Add support for JsonPolymorphic and JsonDerivedType attributes to Swashbuckle.AspNetCore.Annotations for .NET7 and later

README.md

@@ -1165,7 +1165,7 @@ services.AddSwaggerGen(c =>
 });
 ```
 
-_NOTE: If you're using the [Swashbuckle Annotations library](#swashbuckleaspnetcoreannotations), it contains a custom selector that's based on the presence of `SwaggerSubType` attributes on base class definitions. This way, you can use simple attributes to explicitly list the inheritance and/or polymorphism relationships you want to expose. To enable this behavior, check out the [Annotations docs](#list-known-subtypes-for-inheritance-and-polymorphism)._
+_NOTE: If you're using the [Swashbuckle Annotations library](#swashbuckleaspnetcoreannotations), it contains a custom selector that's based on the presence of `JsonDerivedType` (or `SwaggerSubType` for .NET 6 or earlier) attributes on base class definitions. This way, you can use simple attributes to explicitly list the inheritance and/or polymorphism relationships you want to expose. To enable this behavior, check out the [Annotations docs](#list-known-subtypes-for-inheritance-and-polymorphism)._
 
 #### Describing Discriminators ####
 
@@ -1231,7 +1231,7 @@ services.AddSwaggerGen(c =>
 });
 ```
 
-_NOTE: If you're using the [Swashbuckle Annotations library](#swashbuckleaspnetcoreannotations), it contains custom selector functions that are based on the presence of `SwaggerDiscriminator` and `SwaggerSubType` attributes on base class definitions. This way, you can use simple attributes to explicitly provide discriminator metadata. To enable this behavior, check out the [Annotations docs](#enrich-polymorphic-base-classes-with-discriminator-metadata)._
+_NOTE: If you're using the [Swashbuckle Annotations library](#swashbuckleaspnetcoreannotations), it contains custom selector functions that are based on the presence of `JsonPolymorphic` (or `SwaggerDiscriminator` for .NET 6 or earlier) and `JsonDerivedType` (or `SwaggerSubType` for .NET 6 or earlier) attributes on base class definitions. This way, you can use simple attributes to explicitly provide discriminator metadata. To enable this behavior, check out the [Annotations docs](#enrich-polymorphic-base-classes-with-discriminator-metadata)._
 
 ## Swashbuckle.AspNetCore.SwaggerUI ##
 
@@ -1539,6 +1539,15 @@ services.AddSwaggerGen(c =>
 });
 
 // Shape.cs
+
+// .NET 7 or later
+[JsonDerivedType(typeof(Rectangle))]
+[JsonDerivedType(typeof(Circle))]
+public abstract class Shape
+{
+}
+
+// .NET 6 or earlier
 [SwaggerSubType(typeof(Rectangle))]
 [SwaggerSubType(typeof(Circle))]
 public abstract class Shape
@@ -1548,7 +1557,7 @@ public abstract class Shape
 
 ### Enrich Polymorphic Base Classes with Discriminator Metadata ###
 
-If you're using annotations to _explicitly_ indicate the "known" subtypes for a polymorphic base type, you can combine the `SwaggerDiscriminatorAttribute` with the `SwaggerSubTypeAttribute` to provide additional metadata about the "discriminator" property, which will then be incorporated into the generated schema definition:
+If you're using annotations to _explicitly_ indicate the "known" subtypes for a polymorphic base type, you can combine the `JsonPolymorphicAttribute` with the `JsonDerivedTypeAttribute` to provide additional metadata about the "discriminator" property, which will then be incorporated into the generated schema definition:
 
 
 ```csharp
@@ -1559,12 +1568,32 @@ services.AddSwaggerGen(c =>
 });
 
 // Shape.cs
+
+// .NET 7 or later
+[JsonPolymorphic(TypeDiscriminatorPropertyName = "shapeType")]
+[JsonDerivedType(typeof(Rectangle), "rectangle")]
+[JsonDerivedType(typeof(Circle), "circle")]
+public abstract class Shape
+{
+    // Avoid using a JsonPolymorphicAttribute.TypeDiscriminatorPropertyName
+    // that conflicts with a property in your type hierarchy.
+    // Related issue: https://github.com/dotnet/runtime/issues/72170
+}
+
+// .NET 6 or earlier
 [SwaggerDiscriminator("shapeType")]
 [SwaggerSubType(typeof(Rectangle), DiscriminatorValue = "rectangle")]
 [SwaggerSubType(typeof(Circle), DiscriminatorValue = "circle")]
 public abstract class Shape
 {
-    public ShapeType { get; set; }
+    public ShapeType ShapeType { get; set; }
+}
+
+[JsonConverter(typeof(JsonStringEnumConverter))]
+public enum ShapeType
+{
+    Circle,
+    Rectangle
 }
 ```
 

src/Swashbuckle.AspNetCore.Annotations/AnnotationsSwaggerGenOptionsExtensions.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Text.Json.Serialization;
 using Swashbuckle.AspNetCore.SwaggerGen;
 using Swashbuckle.AspNetCore.Annotations;
 
