Add support for custom JSON Schema instance formats defined by users

mashumaro/jsonschema/models.py

@@ -8,6 +8,7 @@
 from typing_extensions import TYPE_CHECKING, Self, TypeAlias
 
 from mashumaro.config import BaseConfig
+from mashumaro.core.meta.helpers import iter_all_subclasses
 from mashumaro.helper import pass_through
 from mashumaro.jsonschema.dialects import DRAFT_2020_12, JSONSchemaDialect
 
@@ -96,16 +97,23 @@ class JSONSchemaInstanceFormatExtension(JSONSchemaInstanceFormat):
 }
 
 
+def _deserialize_json_schema_instance_format(value):
+    for cls in iter_all_subclasses(JSONSchemaInstanceFormat):
+        try:
+            return cls(value)
+        except (ValueError, TypeError):
+            pass
+    raise ValueError(value)
+
+
 @dataclass(unsafe_hash=True)
 class JSONSchema(DataClassJSONMixin):
     # Common keywords
     schema: Optional[str] = None
     type: Optional[JSONSchemaInstanceType] = None
     enum: Optional[list[Any]] = None
     const: Optional[Any] = field(default_factory=lambda: MISSING)
-    format: Optional[
-        Union[JSONSchemaStringFormat, JSONSchemaInstanceFormatExtension]
-    ] = None
+    format: Optional[JSONSchemaInstanceFormat] = None
     title: Optional[str] = None
     description: Optional[str] = None
     anyOf: Optional[List["JSONSchema"]] = None
@@ -157,6 +165,9 @@ class Config(BaseConfig):
             int: pass_through,
             float: pass_through,
             Null: pass_through,
+            JSONSchemaInstanceFormat: {
+                "deserialize": _deserialize_json_schema_instance_format,
+            }
         }
 
     def __pre_serialize__(self) -> Self:

tests/test_jsonschema/test_jsonschema_generation.py

@@ -65,14 +65,21 @@
 from mashumaro.jsonschema.builder import JSONSchemaBuilder, build_json_schema
 from mashumaro.jsonschema.dialects import DRAFT_2020_12, OPEN_API_3_1
 from mashumaro.jsonschema.models import (
+    BasePlugin,
+    Context,
     JSONArraySchema,
     JSONObjectSchema,
     JSONSchema,
+    JSONSchemaInstanceFormat,
     JSONSchemaInstanceFormatExtension,
     JSONSchemaInstanceType,
     JSONSchemaStringFormat,
 )
-from mashumaro.jsonschema.schema import UTC_OFFSET_PATTERN, EmptyJSONSchema
+from mashumaro.jsonschema.schema import (
+    UTC_OFFSET_PATTERN,
+    EmptyJSONSchema,
+    Instance,
+)
 from mashumaro.types import Discriminator, SerializationStrategy
 from tests.entities import (
     CustomPath,
@@ -1354,3 +1361,79 @@ class Main:
         additionalProperties=False,
     )
     assert build_json_schema(Main) == schema
+
+
+def test_jsonschema_with_custom_instance_format():
+    class CustomJSONSchemaInstanceFormatPlugin(BasePlugin):
+        def get_schema(
+            self,
+            instance: Instance,
+            ctx: Context,
+            schema: Optional[JSONSchema] = None,
+        ) -> Optional[JSONSchema]:
+            for annotation in instance.annotations:
+                if isinstance(annotation, JSONSchemaInstanceFormat):
+                    schema.format = annotation
+            return schema
+
+    class Custom1InstanceFormat(JSONSchemaInstanceFormat):
+        CUSTOM1 = "custom1"
+
+    class CustomInstanceFormatBase(JSONSchemaInstanceFormat):
+        pass
+
+    class Custom2InstanceFormat(CustomInstanceFormatBase):
+        CUSTOM2 = "custom2"
+
+    type1 = Annotated[str, Custom1InstanceFormat.CUSTOM1]
+    schema1 = build_json_schema(
+        type1, plugins=[CustomJSONSchemaInstanceFormatPlugin()]
+    )
+    assert schema1.format is Custom1InstanceFormat.CUSTOM1
+    assert schema1.to_dict()["format"] == "custom1"
+
+    type2 = Annotated[int, Custom2InstanceFormat.CUSTOM2]
+    schema2 = build_json_schema(
+        type2, plugins=[CustomJSONSchemaInstanceFormatPlugin()]
+    )
+    assert schema2.format is Custom2InstanceFormat.CUSTOM2
+    assert schema2.to_dict()["format"] == "custom2"
+
+    assert (
+        JSONSchema.from_dict({"format": "custom1"}).format
+        is Custom1InstanceFormat.CUSTOM1
+    )
+    assert (
+        JSONSchema.from_dict({"format": "custom2"}).format
+        is Custom2InstanceFormat.CUSTOM2
+    )
+
+    @dataclass
+    class MyClass:
+        x: str
+        y: str
+
+        class Config(BaseConfig):
+            json_schema = {
+                "properties": {
+                    "x": {"type": "string", "format": "custom1"},
+                    "y": {"type": "string", "format": "custom2"},
+                }
+            }
+
+    schema3 = build_json_schema(MyClass)
+    assert schema3 == JSONObjectSchema(
+        title="MyClass",
+        properties={
+            "x": JSONSchema(
+                type=JSONSchemaInstanceType.STRING,
+                format=Custom1InstanceFormat.CUSTOM1,
+            ),
+            "y": JSONSchema(
+                type=JSONSchemaInstanceType.STRING,
+                format=Custom2InstanceFormat.CUSTOM2,
+            ),
+        },
+        required=["x", "y"],
+        additionalProperties=False,
+    )