Fixed #20468 -- Added loaddata --exclude option.

Thanks Alex Morozov for the initial patch.

django/core/management/commands/dumpdata.py

@@ -4,6 +4,7 @@ from collections import OrderedDict
 from django.apps import apps
 from django.core import serializers
 from django.core.management.base import BaseCommand, CommandError
+from django.core.management.utils import parse_apps_and_model_labels
 from django.db import DEFAULT_DB_ALIAS, router
 
 
@@ -81,21 +82,7 @@ class Command(BaseCommand):
         else:
             primary_keys = []
 
-        excluded_apps = set()
-        excluded_models = set()
-        for exclude in excludes:
-            if '.' in exclude:
-                try:
-                    model = apps.get_model(exclude)
-                except LookupError:
-                    raise CommandError('Unknown model in excludes: %s' % exclude)
-                excluded_models.add(model)
-            else:
-                try:
-                    app_config = apps.get_app_config(exclude)
-                except LookupError as e:
-                    raise CommandError(str(e))
-                excluded_apps.add(app_config)
+        excluded_models, excluded_apps = parse_apps_and_model_labels(excludes)
 
         if len(app_labels) == 0:
             if primary_keys:

django/core/management/commands/loaddata.py

@@ -13,6 +13,7 @@ from django.core import serializers
 from django.core.exceptions import ImproperlyConfigured
 from django.core.management.base import BaseCommand, CommandError
 from django.core.management.color import no_style
+from django.core.management.utils import parse_apps_and_model_labels
 from django.db import (
     DEFAULT_DB_ALIAS, DatabaseError, IntegrityError, connections, router,
     transaction,
@@ -52,13 +53,17 @@ class Command(BaseCommand):
             help='Ignores entries in the serialized data for fields that do not '
                  'currently exist on the model.',
         )
+        parser.add_argument(
+            '-e', '--exclude', dest='exclude', action='append', default=[],
+            help='An app_label or app_label.ModelName to exclude. Can be used multiple times.',
+        )
 
     def handle(self, *fixture_labels, **options):
-
         self.ignore = options['ignore']
         self.using = options['database']
         self.app_label = options['app_label']
         self.verbosity = options['verbosity']
+        self.excluded_models, self.excluded_apps = parse_apps_and_model_labels(options['exclude'])
 
         with transaction.atomic(using=self.using):
             self.loaddata(fixture_labels)
@@ -160,6 +165,9 @@ class Command(BaseCommand):
 
                 for obj in objects:
                     objects_in_fixture += 1
+                    if (obj.object._meta.app_config in self.excluded_apps or
+                            type(obj.object) in self.excluded_models):
+                        continue
                     if router.allow_migrate_model(self.using, obj.object.__class__):
                         loaded_objects_in_fixture += 1
                         self.models.add(obj.object.__class__)

django/core/management/utils.py

@@ -4,6 +4,7 @@ import os
 import sys
 from subprocess import PIPE, Popen
 
+from django.apps import apps as installed_apps
 from django.utils import six
 from django.utils.crypto import get_random_string
 from django.utils.encoding import DEFAULT_LOCALE_ENCODING, force_text
@@ -84,3 +85,30 @@ def get_random_secret_key():
     """
     chars = 'abcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*(-_=+)'
     return get_random_string(50, chars)
+
+
+def parse_apps_and_model_labels(labels):
+    """
+    Parse a list of "app_label.ModelName" or "app_label" strings into actual
+    objects and return a two-element tuple:
+        (set of model classes, set of app_configs).
+    Raise a CommandError if some specified models or apps don't exist.
+    """
+    apps = set()
+    models = set()
+
+    for label in labels:
+        if '.' in label:
+            try:
+                model = installed_apps.get_model(label)
+            except LookupError:
+                raise CommandError('Unknown model: %s' % label)
+            models.add(model)
+        else:
+            try:
+                app_config = installed_apps.get_app_config(label)
+            except LookupError as e:
+                raise CommandError(str(e))
+            apps.add(app_config)
+
+    return models, apps

docs/ref/django-admin.txt

@@ -416,6 +416,14 @@ originally generated.
 
 Specifies a single app to look for fixtures in rather than looking in all apps.
 
+.. django-admin-option:: --exclude EXCLUDE, -e EXCLUDE
+
+.. versionadded:: 1.11
+
+Excludes loading the fixtures from the given applications and/or models (in the
+form of ``app_label`` or ``app_label.ModelName``). Use the option multiple
+times to exclude more than one app or model.
+
 What's a "fixture"?
 ~~~~~~~~~~~~~~~~~~~
 

docs/releases/1.11.txt

@@ -169,7 +169,8 @@ Internationalization
 Management Commands
 ~~~~~~~~~~~~~~~~~~~
 
-* ...
+* The new :option:`loaddata --exclude` option allows excluding models and apps
+  while loading data from fixtures.
 
 Migrations
 ~~~~~~~~~~

tests/fixtures/tests.py

@@ -20,7 +20,7 @@ from django.test import (
 from django.utils import six
 from django.utils.encoding import force_text
 
-from .models import Article, ProxySpy, Spy, Tag, Visa
+from .models import Article, Category, ProxySpy, Spy, Tag, Visa
 
 
 class TestCaseFixtureLoadingTests(TestCase):
@@ -370,7 +370,7 @@ class FixtureLoadingTests(DumpDataAssertMixin, TestCase):
             self._dumpdata_assert(['fixtures', 'sites'], '', exclude_list=['foo_app'])
 
         # Excluding a bogus model should throw an error
-        with self.assertRaisesMessage(management.CommandError, "Unknown model in excludes: fixtures.FooModel"):
+        with self.assertRaisesMessage(management.CommandError, "Unknown model: fixtures.FooModel"):
             self._dumpdata_assert(['fixtures', 'sites'], '', exclude_list=['fixtures.FooModel'])
 
     @unittest.skipIf(sys.platform.startswith('win'), "Windows doesn't support '?' in filenames.")
@@ -650,6 +650,30 @@ class FixtureLoadingTests(DumpDataAssertMixin, TestCase):
             format='xml', natural_foreign_keys=True
         )
 
+    def test_loading_with_exclude_app(self):
+        Site.objects.all().delete()
+        management.call_command('loaddata', 'fixture1', exclude=['fixtures'], verbosity=0)
+        self.assertFalse(Article.objects.exists())
+        self.assertFalse(Category.objects.exists())
+        self.assertQuerysetEqual(Site.objects.all(), ['<Site: example.com>'])
+
+    def test_loading_with_exclude_model(self):
+        Site.objects.all().delete()
+        management.call_command('loaddata', 'fixture1', exclude=['fixtures.Article'], verbosity=0)
+        self.assertFalse(Article.objects.exists())
+        self.assertQuerysetEqual(Category.objects.all(), ['<Category: News Stories>'])
+        self.assertQuerysetEqual(Site.objects.all(), ['<Site: example.com>'])
+
+    def test_exclude_option_errors(self):
+        """Excluding a bogus app or model should raise an error."""
+        msg = "No installed app with label 'foo_app'."
+        with self.assertRaisesMessage(management.CommandError, msg):
+            management.call_command('loaddata', 'fixture1', exclude=['foo_app'], verbosity=0)
+
+        msg = "Unknown model: fixtures.FooModel"
+        with self.assertRaisesMessage(management.CommandError, msg):
+            management.call_command('loaddata', 'fixture1', exclude=['fixtures.FooModel'], verbosity=0)
+
 
 class NonExistentFixtureTests(TestCase):
     """