@@ -56,8 +57,22 @@ public static void EnableAnnotations(this SwaggerGenOptions options)
 
         private static IEnumerable<Type> AnnotationsSubTypesSelector(Type type)
         {
+#if NET7_0_OR_GREATER
+            var jsonDerivedTypeAttributes = type.GetCustomAttributes(false)
+                .OfType<JsonDerivedTypeAttribute>()
+                .ToArray();
+
+            if (jsonDerivedTypeAttributes.Any())
+            {
+                return jsonDerivedTypeAttributes.Select(attr => attr.DerivedType);
+            }
+#endif
+
+#pragma warning disable CS0618 // Type or member is obsolete
             var subTypeAttributes = type.GetCustomAttributes(false)
-                .OfType<SwaggerSubTypeAttribute>();
+                .OfType<SwaggerSubTypeAttribute>()
+                .ToArray();
+#pragma warning restore CS0618 // Type or member is obsolete
 
             if (subTypeAttributes.Any())
             {
@@ -80,9 +95,22 @@ private static IEnumerable<Type> AnnotationsSubTypesSelector(Type type)
 
         private static string AnnotationsDiscriminatorNameSelector(Type baseType)
         {
+#if NET7_0_OR_GREATER
+            var jsonPolymorphicAttribute = baseType.GetCustomAttributes(false)
+                .OfType<JsonPolymorphicAttribute>()
+                .FirstOrDefault();
+
+            if (jsonPolymorphicAttribute is not null)
+            {
+                return jsonPolymorphicAttribute.TypeDiscriminatorPropertyName;
+            }
+#endif
+
+#pragma warning disable CS0618 // Type or member is obsolete
             var discriminatorAttribute = baseType.GetCustomAttributes(false)
                 .OfType<SwaggerDiscriminatorAttribute>()
                 .FirstOrDefault();
+#pragma warning restore CS0618 // Type or member is obsolete
 
             if (discriminatorAttribute != null)
             {
@@ -108,9 +136,22 @@ private static string AnnotationsDiscriminatorValueSelector(Type subType)
             if (subType.BaseType == null)
                 return null;
 
+#if NET7_0_OR_GREATER
+            var jsonDerivedTypeAttribute = subType.BaseType.GetCustomAttributes(false)
+                .OfType<JsonDerivedTypeAttribute>()
+                .FirstOrDefault(attr => attr.DerivedType == subType);
+
+            if (jsonDerivedTypeAttribute is not null)
+            {
+                return jsonDerivedTypeAttribute.TypeDiscriminator?.ToString();
+            }
+#endif
+
+#pragma warning disable CS0618 // Type or member is obsolete
             var subTypeAttribute = subType.BaseType.GetCustomAttributes(false)
                 .OfType<SwaggerSubTypeAttribute>()
                 .FirstOrDefault(attr => attr.SubType == subType);
+#pragma warning restore CS0618 // Type or member is obsolete
 
             if (subTypeAttribute != null)
             {

test/Swashbuckle.AspNetCore.IntegrationTests/SwaggerVerifyIntegrationTest.cs

@@ -19,6 +19,7 @@ public partial class SwaggerVerifyIntegrationTest
         [InlineData(typeof(GenericControllers.Startup), "/swagger/v1/swagger.json")]
         [InlineData(typeof(MultipleVersions.Startup), "/swagger/1.0/swagger.json")]
         [InlineData(typeof(MultipleVersions.Startup), "/swagger/2.0/swagger.json")]
+        [InlineData(typeof(NSwagClientExample.Startup), "/swagger/v1/swagger.json")]
         [InlineData(typeof(OAuth2Integration.Startup), "/resource-server/swagger/v1/swagger.json")]
         [InlineData(typeof(ReDocApp.Startup), "/swagger/v1/swagger.json")]
         [InlineData(typeof(TestFirst.Startup), "/swagger/v1-generated/openapi.json")]

test/Swashbuckle.AspNetCore.IntegrationTests/Swashbuckle.AspNetCore.IntegrationTests.csproj

