fix(SchemaGenerator): exclude inherited properties only when base add…

src/Swashbuckle.AspNetCore.SwaggerGen/SchemaGenerator/SchemaGenerator.cs

@@ -405,7 +405,8 @@ private OpenApiSchema CreateObjectSchema(DataContract dataContract, SchemaReposi
                 }
 
                 applicableDataProperties = applicableDataProperties
-                    .Where(dataProperty => dataProperty.MemberInfo.DeclaringType == dataContract.UnderlyingType);
+                    // if the property is declared on a type other than (the one we just added as a base or one of its parents)
+                    .Where(dataProperty => !baseTypeDataContract.UnderlyingType.IsAssignableTo(dataProperty.MemberInfo.DeclaringType));
             }
 
             if (IsBaseTypeWithKnownTypesDefined(dataContract, out var knownTypesDataContracts))

test/Swashbuckle.AspNetCore.SwaggerGen.Test/Fixtures/FakeControllerWithInheritance.cs

@@ -0,0 +1,35 @@
+using Microsoft.AspNetCore.Mvc;
+
+namespace Swashbuckle.AspNetCore.SwaggerGen.Test;
+
+public class FakeControllerWithInheritance
+{
+    public void ActionWithDerivedObjectParameter([FromBody] AbcTests_C param)
+    { }
+
+    public List<AbcTests_A> ActionWithDerivedObjectResponse()
+    {
+        return null!;
+    }
+
+    public AbcTests_B ActionWithDerivedObjectResponse_ExcludedFromInheritanceConfig()
+    {
+        return null!;
+    }
+
+    // Helper test types for GenerateSchema_PreservesIntermediateBaseProperties_WhenUsingOneOfPolymorphism
+    public abstract class AbcTests_A
+    {
+        public string PropA { get; set; }
+    }
+
+    public class AbcTests_B : AbcTests_A
+    {
+        public string PropB { get; set; }
+    }
+
+    public class AbcTests_C : AbcTests_B
+    {
+        public string PropC { get; set; }
+    }
+}

test/Swashbuckle.AspNetCore.SwaggerGen.Test/SchemaGenerator/JsonSerializerSchemaGeneratorTests.cs

@@ -717,6 +717,60 @@ public void GenerateSchema_SupportsOption_UseAllOfForPolymorphism()
         Assert.Equal(["Property2"], subType2Schema.Properties.Keys);
     }
 
+    [Fact]
+    public void GenerateSchema_PreservesIntermediateBaseProperties_WhenUsingOneOfPolymorphism()
+    {
+        // Arrange - define a type hierarchy A <- B <- C where only A and C are selected as known subtypes
+        var subject = Subject(configureGenerator: c =>
+        {
+            c.UseOneOfForPolymorphism = true;
+            c.SubTypesSelector = (type) => type == typeof(AbcTests_A) ? new[] { typeof(AbcTests_C) } : Array.Empty<Type>();
+        });
+
+        var schemaRepository = new SchemaRepository();
+
+        // Act
+        var schema = subject.GenerateSchema(typeof(AbcTests_A), schemaRepository);
+
+        // Assert - polymorphic schema should be present
+        Assert.NotNull(schema.OneOf);
+
+        // Ensure base A schema contains PropA
+        Assert.True(schemaRepository.Schemas.ContainsKey(nameof(AbcTests_A)));
+        var aSchema = schemaRepository.Schemas[nameof(AbcTests_A)];
+        Assert.True(aSchema.Properties.ContainsKey(nameof(AbcTests_A.PropA)));
+
+        // Find the C schema in the OneOf and assert it preserves B's properties while not duplicating A's
+        var cRef = schema.OneOf
+            .OfType<OpenApiSchemaReference>()
+            .First(r => r.Reference.Id == nameof(AbcTests_C));
+
+        var cSchema = schemaRepository.Schemas[nameof(AbcTests_C)];
+
+        // C should include PropC and properties declared on intermediate B
+        Assert.True(cSchema.Properties.ContainsKey(nameof(AbcTests_C.PropC)));
+        Assert.True(cSchema.Properties.ContainsKey(nameof(AbcTests_B.PropB)));
+
+        // A's property should not be in C's inline properties because it's provided by the referenced base schema
+        Assert.False(cSchema.Properties.ContainsKey(nameof(AbcTests_A.PropA)));
+    }
+
+    // Helper test types for the A/B/C regression
+    public abstract class AbcTests_A
+    {
+        public string PropA { get; set; }
+    }
+
+    public class AbcTests_B : AbcTests_A
+    {
+        public string PropB { get; set; }
+    }
+
+    public class AbcTests_C : AbcTests_B
+    {
+        public string PropC { get; set; }
+    }
+
     [Fact]
     public void GenerateSchema_SupportsOption_UseAllOfToExtendReferenceSchemas()
     {

test/Swashbuckle.AspNetCore.SwaggerGen.Test/VerifyTests.cs

@@ -1112,6 +1112,146 @@ public async Task ActionHavingFromFormAttributeWithSwaggerIgnore()
         await Verify(document);
     }
 
