Show warning on ref_name collisions

Closes #156

src/drf_yasg/generators.py

@@ -31,8 +31,7 @@ class EndpointEnumerator(_EndpointEnumerator):
 
     def get_path_from_regex(self, path_regex):
         if path_regex.endswith(')'):
-            logger.warning("url pattern does not end in $ ('%s') - unexpected things might happen",
+            logger.warning("url pattern does not end in $ ('%s') - unexpected things might happen", path_regex)
-                           path_regex)
         return self.unescape_path(super(EndpointEnumerator, self).get_path_from_regex(path_regex))
 
     def should_include_endpoint(self, path, callback, app_name='', namespace='', url_name=None):

src/drf_yasg/inspectors/field.py

@@ -13,7 +13,7 @@ from rest_framework.settings import api_settings as rest_framework_settings
 
 from .. import openapi
 from ..errors import SwaggerGenerationError
-from ..utils import decimal_as_float, filter_none, get_serializer_ref_name
+from ..utils import decimal_as_float, filter_none, get_serializer_ref_name, get_serializer_class
 from .base import FieldInspector, NotHandled, SerializerInspector
 
 try:
@@ -107,7 +107,7 @@ class InlineSerializerInspector(SerializerInspector):
                 )
                 if not ref_name and 'title' in result:
                     # on an inline model, the title is derived from the field name
-                    # but is visually displayed like the model name, which is confusing
+                    # but is visno coverually displayed like the model name, which is confusing
                     # it is better to just remove title from inline models
                     del result.title
 
@@ -117,7 +117,13 @@ class InlineSerializerInspector(SerializerInspector):
                 return make_schema_definition()
 
             definitions = self.components.with_scope(openapi.SCHEMA_DEFINITIONS)
-            definitions.setdefault(ref_name, make_schema_definition)
+            actual_schema = definitions.setdefault(ref_name, make_schema_definition)
+            actual_serializer = get_serializer_class(getattr(actual_schema, '_serializer', None))
+            this_serializer = get_serializer_class(field)
+            if actual_serializer and actual_serializer != this_serializer:  # pragma: no cover
+                logger.warning("Schema for %s will override distinct serializer %s because they "
+                               "share the same ref_name", actual_serializer, this_serializer)
+
             return openapi.SchemaRef(definitions, ref_name)
 
         return NotHandled

src/drf_yasg/openapi.py

@@ -1,3 +1,4 @@
+import logging
 import re
 from collections import OrderedDict
 
@@ -7,6 +8,8 @@ from inflection import camelize
 
 from .utils import filter_none
 
+logger = logging.getLogger(__name__)
+
 TYPE_OBJECT = "object"  #:
 TYPE_STRING = "string"  #:
 TYPE_NUMBER = "number"  #:
@@ -628,8 +631,13 @@ class ReferenceResolver(object):
         ret = self.getdefault(name, None, scope)
         if ret is None:
             ret = maker()
+            value = self.getdefault(name, None, scope)
             assert ret is not None, "maker returned None; referenced objects cannot be None/null"
-            self.set(name, ret, scope)
+            if value is None:
+                self.set(name, ret, scope)
+            elif value != ret:
+                logger.debug("during setdefault, maker for %s inserted a value and returned a different value", name)
+                ret = value
 
         return ret
 

src/drf_yasg/utils.py

@@ -274,6 +274,7 @@ def force_serializer_instance(serializer):
 
     :param serializer: serializer class or instance
     :return: serializer instance
+    :rtype: serializers.BaseSerializer
     """
     if inspect.isclass(serializer):
         assert issubclass(serializer, serializers.BaseSerializer), "Serializer required, not %s" % serializer.__name__
@@ -284,6 +285,26 @@ def force_serializer_instance(serializer):
     return serializer
 
 
+def get_serializer_class(serializer):
+    """Given a ``Serializer`` class or intance, return the ``Serializer`` class. If `serializer` is not a ``Serializer``
+    class or instance, raises an assertion error.
+
+    :param serializer: serializer class or instance, or ``None``
+    :return: serializer class
+    :rtype: type[serializers.BaseSerializer]
+    """
+    if serializer is None:
+        return None
+
+    if inspect.isclass(serializer):
+        assert issubclass(serializer, serializers.BaseSerializer), "Serializer required, not %s" % serializer.__name__
+        return serializer
+
+    assert isinstance(serializer, serializers.BaseSerializer), \
+        "Serializer class or instance required, not %s" % type(serializer).__name__
+    return type(serializer)
+
+
 def get_consumes(parser_classes):
     """Extract ``consumes`` MIME types from a list of parser classes.
 
@@ -336,7 +357,7 @@ def get_serializer_ref_name(serializer):
     if hasattr(serializer_meta, 'ref_name'):
         ref_name = serializer_meta.ref_name
     elif serializer_name == 'NestedSerializer' and isinstance(serializer, serializers.ModelSerializer):
-        logger.debug("Forcing inline output for ModelSerializer named 'NestedSerializer': " + str(serializer))
+        logger.debug("Forcing inline output for ModelSerializer named 'NestedSerializer':\n" + str(serializer))
         ref_name = None
     else:
         ref_name = serializer_name