._handle_m2m_field_node(field_node)
             elif field.rel and isinstance(field.rel, models.ManyToOneRel):
-                data[field.name] = self._handle_fk_field_node(field_node)
+                data[field.attname] = self._handle_fk_field_node(field_node)
             else:
                 value = field.to_python(getInnerText(field_node).strip().encode(self.encoding))
                 data[field.name] = value
@@ -162,27 +162,17 @@ class Deserializer(base.Deserializer):
         """
         Handle a <field> node for a ForeignKey
         """
-        # Try to set the foreign key by looking up the foreign related object.
-        # If it doesn't exist, set the field to None (which might trigger 
-        # validation error, but that's expected).
-        RelatedModel = self._get_model_from_node(node, "to")
         # Check if there is a child node named 'None', returning None if so.
         if len(node.childNodes) == 1 and node.childNodes[0].nodeName == 'None':
             return None
         else:
-            return RelatedModel.objects.get(pk=getInnerText(node).strip().encode(self.encoding))
+            return getInnerText(node).strip().encode(self.encoding)
         
     def _handle_m2m_field_node(self, node):
         """
         Handle a <field> node for a ManyToManyField
         """
-        # Load the related model
-        RelatedModel = self._get_model_from_node(node, "to")
-        
-        # Look up all the related objects. Using the in_bulk() lookup ensures
-        # that missing related objects don't cause an exception
-        related_ids = [c.getAttribute("pk").encode(self.encoding) for c in node.getElementsByTagName("object")]
-        return RelatedModel._default_manager.in_bulk(related_ids).values()
+        return [c.getAttribute("pk").encode(self.encoding) for c in node.getElementsByTagName("object")]
     
     def _get_model_from_node(self, node, attr):
         """

django/db/backends/ado_mssql/base.py

@@ -125,6 +125,9 @@ def get_limit_offset_sql(limit, offset=None):
 def get_random_function_sql():
     return "RAND()"
 
+def get_deferrable_sql():
+    return " DEFERRABLE INITIALLY DEFERRED"
+
 def get_fulltext_search_sql(field_name):
     raise NotImplementedError
 

django/db/backends/dummy/base.py

@@ -36,6 +36,7 @@ get_date_extract_sql = complain
 get_date_trunc_sql = complain
 get_limit_offset_sql = complain
 get_random_function_sql = complain
+get_deferrable_sql = complain
 get_fulltext_search_sql = complain
 get_drop_foreignkey_sql = complain
 OPERATOR_MAPPING = {}

django/db/backends/mysql/base.py

@@ -174,6 +174,9 @@ def get_limit_offset_sql(limit, offset=None):
 def get_random_function_sql():
     return "RAND()"
 
+def get_deferrable_sql():
+    return ""
+
 def get_fulltext_search_sql(field_name):
     return 'MATCH (%s) AGAINST (%%s IN BOOLEAN MODE)' % field_name
 

django/db/backends/oracle/base.py

@@ -108,6 +108,9 @@ def get_limit_offset_sql(limit, offset=None):
 def get_random_function_sql():
     return "DBMS_RANDOM.RANDOM"
 
+def get_deferrable_sql():
+    return " DEFERRABLE INITIALLY DEFERRED"
+
 def get_fulltext_search_sql(field_name):
     raise NotImplementedError
 

django/db/backends/postgresql/base.py

@@ -139,6 +139,9 @@ def get_limit_offset_sql(limit, offset=None):
 def get_random_function_sql():
     return "RANDOM()"
 
+def get_deferrable_sql():
+    return " DEFERRABLE INITIALLY DEFERRED"
+    
 def get_fulltext_search_sql(field_name):
     raise NotImplementedError
 

django/db/backends/postgresql_psycopg2/base.py

@@ -99,6 +99,9 @@ def get_limit_offset_sql(limit, offset=None):
 def get_random_function_sql():
     return "RANDOM()"
 
+def get_deferrable_sql():
+    return " DEFERRABLE INITIALLY DEFERRED"
+
 def get_fulltext_search_sql(field_name):
     raise NotImplementedError
 

django/db/backends/sqlite3/base.py

@@ -139,6 +139,9 @@ def get_limit_offset_sql(limit, offset=None):
 def get_random_function_sql():
     return "RANDOM()"
 
+def get_deferrable_sql():
+    return ""
+
 def get_fulltext_search_sql(field_name):
     raise NotImplementedError
 

tests/modeltests/serializers/models.py

@@ -139,4 +139,24 @@ __test__ = {'API_TESTS':"""
 ...     print obj
 <DeserializedObject: Profile of Joe>
 
+# Objects ids can be referenced before they are defined in the serialization data
+# However, the deserialization process will need to be contained within a transaction
+>>> json = '[{"pk": "3", "model": "serializers.article", "fields": {"headline": "Forward references pose no problem", "pub_date": "2006-06-16 15:00:00", "categories": [4, 1], "author": 4}}, {"pk": "4", "model": "serializers.category", "fields": {"name": "Reference"}}, {"pk": "4", "model": "serializers.author", "fields": {"name": "Agnes"}}]'
+>>> from django.db import transaction
+>>> transaction.enter_transaction_management()
+>>> transaction.managed(True)
+>>> for obj in serializers.deserialize("json", json):
+...     obj.save()
+
+>>> transaction.commit()
+>>> transaction.leave_transaction_management()
+
+>>> article = Article.objects.get(pk=3)
+>>> article
+<Article: Forward references pose no problem>
+>>> article.categories.all()
+[<Category: Reference>, <Category: Sports>]
+>>> article.author
+<Author: Agnes>
+
 """}