+    [Fact]
+    public async Task GenerateSchema_PreservesIntermediateBaseProperties_WhenUsingOneOfPolymorphism()
+    {
+        var subject = Subject(
+            apiDescriptions:
+            [
+                ApiDescriptionFactory.Create<FakeControllerWithInheritance>(
+                    c => nameof(c.ActionWithDerivedObjectParameter),
+                    groupName: "v1",
+                    httpMethod: "POST",
+                    relativePath: "resource",
+                    parameterDescriptions:
+                    [
+                        new ApiParameterDescription
+                        {
+                            Name = "param1",
+                            Source = BindingSource.Body,
+                            Type = typeof(FakeControllerWithInheritance.AbcTests_C), // most derived type
+                            ModelMetadata = ModelMetadataFactory.CreateForType(typeof(FakeControllerWithInheritance.AbcTests_C)),
+                        },
+                    ],
+                    supportedRequestFormats:
+                    [
+                        new ApiRequestFormat { MediaType = "application/json" },
+                    ]),
+                ApiDescriptionFactory.Create<FakeControllerWithInheritance>(
+                    c => nameof(c.ActionWithDerivedObjectResponse),
+                    groupName: "v1",
+                    httpMethod: "GET",
+                    relativePath: "resource",
+                    parameterDescriptions: [],
+                    supportedResponseTypes: [
+                        new ApiResponseType
+                        {
+                            ApiResponseFormats = [new ApiResponseFormat { MediaType = "application/json" }],
+                            StatusCode = 200,
+                            Type = typeof(FakeControllerWithInheritance.AbcTests_A),
+                        },
+                    ]),
+                ApiDescriptionFactory.Create<FakeControllerWithInheritance>(
+                    c => nameof(c.ActionWithDerivedObjectResponse_ExcludedFromInheritanceConfig),
+                    groupName: "v1",
+                    httpMethod: "GET",
+                    relativePath: "resourceB",
+                    parameterDescriptions: [],
+                    supportedResponseTypes: [
+                        new ApiResponseType
+                        {
+                            ApiResponseFormats = [new ApiResponseFormat { MediaType = "application/json" }],
+                            StatusCode = 200,
+                            Type = typeof(FakeControllerWithInheritance.AbcTests_B),
+                        },
+                    ]),
+            ],
+            configureSchemaGeneratorOptions: c =>
+            {
+                c.UseOneOfForPolymorphism = true;
+                c.SubTypesSelector =
+                    (type) => (Type[])(
+                        type == typeof(FakeControllerWithInheritance.AbcTests_A)
+                            ? [typeof(FakeControllerWithInheritance.AbcTests_C)]
+                            : []
+                    );
+            }
+        );
+        var document = subject.GetSwagger("v1");
+
+        await Verify(document);
+    }
+
+    [Fact]
+    public async Task GenerateSchema_PreservesMultiLevelInheritance()
+    {
+        var subject = Subject(
+            apiDescriptions:
+            [
+                ApiDescriptionFactory.Create<FakeControllerWithInheritance>(
+                    c => nameof(c.ActionWithDerivedObjectParameter),
+                    groupName: "v1",
+                    httpMethod: "POST",
+                    relativePath: "resource",
+                    parameterDescriptions:
+                    [
+                        new ApiParameterDescription
+                        {
+                            Name = "param1",
+                            Source = BindingSource.Body,
+                            Type = typeof(FakeControllerWithInheritance.AbcTests_C), // most derived type
+                            ModelMetadata = ModelMetadataFactory.CreateForType(typeof(FakeControllerWithInheritance.AbcTests_C)),
+                        },
+                    ],
+                    supportedRequestFormats:
+                    [
+                        new ApiRequestFormat { MediaType = "application/json" },
+                    ]),
+                ApiDescriptionFactory.Create<FakeControllerWithInheritance>(
+                    c => nameof(c.ActionWithDerivedObjectResponse),
+                    groupName: "v1",
+                    httpMethod: "GET",
+                    relativePath: "resource",
+                    parameterDescriptions: [],
+                    supportedResponseTypes: [
+                        new ApiResponseType
+                        {
+                            ApiResponseFormats = [new ApiResponseFormat { MediaType = "application/json" }],
+                            StatusCode = 200,
+                            Type = typeof(FakeControllerWithInheritance.AbcTests_A),
+                        },
+                    ]),
+                ApiDescriptionFactory.Create<FakeControllerWithInheritance>(
+                    c => nameof(c.ActionWithDerivedObjectResponse_ExcludedFromInheritanceConfig),
+                    groupName: "v1",
+                    httpMethod: "GET",
+                    relativePath: "resourceB",
+                    parameterDescriptions: [],
+                    supportedResponseTypes: [
+                        new ApiResponseType
+                        {
+                            ApiResponseFormats = [new ApiResponseFormat { MediaType = "application/json" }],
+                            StatusCode = 200,
+                            Type = typeof(FakeControllerWithInheritance.AbcTests_B),
+                        },
+                    ]),
+            ],
+            configureSchemaGeneratorOptions: c =>
+            {
+                c.UseOneOfForPolymorphism = true;
+                c.SubTypesSelector =
+                    (type) => (Type[])(
+                        type == typeof(FakeControllerWithInheritance.AbcTests_A) ? [typeof(FakeControllerWithInheritance.AbcTests_B), typeof(FakeControllerWithInheritance.AbcTests_C)]
+                        : type == typeof(FakeControllerWithInheritance.AbcTests_B) ? [typeof(FakeControllerWithInheritance.AbcTests_C)]
+                        : []
+                    );
+            }
+        );
+        var document = subject.GetSwagger("v1");
+
+        await Verify(document);
+    }
+
     [Fact]
     public async Task GetSwagger_Works_As_Expected_When_FromFormObject()
     {
@@ -1465,12 +1605,16 @@ private static SwaggerGenerator Subject(
             IEnumerable<ApiDescription> apiDescriptions,
             SwaggerGeneratorOptions options = null,
             IEnumerable<AuthenticationScheme> authenticationSchemes = null,
-            List<ISchemaFilter> schemaFilters = null)
+            List<ISchemaFilter> schemaFilters = null,
+            Action<SchemaGeneratorOptions> configureSchemaGeneratorOptions = null)
     {
+        var schemaGeneratorOptions = new SchemaGeneratorOptions() { SchemaFilters = schemaFilters ?? [] };
+        configureSchemaGeneratorOptions?.Invoke(schemaGeneratorOptions);
+
         return new SwaggerGenerator(
             options ?? DefaultOptions,
             new FakeApiDescriptionGroupCollectionProvider(apiDescriptions),
-            new SchemaGenerator(new SchemaGeneratorOptions() { SchemaFilters = schemaFilters ?? [] }, new JsonSerializerDataContractResolver(new JsonSerializerOptions())),
+            new SchemaGenerator(schemaGeneratorOptions, new JsonSerializerDataContractResolver(new JsonSerializerOptions())),
             new FakeAuthenticationSchemeProvider(authenticationSchemes ?? [])
         );
     }

