Merge pull request #1136 from python-openapi/fix/composite-schema-casting

Support parameter casting in composite schemas

Author: p1c2u

openapi_core/casting/schemas/__init__.py

@@ -1,5 +1,6 @@
 from collections import OrderedDict
 
+from openapi_core.casting.schemas.casters import AnyCaster
 from openapi_core.casting.schemas.casters import ArrayCaster
 from openapi_core.casting.schemas.casters import BooleanCaster
 from openapi_core.casting.schemas.casters import IntegerCaster
@@ -43,11 +44,11 @@
 
 oas30_types_caster = TypesCaster(
     oas30_casters_dict,
-    PrimitiveCaster,
+    AnyCaster,
 )
 oas31_types_caster = TypesCaster(
     oas31_casters_dict,
-    PrimitiveCaster,
+    AnyCaster,
     multi=PrimitiveCaster,
 )
 oas32_types_caster = oas31_types_caster

openapi_core/casting/schemas/casters.py

@@ -40,6 +40,39 @@ def cast(self, value: Any) -> Any:
         return value
 
 
+class AnyCaster(PrimitiveCaster):
+    def cast(self, value: Any) -> Any:
+        if "allOf" in self.schema:
+            for subschema in self.schema / "allOf":
+                try:
+                    # Note: Mutates `value` iteratively. This sequentially
+                    # resolves standard overlapping types but can cause edge cases
+                    # if a string is casted to an int and passed to a string schema.
+                    value = self.schema_caster.evolve(subschema).cast(value)
+                except (ValueError, TypeError, CastError):
+                    pass
+
+        if "oneOf" in self.schema:
+            for subschema in self.schema / "oneOf":
+                try:
+                    # Note: Greedy resolution. Will return the first successful
+                    # cast based on the order of the oneOf array.
+                    return self.schema_caster.evolve(subschema).cast(value)
+                except (ValueError, TypeError, CastError):
+                    pass
+
+        if "anyOf" in self.schema:
+            for subschema in self.schema / "anyOf":
+                try:
+                    # Note: Greedy resolution. Will return the first successful
+                    # cast based on the order of the anyOf array.
+                    return self.schema_caster.evolve(subschema).cast(value)
+                except (ValueError, TypeError, CastError):
+                    pass
+
+        return value
+
+
 PrimitiveType = TypeVar("PrimitiveType")
 
 

tests/unit/casting/test_schema_casters.py

@@ -66,3 +66,69 @@ def test_array_invalid_value(self, value, caster_factory):
             CastError, match=f"Failed to cast value to array type: {value}"
         ):
             caster_factory(schema).cast(value)
+
+    @pytest.mark.parametrize(
+        "composite_type,schema_type,value,expected",
+        [
+            ("allOf", "integer", "2", 2),
+            ("anyOf", "number", "3.14", 3.14),
+            ("oneOf", "boolean", "false", False),
+            ("oneOf", "boolean", "true", True),
+        ],
+    )
+    def test_composite_primitive(
+        self, caster_factory, composite_type, schema_type, value, expected
+    ):
+        spec = {
+            composite_type: [{"type": schema_type}],
+        }
+        schema = SchemaPath.from_dict(spec)
+
+        result = caster_factory(schema).cast(value)
+
+        assert result == expected
+
+    @pytest.mark.parametrize(
+        "schemas,value,expected",
+        [
+            # If string is evaluated first, it succeeds and returns string
+            ([{"type": "string"}, {"type": "integer"}], "123", "123"),
+            # If integer is evaluated first, it succeeds and returns int
+            ([{"type": "integer"}, {"type": "string"}], "123", 123),
+        ],
+    )
+    def test_oneof_greedy_casting_edge_case(
+        self, caster_factory, schemas, value, expected
+    ):
+        """
+        Documents the edge case that AnyCaster's oneOf/anyOf logic is greedy.
+        It returns the first successfully casted value based on the order in the list.
+        """
+        spec = {
+            "oneOf": schemas,
+        }
+        schema = SchemaPath.from_dict(spec)
+
+        result = caster_factory(schema).cast(value)
+
+        assert result == expected
+        # Ensure exact type matches to prevent 123 == "123" test bypass issues
+        assert type(result) is type(expected)
+
+    def test_allof_sequential_mutation_edge_case(self, caster_factory):
+        """
+        Documents the edge case that AnyCaster's allOf logic sequentially mutates the value.
+        The first schema casts "2" to an int (2). The second schema (number)
+        receives the int 2, casts it to float (2.0), and returns the float.
+        """
+        spec = {
+            "allOf": [{"type": "integer"}, {"type": "number"}],
+        }
+        schema = SchemaPath.from_dict(spec)
+        value = "2"
+
+        result = caster_factory(schema).cast(value)
+
+        # "2" -> int(2) -> float(2.0)
+        assert result == 2.0
+        assert type(result) is float