Replace SnippetObjectType with SnippetInterface

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## Unreleased
 
+### Changed
+
+-   `SnippetObjectType` is replaced with `SnippetInterface` ([405](https://github.com/torchbox/wagtail-grapple/pull/405)) @mgax
+
 ### Fixed
 
 -   `value` not being queryable on `EmbedBlock` ([#399](https://github.com/torchbox/wagtail-grapple/pull/399))@JakubMastalerz

docs/general-usage/decorators.rst

@@ -433,12 +433,12 @@ To register additional interfaces for the block, add them with your block's ``gr
     from grapple.helpers import register_streamfield_block
 
 
-    class CustomInterface(graphene.Interface):
+    class MyInterface(graphene.Interface):
         text = graphene.String()
 
 
     @register_streamfield_block
-    class CustomInterfaceBlock(blocks.StructBlock):
+    class MyInterfaceBlock(blocks.StructBlock):
         text = blocks.TextBlock()
 
-        graphql_interfaces = (CustomInterface,)
+        graphql_interfaces = (MyInterface,)

docs/general-usage/graphql-types.rst

@@ -102,33 +102,6 @@ The following fields are returned:
     fileHash: String
 
 
-
-SnippetObjectType
-^^^^^^^^^^^^^^^^^
-
-You won't see much of ``SnippetObjectType`` as it's only a Union type that
-groups all your Snippet models together. You can query all the available snippets
-under the ``snippets`` field under the root Query, The query is similar to
-an interface but ``SnippetObjectType`` doesn't provide any fields itself.
-
-When snippets are attached to Pages you interact with your generated type itself
-as opposed to an interface or base type.
-
-An example of querying all snippets:
-
-::
-
-    query {
-        snippets {
-            ...on Advert {
-                id
-                url
-                text
-            }
-        }
-    }
-
-
 SettingObjectType
 ^^^^^^^^^^^^^^^^^
 

docs/general-usage/interfaces.rst

@@ -50,7 +50,7 @@ the name of the model:
     }
 
 You can change the default ``PageInterface`` to your own interface by changing the
-:ref:`PAGE_INTERFACE<page interface settings>` setting.
+:ref:`PAGE_INTERFACE<page interface setting>` setting.
 
 As mentioned above there is both a plural ``pages`` and singular ``page``
 field on the root Query type that returns a ``PageInterface``.
@@ -107,6 +107,37 @@ in the interface:
 
 
 
+``SnippetInterface``
+--------------------
+
+``SnippetInterface`` is the default interface for all Wagtail snippet models. It is accessible through the
+``snippets`` field on the root query type. It exposes the following fields:
+
+::
+
+    snippetType: String!
+    contentType: String!
+
+An example of querying all snippets:
+
+::
+
+    query {
+        snippets {
+            snippetType
+            contentType
+            ...on Advert {
+                id
+                url
+                text
+            }
+        }
+    }
+
+You can change the default ``SnippetInterface`` to your own interface by changing the
+:ref:`SNIPPET_INTERFACE<snippet interface setting>` setting.
+
+
 Adding your own interfaces
 --------------------------
 
@@ -118,49 +149,48 @@ Given the following example interface:
 .. code-block:: python
 
     # interfaces.py
-    from .interfaces import CustomInterface
-
-
-    class CustomInterface(graphene.Interface):
+    class MyInterface(graphene.Interface):
         custom_field = graphene.String()
 
 you could add it to your Page model like so:
 
 .. code-block:: python
 
     from wagtail.models import Page
+    from .interfaces import MyInterface
 
 
     class MyPage(Page):
         # ...
 
-        graphql_interfaces = (CustomInterface,)
+        graphql_interfaces = (MyInterface,)
 
 or any Django model:
 
 .. code-block:: python
 
     # models.py
     from django.db import models
+    from .interfaces import MyInterface
 
 
     class MyModel(models.Model):
         # ...
 
-        graphql_interfaces = (CustomInterface,)
-
+        graphql_interfaces = (MyInterface,)
 
 or a ``StreamField`` block:
 
 .. code-block:: python
 
     # blocks.py
     from wagtail.core import blocks
+    from .interfaces import MyInterface
 
 
     class MyStructBlock(blocks.StructBlock):
         # ...
 
-        graphql_interfaces = (CustomInterface,)
+        graphql_interfaces = (MyInterface,)
 
 The provided interfaces will be added to the base interfaces for the model.

docs/getting-started/settings.rst

@@ -141,10 +141,10 @@ Limit the maximum number of items that ``QuerySetList`` and ``PaginatedQuerySet`
 Default: ``100``
 
 
-.. _page interface settings:
+Wagtail model interfaces
+^^^^^^^^^^^^^^^^^^^^^^^^
 
-Wagtail Page interface
-^^^^^^^^^^^^^^^^^^^^^^
+.. _page interface setting:
 
 ``PAGE_INTERFACE``
 ******************
@@ -153,3 +153,14 @@ Used to construct the schema for Wagtail Page-derived models. It can be overridd
 page models.
 