test/Swashbuckle.AspNetCore.SwaggerGen.Test/snapshots/VerifyTests.GenerateSchema_PreservesIntermediateBaseProperties_WhenUsingOneOfPolymorphism.DotNet10_0.verified.txt

@@ -0,0 +1,125 @@
+{
+  "openapi": "3.0.4",
+  "info": {
+    "title": "Test API",
+    "version": "V1"
+  },
+  "paths": {
+    "/resource": {
+      "post": {
+        "tags": [
+          "FakeWithInheritance"
+        ],
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/AbcTests_C"
+              }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "OK"
+          }
+        }
+      },
+      "get": {
+        "tags": [
+          "FakeWithInheritance"
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "array",
+                  "items": {
+                    "oneOf": [
+                      {
+                        "$ref": "#/components/schemas/AbcTests_C"
+                      }
+                    ]
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    },
+    "/resourceB": {
+      "get": {
+        "tags": [
+          "FakeWithInheritance"
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/AbcTests_B"
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "components": {
+    "schemas": {
+      "AbcTests_A": {
+        "type": "object",
+        "properties": {
+          "PropA": {
+            "type": "string",
+            "nullable": true
+          }
+        },
+        "additionalProperties": false
+      },
+      "AbcTests_B": {
+        "type": "object",
+        "properties": {
+          "PropA": {
+            "type": "string",
+            "nullable": true
+          },
+          "PropB": {
+            "type": "string",
+            "nullable": true
+          }
+        },
+        "additionalProperties": false
+      },
+      "AbcTests_C": {
+        "type": "object",
+        "allOf": [
+          {
+            "$ref": "#/components/schemas/AbcTests_A"
+          }
+        ],
+        "properties": {
+          "PropB": {
+            "type": "string",
+            "nullable": true
+          },
+          "PropC": {
+            "type": "string",
+            "nullable": true
+          }
+        },
+        "additionalProperties": false
+      }
+    }
+  },
+  "tags": [
+    {
+      "name": "FakeWithInheritance"
+    }
+  ]
+}