@@ -16,6 +16,7 @@
     <ProjectReference Include="..\WebSites\CustomUIIndex\CustomUIIndex.csproj" />
     <ProjectReference Include="..\WebSites\GenericControllers\GenericControllers.csproj" />
     <ProjectReference Include="..\WebSites\MultipleVersions\MultipleVersions.csproj" />
+    <ProjectReference Include="..\WebSites\NswagClientExample\NswagClientExample.csproj" />
     <ProjectReference Include="..\WebSites\OAuth2Integration\OAuth2Integration.csproj" />
     <ProjectReference Include="..\WebSites\ReDoc\ReDoc.csproj" />
     <ProjectReference Include="..\WebSites\TestFirst\TestFirst.csproj" />

test/WebSites/NswagClientExample/Controllers/PaymentMethodsController.cs

@@ -0,0 +1,37 @@
+#if NET7_0_OR_GREATER
+using System;
+using System.ComponentModel.DataAnnotations;
+using System.Text.Json.Serialization;
+using Microsoft.AspNetCore.Mvc;
+
+namespace NSwagClientExample.Controllers
+{
+    [ApiController]
+    [Route("[controller]")]
+    public class PaymentMethodsController : ControllerBase
+    {
+        [HttpPost]
+        public void AddPaymentMethod([Required]PaymentMethod paymentMethod)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    [JsonPolymorphic(TypeDiscriminatorPropertyName = "paymentMethod")]
+    [JsonDerivedType(typeof(CreditCard), "CreditCard")]
+    [JsonDerivedType(typeof(MobileWallet), "MobileWallet")]
+    public class PaymentMethod
+    {
+    }
+
+    public class CreditCard : PaymentMethod
+    {
+        public string CardNumber { get; set; }
+    }
+
+    public class MobileWallet : PaymentMethod
+    {
+        public string WalletId { get; set; }
+    }
+}
+#endif

test/WebSites/NswagClientExample/swagger_net8.0.json

@@ -71,6 +71,68 @@
           }
         }
       }
+    },
+    "/PaymentMethods": {
+      "post": {
+        "tags": [
+          "PaymentMethods"
+        ],
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "oneOf": [
+                  {
+                    "$ref": "#/components/schemas/PaymentMethod"
+                  },
+                  {
+                    "$ref": "#/components/schemas/CreditCard"
+                  },
+                  {
+                    "$ref": "#/components/schemas/MobileWallet"
+                  }
+                ]
+              }
+            },
+            "text/json": {
+              "schema": {
+                "oneOf": [
+                  {
+                    "$ref": "#/components/schemas/PaymentMethod"
+                  },
+                  {
+                    "$ref": "#/components/schemas/CreditCard"
+                  },
+                  {
+                    "$ref": "#/components/schemas/MobileWallet"
+                  }
+                ]
+              }
+            },
+            "application/*+json": {
+              "schema": {
+                "oneOf": [
+                  {
+                    "$ref": "#/components/schemas/PaymentMethod"
+                  },
+                  {
+                    "$ref": "#/components/schemas/CreditCard"
+                  },
+                  {
+                    "$ref": "#/components/schemas/MobileWallet"
+                  }
+                ]
+              }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "200": {
+            "description": "OK"
+          }
+        }
+      }
     }
   },
   "components": {
@@ -118,6 +180,23 @@
           }
         ]
       },
+      "CreditCard": {
+        "allOf": [
+          {
+            "$ref": "#/components/schemas/PaymentMethod"
+          },
+          {
+            "type": "object",
+            "properties": {
+              "cardNumber": {
+                "type": "string",
+                "nullable": true
+              }
+            },
+            "additionalProperties": false
+          }
+        ]
+      },
       "Dog": {
         "allOf": [
           {
@@ -134,6 +213,42 @@
             "additionalProperties": false
           }
         ]
+      },
+      "MobileWallet": {
+        "allOf": [
+          {
+            "$ref": "#/components/schemas/PaymentMethod"
+          },
+          {
+            "type": "object",
+            "properties": {
+              "walletId": {
+                "type": "string",
+                "nullable": true
+              }
+            },
+            "additionalProperties": false
+          }
+        ]
+      },
+      "PaymentMethod": {
+        "required": [
+          "paymentMethod"
+        ],
+        "type": "object",
+        "properties": {
+          "paymentMethod": {
+            "type": "string"
+          }
+        },
+        "additionalProperties": false,
+        "discriminator": {
+          "propertyName": "paymentMethod",
+          "mapping": {
+            "CreditCard": "#/components/schemas/CreditCard",
+            "MobileWallet": "#/components/schemas/MobileWallet"
+          }
+        }
       }
     }
   }