Refactoring filterset creation logic

I have moved it from `DjangoFilterConnectionField` and pushed it
down into `FilterConnectionResolver` where I think it makes
more sense for it to live.

I have also pulled out `get_filtering_args_from_filterset()` as
a utility method.

graphene/contrib/django/fields.py

@@ -1,19 +1,14 @@
 import warnings
 
-import six
-
-from graphene.contrib.django.filterset import setup_filterset
+from graphene.contrib.django.utils import get_filtering_args_from_filterset
+from .resolvers import FilterConnectionResolver
+from .utils import get_type_for_model
 from ...core.exceptions import SkipField
 from ...core.fields import Field
-from ...core.types import Argument, String
 from ...core.types.base import FieldType
 from ...core.types.definitions import List
 from ...relay import ConnectionField
 from ...relay.utils import is_node
-from .form_converter import convert_form_field
-from .resolvers import FilterConnectionResolver
-from .utils import get_type_for_model
-from .filterset import custom_filterset_factory
 
 
 class DjangoConnectionField(ConnectionField):
@@ -69,39 +64,21 @@ class DjangoModelField(FieldType):
 
 class DjangoFilterConnectionField(DjangoConnectionField):
 
-    def __init__(self, type, filterset_class=None, resolver=None, on=None,
-                 fields=None, order_by=None, extra_filter_meta=None,
+    def __init__(self, type, on=None, fields=None, order_by=None,
+                 extra_filter_meta=None, filterset_class=None, resolver=None,
                  *args, **kwargs):
 
-        if not filterset_class:
-            # If no filter class is specified then create one given the
-            # information provided
-            meta = dict(
-                model=type._meta.model,
+        if not resolver:
+            resolver = FilterConnectionResolver(
+                node=type,
+                on=on,
+                filterset_class=filterset_class,
                 fields=fields,
                 order_by=order_by,
+                extra_filter_meta=extra_filter_meta,
             )
-            if extra_filter_meta:
-                meta.update(extra_filter_meta)
-            filterset_class = custom_filterset_factory(**meta)
-        else:
-            filterset_class = setup_filterset(filterset_class)
-
-        if not resolver:
-            resolver = FilterConnectionResolver(type, on, filterset_class)
 
+        filtering_args = get_filtering_args_from_filterset(resolver.get_filterset_class(), type)
         kwargs.setdefault('args', {})
-        kwargs['args'].update(**self.get_filtering_args(type, filterset_class))
+        kwargs['args'].update(**filtering_args)
         super(DjangoFilterConnectionField, self).__init__(type, resolver, *args, **kwargs)
-
-    def get_filtering_args(self, type, filterset_class):
-        args = {}
-        for name, filter_field in six.iteritems(filterset_class.base_filters):
-            field_type = Argument(convert_form_field(filter_field.field))
-            # Is this correct? I don't quite grok the 'parent' system yet
-            field_type.mount(type)
-            args[name] = field_type
-
-        # Also add the 'order_by' field
-        args[filterset_class.order_by_field] = Argument(String)
-        return args

graphene/contrib/django/resolvers.py

@@ -1,5 +1,6 @@
 from django.core.exceptions import ImproperlyConfigured
-from django_filters.filterset import filterset_factory
+
+from graphene.contrib.django.filterset import setup_filterset, custom_filterset_factory
 
 
 class BaseQuerySetConnectionResolver(object):
@@ -50,8 +51,13 @@ class SimpleQuerySetConnectionResolver(BaseQuerySetConnectionResolver):
 class FilterConnectionResolver(BaseQuerySetConnectionResolver):
     # Querying using django-filter
 
-    def __init__(self, node, on=None, filterset_class=None):
+    def __init__(self, node, on=None, filterset_class=None,
+                 fields=None, order_by=None, extra_filter_meta=None):
         self.filterset_class = filterset_class
+        self.fields = fields
+        self.order_by = order_by
+        self.extra_filter_meta = extra_filter_meta or {}
+        self._filterset_class = None
         super(FilterConnectionResolver, self).__init__(node, on)
 
     def make_query(self):
@@ -60,19 +66,40 @@ class FilterConnectionResolver(BaseQuerySetConnectionResolver):
         return filterset.qs
 
     def get_filterset_class(self):
+        """Get the class to be used as the FilterSet"""
+        if self._filterset_class:
+            return self._filterset_class
+
         if self.filterset_class:
-            return self.filterset_class
+            # If were given a FilterSet class, then set it up and
+            # return it
+            self._filterset_class = setup_filterset(self.filterset_class)
         elif self.model:
-            return filterset_factory(self.model)
+            # If no filter class was specified then create one given the
+            # other information provided
+            meta = dict(
+                model=self.model,
+                fields=self.fields,
+                order_by=self.order_by,
+            )
+            meta.update(self.extra_filter_meta)
+            self._filterset_class = custom_filterset_factory(**meta)
         else:
-            msg = "'%s' must define 'filterset_class' or 'model'"
+            msg = "Neither 'filterset_class' or 'model' available in '%s'. " \
+                  "Either pass in 'filterset_class' or 'model' when " \
+                  "initialising, or extend this class and override " \
+                  "get_filterset() or get_filterset_class()"
             raise ImproperlyConfigured(msg % self.__class__.__name__)
 
