Handle django rest framework HiddenField (#79)

* Added HiddenFieldInspector (#78)
* Updated docs + added test for HiddenField

Added HiddenField to testproj (no change in yaml as expected)

Closes #78.

src/drf_yasg/app_settings.py

@@ -11,6 +11,7 @@ SWAGGER_DEFAULTS = {
         'drf_yasg.inspectors.ChoiceFieldInspector',
         'drf_yasg.inspectors.FileFieldInspector',
         'drf_yasg.inspectors.DictFieldInspector',
+        'drf_yasg.inspectors.HiddenFieldInspector',
         'drf_yasg.inspectors.SimpleFieldInspector',
         'drf_yasg.inspectors.StringDefaultFieldInspector',
     ],

src/drf_yasg/inspectors/__init__.py

@@ -4,7 +4,8 @@ from .base import (
 )
 from .field import (
     CamelCaseJSONFilter, ChoiceFieldInspector, DictFieldInspector, FileFieldInspector, InlineSerializerInspector,
-    ReferencingSerializerInspector, RelatedFieldInspector, SimpleFieldInspector, StringDefaultFieldInspector
+    ReferencingSerializerInspector, RelatedFieldInspector, SimpleFieldInspector, StringDefaultFieldInspector,
+    HiddenFieldInspector,
 )
 from .query import CoreAPICompatInspector, DjangoRestResponsePagination
 from .view import SwaggerAutoSchema
@@ -24,7 +25,7 @@ __all__ = [
     # field inspectors
     'InlineSerializerInspector', 'ReferencingSerializerInspector', 'RelatedFieldInspector', 'SimpleFieldInspector',
     'FileFieldInspector', 'ChoiceFieldInspector', 'DictFieldInspector', 'StringDefaultFieldInspector',
-    'CamelCaseJSONFilter',
+    'CamelCaseJSONFilter', 'HiddenFieldInspector',
 
     # view inspectors
     'SwaggerAutoSchema',

src/drf_yasg/inspectors/field.py

@@ -465,11 +465,21 @@ class DictFieldInspector(FieldInspector):
         return NotHandled
 
 
+class HiddenFieldInspector(FieldInspector):
+    """Hide ``HiddenField``."""
+
+    def field_to_swagger_object(self, field, swagger_object_type, use_references, **kwargs):
+        if isinstance(field, serializers.HiddenField):
+            return None
+
+        return NotHandled
+
+
 class StringDefaultFieldInspector(FieldInspector):
     """For otherwise unhandled fields, return them as plain :data:`.TYPE_STRING` objects."""
 
     def field_to_swagger_object(self, field, swagger_object_type, use_references, **kwargs):  # pragma: no cover
-        # TODO unhandled fields: TimeField HiddenField JSONField
+        # TODO unhandled fields: TimeField JSONField
         SwaggerType, ChildSwaggerType = self._get_partial_types(field, swagger_object_type, use_references, **kwargs)
         return SwaggerType(type=openapi.TYPE_STRING)