SteamField block extra interfaces (part 1) (#365)

docs/general-usage/decorators.rst

@@ -422,3 +422,18 @@ To extend the schema with custom StreamField block types, the ``register_streamf
             graphql_description = "This is a streamblock with a textblock child"
 
 If a block's ``Meta`` class has a ``graphql_description`` attribute, this value will be exposed as the ``description`` in introspection queries.
+
+To register additional interfaces for the block, add them with the ``interfaces`` argument:
+
+.. code-block:: python
+
+    import graphene
+
+
+    class CustomInterface(graphene.Interface):
+        text = graphene.String()
+
+
+    @register_streamfield_block(interfaces=(CustomInterface,))
+    class CustomInterfaceBlock(blocks.StructBlock):
+        text = blocks.TextBlock()

grapple/actions.py

@@ -2,7 +2,7 @@
 
 from collections.abc import Iterable
 from types import MethodType
-from typing import Any, Dict, Type, Union
+from typing import Any, Dict, Tuple, Type, Union
 
 import graphene
 
@@ -80,7 +80,7 @@ def import_apps():
         node_type = build_streamfield_type(
             cls,
             streamfield_type["type_prefix"],
-            streamfield_type["interface"],
+            streamfield_type["interfaces"],
             base_type,
         )
 
@@ -448,22 +448,25 @@ def custom_cls_resolver(*, cls, graphql_field):
 def build_streamfield_type(
     cls: type,
     type_prefix: str,
-    interface: graphene.Interface,
+    interfaces: Tuple[graphene.Interface],
     base_type=graphene.ObjectType,
 ):
     """
     Build a graphql type for a StreamBlock or StructBlock class
     If it has custom fields then implement them.
     """
 
+    # Alias the argument name so we can use it in the class block
+    interfaces_ = interfaces
+
     # Create a new blank node type
     class Meta:
         if hasattr(cls, "graphql_types"):
             types = [
                 registry.streamfield_blocks.get(block) for block in cls.graphql_types
             ]
         else:
-            interfaces = (interface,) if interface is not None else ()
+            interfaces = interfaces_ if interfaces_ is not None else ()
         # Add description to type if the Meta class declares it
         description = getattr(cls._meta_class, "graphql_description", None)
 

grapple/helpers.py

@@ -17,22 +17,28 @@
 field_middlewares = {}
 
 
-def register_streamfield_block(cls):
-    base_block = None
-    for block_class in inspect.getmro(cls):
-        if block_class in registry.streamfield_blocks:
-            base_block = registry.streamfield_blocks[block_class]
-
-    streamfield_types.append(
-        {
-            "cls": cls,
-            "type_prefix": "",
-            "interface": StreamFieldInterface,
-            "base_type": base_block,
-        }
-    )
-
-    return cls
+def register_streamfield_block(klass=None, interfaces=()):
+    def decorator(cls):
+        base_block = None
+        for block_class in inspect.getmro(cls):
+            if block_class in registry.streamfield_blocks:
+                base_block = registry.streamfield_blocks[block_class]
+
+        streamfield_types.append(
+            {
+                "cls": cls,
+                "type_prefix": "",
+                "interfaces": tuple({StreamFieldInterface, *interfaces}),
+                "base_type": base_block,
+            }
+        )
+
+        return cls
+
+    if isinstance(klass, type) and not interfaces:
+        return decorator(klass)
+
+    return decorator
 
 
 def register_graphql_schema(schema_cls):

tests/requirements.txt

@@ -1,6 +1,6 @@
 # Test requirements.
 black>=23.7.0
-ruff=0.0.285
+ruff==0.0.285
 
 # Runtime requirements
 Django>=3.2,<5.0

tests/test_blog.py

@@ -20,6 +20,7 @@
 from testapp.factories import (
     AdvertFactory,
     BlogPageFactory,
+    CustomInterfaceBlockFactory,
     PersonFactory,
     TextWithCallableBlockFactory,
 )
@@ -128,6 +129,7 @@ def setUp(self):
                     },
                 ),
                 ("text_with_callable", TextWithCallableBlockFactory()),
+                ("custom_interface_block", CustomInterfaceBlockFactory()),
             ],
             parent=self.home,
             summary=self.richtext_sample,
@@ -1202,3 +1204,30 @@ def test_struct_block_no_description(self):
         """
         response = self.client.execute(query)
         self.assertIsNone(response["data"]["__type"]["description"])
+
+    def test_custom_interface_block(self):
+        query = """
+        query($id: ID) {
+            page(id: $id) {
+                ... on BlogPage {
+                    body {
+                        blockType
+                        ...on CustomInterface {
+                            customText
+                        }
+                    }
+                }
+            }
+        }
+        """
+        executed = self.client.execute(query, variables={"id": self.blog_page.id})
+        body = executed["data"]["page"]["body"]
+
+        for block in body:
+            if block["blockType"] == "CustomInterfaceBlock":
+                self.assertRegex(
+                    block["customText"], r"^Block with custom interface \d+$"
+                )
+                return
+
+        self.fail("Query by interface didn't match anything")

tests/testapp/blocks.py

@@ -291,6 +291,23 @@ def get_link_url(
         return ""
 
 
+class CustomInterface(graphene.Interface):
+    custom_text = graphene.String()
+
+
+@register_streamfield_block(interfaces=(CustomInterface,))
+class CustomInterfaceBlock(blocks.StructBlock):
+    """
+    Specify a custom GraphQL interface for our block.
+    """
+
+    custom_text = blocks.TextBlock()
+
+    graphql_fields = [
+        GraphQLString("custom_text"),
+    ]
+
+
 class StreamFieldBlock(blocks.StreamBlock):
     heading = blocks.CharBlock(classname="full title")
     paragraph = blocks.RichTextBlock()
@@ -309,3 +326,4 @@ class StreamFieldBlock(blocks.StreamBlock):
     block_with_name = BlockWithName()
     advert = SnippetChooserBlock("testapp.Advert")
     person = SnippetChooserBlock("testapp.Person")
+    custom_interface_block = CustomInterfaceBlock()

tests/testapp/factories.py

@@ -7,6 +7,7 @@
 from wagtail import blocks
 
 from testapp.blocks import (
+    CustomInterfaceBlock,
     ImageGalleryBlock,
     ImageGalleryImage,
     ImageGalleryImages,
@@ -85,6 +86,13 @@ class Meta:
         model = TextWithCallableBlock
 
 
+class CustomInterfaceBlockFactory(wagtail_factories.StructBlockFactory):
+    custom_text = factory.Sequence(lambda n: f"Block with custom interface {n}")
+
+    class Meta:
+        model = CustomInterfaceBlock
+
+
 class BlogPageRelatedLinkFactory(factory.django.DjangoModelFactory):
     class Meta:
         model = BlogPageRelatedLink