web/lib/django/core/management/commands/dumpdata.py
changeset 29 cc9b7e14412b
parent 0 0d40e90630ef
--- a/web/lib/django/core/management/commands/dumpdata.py	Wed May 19 17:43:59 2010 +0200
+++ b/web/lib/django/core/management/commands/dumpdata.py	Tue May 25 02:43:45 2010 +0200
@@ -1,6 +1,7 @@
 from django.core.exceptions import ImproperlyConfigured
 from django.core.management.base import BaseCommand, CommandError
 from django.core import serializers
+from django.db import connections, router, DEFAULT_DB_ALIAS
 from django.utils.datastructures import SortedDict
 
 from optparse import make_option
@@ -11,24 +12,32 @@
             help='Specifies the output serialization format for fixtures.'),
         make_option('--indent', default=None, dest='indent', type='int',
             help='Specifies the indent level to use when pretty-printing output'),
+        make_option('--database', action='store', dest='database',
+            default=DEFAULT_DB_ALIAS, help='Nominates a specific database to load '
+                'fixtures into. Defaults to the "default" database.'),
         make_option('-e', '--exclude', dest='exclude',action='append', default=[],
             help='App to exclude (use multiple --exclude to exclude multiple apps).'),
+        make_option('-n', '--natural', action='store_true', dest='use_natural_keys', default=False,
+            help='Use natural keys if they are available.'),
     )
     help = 'Output the contents of the database as a fixture of the given format.'
-    args = '[appname ...]'
+    args = '[appname appname.ModelName ...]'
 
     def handle(self, *app_labels, **options):
         from django.db.models import get_app, get_apps, get_models, get_model
 
         format = options.get('format','json')
         indent = options.get('indent',None)
+        using = options.get('database', DEFAULT_DB_ALIAS)
+        connection = connections[using]
         exclude = options.get('exclude',[])
         show_traceback = options.get('traceback', False)
+        use_natural_keys = options.get('use_natural_keys', False)
 
-        excluded_apps = [get_app(app_label) for app_label in exclude]
+        excluded_apps = set(get_app(app_label) for app_label in exclude)
 
         if len(app_labels) == 0:
-            app_list = SortedDict([(app, None) for app in get_apps() if app not in excluded_apps])
+            app_list = SortedDict((app, None) for app in get_apps() if app not in excluded_apps)
         else:
             app_list = SortedDict()
             for label in app_labels:
@@ -67,18 +76,91 @@
         except KeyError:
             raise CommandError("Unknown serialization format: %s" % format)
 
+        # Now collate the objects to be serialized.
         objects = []
-        for app, model_list in app_list.items():
-            if model_list is None:
-                model_list = get_models(app)
-
-            for model in model_list:
-                if not model._meta.proxy:
-                    objects.extend(model._default_manager.all())
+        for model in sort_dependencies(app_list.items()):
+            if not model._meta.proxy and router.allow_syncdb(using, model):
+                objects.extend(model._default_manager.using(using).all())
 
         try:
-            return serializers.serialize(format, objects, indent=indent)
+            return serializers.serialize(format, objects, indent=indent,
+                        use_natural_keys=use_natural_keys)
         except Exception, e:
             if show_traceback:
                 raise
             raise CommandError("Unable to serialize database: %s" % e)
+
+def sort_dependencies(app_list):
+    """Sort a list of app,modellist pairs into a single list of models.
+
+    The single list of models is sorted so that any model with a natural key
+    is serialized before a normal model, and any model with a natural key
+    dependency has it's dependencies serialized first.
+    """
+    from django.db.models import get_model, get_models
+    # Process the list of models, and get the list of dependencies
+    model_dependencies = []
+    models = set()
+    for app, model_list in app_list:
+        if model_list is None:
+            model_list = get_models(app)
+
+        for model in model_list:
+            models.add(model)
+            # Add any explicitly defined dependencies
+            if hasattr(model, 'natural_key'):
+                deps = getattr(model.natural_key, 'dependencies', [])
+                if deps:
+                    deps = [get_model(*d.split('.')) for d in deps]
+            else:
+                deps = []
+
+            # Now add a dependency for any FK or M2M relation with
+            # a model that defines a natural key
+            for field in model._meta.fields:
+                if hasattr(field.rel, 'to'):
+                    rel_model = field.rel.to
+                    if hasattr(rel_model, 'natural_key'):
+                        deps.append(rel_model)
+            for field in model._meta.many_to_many:
+                rel_model = field.rel.to
+                if hasattr(rel_model, 'natural_key'):
+                    deps.append(rel_model)
+            model_dependencies.append((model, deps))
+
+    model_dependencies.reverse()
+    # Now sort the models to ensure that dependencies are met. This
+    # is done by repeatedly iterating over the input list of models.
+    # If all the dependencies of a given model are in the final list,
+    # that model is promoted to the end of the final list. This process
+    # continues until the input list is empty, or we do a full iteration
+    # over the input models without promoting a model to the final list.
+    # If we do a full iteration without a promotion, that means there are
+    # circular dependencies in the list.
+    model_list = []
+    while model_dependencies:
+        skipped = []
+        changed = False
+        while model_dependencies:
+            model, deps = model_dependencies.pop()
+
+            # If all of the models in the dependency list are either already
+            # on the final model list, or not on the original serialization list,
+            # then we've found another model with all it's dependencies satisfied.
+            found = True
+            for candidate in ((d not in models or d in model_list) for d in deps):
+                if not candidate:
+                    found = False
+            if found:
+                model_list.append(model)
+                changed = True
+            else:
+                skipped.append((model, deps))
+        if not changed:
+            raise CommandError("Can't resolve dependencies for %s in serialized app list." %
+                ', '.join('%s.%s' % (model._meta.app_label, model._meta.object_name)
+                for model, deps in sorted(skipped, key=lambda obj: obj[0].__name__))
+            )
+        model_dependencies = skipped
+
+    return model_list
\ No newline at end of file