+        return self._filterset_class
+
     def get_filterset(self, filterset_class):
+        """Get an instance of the FilterSet"""
         kwargs = self.get_filterset_kwargs(filterset_class)
         return filterset_class(**kwargs)
 
     def get_filterset_kwargs(self, filterset_class):
+        """Get the kwargs to use when initialising the FilterSet class"""
         kwargs = {
             'data': self.args or None,
             'queryset': self.get_manager()

graphene/contrib/django/tests/test_fields.py

@@ -98,7 +98,7 @@ def test_filter_shortcut_filterset_extra_meta():
 
 def test_global_id_field_implicit():
     field = DjangoFilterConnectionField(ArticleNode, fields=['id'])
-    filterset_class = field.resolver_fn.filterset_class
+    filterset_class = field.resolver_fn.get_filterset_class()
     id_filter = filterset_class.base_filters['id']
     assert isinstance(id_filter, GlobalIDFilter)
     assert id_filter.field_class == GlobalIDFormField
@@ -111,7 +111,7 @@ def test_global_id_field_explicit():
             fields = ['id']
 
     field = DjangoFilterConnectionField(ArticleNode, filterset_class=ArticleIdFilter)
-    filterset_class = field.resolver_fn.filterset_class
+    filterset_class = field.resolver_fn.get_filterset_class()
     id_filter = filterset_class.base_filters['id']
     assert isinstance(id_filter, GlobalIDFilter)
     assert id_filter.field_class == GlobalIDFormField
@@ -119,7 +119,7 @@ def test_global_id_field_explicit():
 
 def test_global_id_field_relation():
     field = DjangoFilterConnectionField(ArticleNode, fields=['reporter'])
-    filterset_class = field.resolver_fn.filterset_class
+    filterset_class = field.resolver_fn.get_filterset_class()
     id_filter = filterset_class.base_filters['reporter']
     assert isinstance(id_filter, GlobalIDFilter)
     assert id_filter.field_class == GlobalIDFormField

graphene/contrib/django/tests/test_resolvers.py

@@ -66,7 +66,7 @@ def test_filter_get_filterset_class_explicit():
     resolver = FilterConnectionResolver(ReporterNode,
                                         filterset_class=ReporterFilter)
     resolver(inst=reporter, args={}, info=None)
-    assert resolver.get_filterset_class() == ReporterFilter, \
+    assert issubclass(resolver.get_filterset_class(), ReporterFilter), \
         'ReporterFilter not returned'
 
 
@@ -83,7 +83,7 @@ def test_filter_get_filterset_class_error():
     resolver.model = None
     with raises(ImproperlyConfigured) as excinfo:
         resolver(inst=reporter, args={}, info=None)
-    assert "must define 'filterset_class' or 'model'" in str(excinfo.value)
+    assert "Neither 'filterset_class' or 'model' available" in str(excinfo.value)
 
 
 def test_filter_filter():

graphene/contrib/django/utils.py

@@ -1,6 +1,10 @@
+import six
 from django.db import models
 from django.db.models.manager import Manager
 
+from graphene import Argument, String
+from graphene.contrib.django.form_converter import convert_form_field
+
 
 def get_type_for_model(schema, model):
     schema = schema
@@ -23,3 +27,20 @@ def maybe_queryset(value):
     if isinstance(value, Manager):
         value = value.get_queryset()
     return value
+
+
+def get_filtering_args_from_filterset(filterset_class, type):
+    """ Inspect a FilterSet and produce the arguments to pass to
+        a Graphene Field. These arguments will be available to
+        filter against in the GraphQL
+    """
+    args = {}
+    for name, filter_field in six.iteritems(filterset_class.base_filters):
+        field_type = Argument(convert_form_field(filter_field.field))
+        # Is this correct? I don't quite grok the 'parent' system yet
+        field_type.mount(type)
+        args[name] = field_type
+
+    # Also add the 'order_by' field
+    args[filterset_class.order_by_field] = Argument(String)
+    return args