Dependency sorting

django_seed/guessers.py

@@ -101,9 +101,9 @@ def guess_format(self, field):
             return lambda x: provider.comma_sep_ints()
 
         if isinstance(field, BinaryField): return lambda x: provider.binary()
-        if isinstance(field, ImageField): return lambda x: None
+        if isinstance(field, ImageField): return lambda x: provider.file_name()
         if isinstance(field, FilePathField): return lambda x: provider.file_name()
-        if isinstance(field, FileField): return lambda x: None
+        if isinstance(field, FileField): return lambda x: provider.file_name()
 
         if isinstance(field, CharField):
             if field.choices:

django_seed/management/commands/seed.py

@@ -1,7 +1,9 @@
 
 from django.core.management.base import AppCommand
+from django.db.models import ForeignKey
 from django_seed import Seed
 from django_seed.exceptions import SeederCommandError
+from django_seed.toposort import toposort_flatten
 from optparse import make_option
 import django
 
@@ -11,10 +13,10 @@ class Command(AppCommand):
 
     args = "[appname ...]"
 
-    option_list = AppCommand.option_list + (
+    option_list = [
         make_option('--number', dest='number', default=10,
                     help='number of each model to seed'),
-    )
+    ]
 
     def handle_app_config(self, app_config, **options):
         if app_config.models_module is None:
@@ -27,10 +29,31 @@ def handle_app_config(self, app_config, **options):
 
         seeder = Seed.seeder()
 
-        for model in app_config.get_models():
+        for model in self.sorted_models(app_config):
             seeder.add_entity(model, number)
             print('Seeding %i %ss' % (number, model.__name__))
 
         pks = seeder.execute()
         print(pks)
 
+    def dependencies(self, model):
+        dependencies = set()
+        if hasattr(model._meta, 'get_fields'):  # Django>=1.8
+            for field in model._meta.get_fields():
+                if field.many_to_one is True and field.concrete and field.blank is False:
+                    dependencies.add(field.related_model)
+        else:  # Django<=1.7
+            for field in model._meta.fields:
+                if isinstance(field, ForeignKey) and field.blank is False:
+                    dependencies.add(field.rel.to)
+        return dependencies
+
+    def sorted_models(self, app_config):
+        dependencies = {}
+        for model in app_config.get_models():
+            dependencies[model] = self.dependencies(model)
+        try:
+            return toposort_flatten(dependencies)
+        except ValueError as ex:
+            raise SeederCommandError(str(ex))
+

django_seed/providers.py

@@ -7,7 +7,7 @@
 import sys
 
 
-file_extenstions = ( "flac", "mp3", "wav", "bmp", "gif", "jpeg", "jpg", "png",
+file_extensions = ( "flac", "mp3", "wav", "bmp", "gif", "jpeg", "jpg", "png",
                      "tiff", "css", "csv", "html", "js", "json", "txt", "mp4",
                      "avi", "mov", "webm" )
 
@@ -45,7 +45,7 @@ def rand_float(self):
 
     def file_name(self):
         filename = self.faker.word()
-        extension = random.choice(file_extenstions)
+        extension = random.choice(file_extensions)
         return '{0}.{1}'.format(filename, extension)
 
     def comma_sep_ints(self):

django_seed/toposort.py

@@ -0,0 +1,72 @@
+#######################################################################
+# Implements a topological sort algorithm.
+# https://bitbucket.org/ericvsmith/toposort/src/25b5894c4229cb888f77cf0c077c05e2464446ac/toposort.py
+#
+# Copyright 2014 True Blade Systems, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+########################################################################
+
+from functools import reduce as _reduce
+
+
+__all__ = ['toposort', 'toposort_flatten']
+
+
+def toposort(data):
+    """Dependencies are expressed as a dictionary whose keys are items
+and whose values are a set of dependent items. Output is a list of
+sets in topological order. The first set consists of items with no
+dependences, each subsequent set consists of items that depend upon
+items in the preceeding sets.
+"""
+
+    # Special case empty input.
+    if len(data) == 0:
+        return
+
+    # Copy the input so as to leave it unmodified.
+    data = data.copy()
+
+    # Ignore self dependencies.
+    for k, v in data.items():
+        v.discard(k)
+    # Find all items that don't depend on anything.
+    extra_items_in_deps = _reduce(set.union, data.values()) - set(data.keys())
+    # Add empty dependences where needed.
+    data.update({item:set() for item in extra_items_in_deps})
+    while True:
+        ordered = set(item for item, dep in data.items() if len(dep) == 0)
+        if not ordered:
+            break
+        yield ordered
+        data = {item: (dep - ordered)
+                for item, dep in data.items()
+                    if item not in ordered}
+    if len(data) != 0:
+        raise ValueError('Cyclic dependencies exist among these items: {}'.format(', '.join(repr(x) for x in data.items())))
+
+
+def toposort_flatten(data, sort=True):
+    """Returns a single list of dependencies. For any set returned by
+toposort(), those items are sorted and appended to the result (just to
+make the results deterministic)."""
+
+    result = []
+    for d in toposort(data):
+        try:
+            result.extend((sorted if sort else list)(d))
+        except TypeError as e:
+            result.extend(list(d))
+    return result