 Default: ``grapple.types.interfaces.PageInterface``
+
+
+.. _snippet interface setting:
+
+``SNIPPET_INTERFACE``
+*********************
+
+Used to construct the schema for Wagtail snippet models. It can be overridden to provide a custom interface for all
+snippet models.
+
+Default: ``grapple.types.interfaces.SnippetInterface``

grapple/actions.py

@@ -27,6 +27,7 @@
 from .types.images import ImageObjectType, ImageRenditionObjectType
 from .types.pages import Page, get_page_interface
 from .types.rich_text import RichText as RichTextType
+from .types.snippets import get_snippet_interface
 from .types.streamfield import generate_streamfield_union
 
 
@@ -612,7 +613,7 @@ def register_snippet_model(cls: Type[models.Model], type_prefix: str):
         return
 
     # Create a GQL type that implements Snippet Interface
-    snippet_node_type = build_node_type(cls, type_prefix, None)
+    snippet_node_type = build_node_type(cls, type_prefix, get_snippet_interface())
 
     if snippet_node_type:
         registry.snippets[cls] = snippet_node_type

grapple/settings.py

@@ -29,6 +29,7 @@
     "MAX_PAGE_SIZE": 100,
     "RICHTEXT_FORMAT": "html",
     "PAGE_INTERFACE": "grapple.types.interfaces.PageInterface",
+    "SNIPPET_INTERFACE": "grapple.types.interfaces.SnippetInterface",
 }
 
 # List of settings that have been deprecated

grapple/types/interfaces.py

@@ -209,3 +209,25 @@ def resolve_raw_value(self, info, **kwargs):
             return self.value.source
 
         return self.value
+
+
+def get_snippet_interface():
+    return import_string(grapple_settings.SNIPPET_INTERFACE)
+
+
+class SnippetInterface(graphene.Interface):
+    snippet_type = graphene.String(required=True)
+    content_type = graphene.String(required=True)
+
+    @classmethod
+    def resolve_type(cls, instance, info, **kwargs):
+        return registry.snippets[type(instance)]
+
+    def resolve_snippet_type(self, info, **kwargs):
+        return self.__class__.__name__
+
+    def resolve_content_type(self, info, **kwargs):
+        self.content_type = ContentType.objects.get_for_model(self)
+        return (
+            f"{self.content_type.app_label}.{self.content_type.model_class().__name__}"
+        )

grapple/types/snippets.py

@@ -1,49 +1,19 @@
 import graphene
 
 from ..registry import registry
-
-
-class SnippetTypes:
-    # SnippetObjectType class can only be created if
-    # registry.snippets.types is non-empty, and should only be created
-    # once (graphene complains if we register multiple type classes
-    # with identical names)
-    _SnippetObjectType = None
-
-    @classmethod
-    def get_object_type(cls):
-        if cls._SnippetObjectType is None and registry.snippets:
-
-            class SnippetObjectType(graphene.Union):
-                class Meta:
-                    types = registry.snippets.types
-
-            cls._SnippetObjectType = SnippetObjectType
-        return cls._SnippetObjectType
+from .interfaces import get_snippet_interface
 
 
 def SnippetsQuery():
-    SnippetObjectType = SnippetTypes.get_object_type()
-
-    if SnippetObjectType is not None:
-
-        class Mixin:
-            snippets = graphene.List(graphene.NonNull(SnippetObjectType), required=True)
-            # Return all snippets.
-
-            def resolve_snippets(self, info, **kwargs):
-                snippet_objects = []
-                for snippet in registry.snippets:
-                    for object in snippet._meta.model.objects.all():
-                        snippet_objects.append(object)
-
-                return snippet_objects
-
-        return Mixin
+    class Mixin:
+        snippets = graphene.List(graphene.NonNull(get_snippet_interface), required=True)
 
-    else:
+        def resolve_snippets(self, info, **kwargs):
+            snippet_objects = []
+            for snippet in registry.snippets:
+                for object in snippet._meta.model.objects.all():
+                    snippet_objects.append(object)
 
-        class Mixin:
-            pass
+            return snippet_objects
 
-        return Mixin
+    return Mixin

grapple/types/streamfield.py

@@ -353,8 +353,7 @@ def resolve_items(self, info, **kwargs):
 def register_streamfield_blocks():
     from .documents import get_document_type
     from .images import get_image_type
-    from .interfaces import get_page_interface
-    from .snippets import SnippetTypes
+    from .interfaces import get_page_interface, get_snippet_interface
 
     class PageChooserBlock(graphene.ObjectType):
         page = graphene.Field(get_page_interface(), required=False)
@@ -391,20 +390,17 @@ def resolve_image(self, info, **kwargs):
         }
     )
 
-    SnippetObjectType = SnippetTypes.get_object_type()
-    if SnippetObjectType is not None:
+    class SnippetChooserBlock(graphene.ObjectType):
+        snippet = graphene.Field(get_snippet_interface(), required=False)
 
-        class SnippetChooserBlock(graphene.ObjectType):
-            snippet = graphene.Field(SnippetObjectType, required=False)
-
-            class Meta:
-                interfaces = (StreamFieldInterface,)
+        class Meta:
+            interfaces = (StreamFieldInterface,)
 
-            def resolve_snippet(self, info, **kwargs):
-                return self.value
+        def resolve_snippet(self, info, **kwargs):
+            return self.value
 
-        registry.streamfield_blocks.update(
-            {
-                wagtail.snippets.blocks.SnippetChooserBlock: SnippetChooserBlock,
-            }
-        )
+    registry.streamfield_blocks.update(
+        {
+            wagtail.snippets.blocks.SnippetChooserBlock: SnippetChooserBlock,
+        }
+    )

tests/settings_custom_page_interface.py → tests/settings_custom_interfaces.py

@@ -2,3 +2,4 @@
 
 
 GRAPPLE["PAGE_INTERFACE"] = "testapp.interfaces.CustomPageInterface"  # noqa: F405
+GRAPPLE["SNIPPET_INTERFACE"] = "testapp.interfaces.CustomSnippetInterface"  # noqa: F405