[IDP-1424] Only return application/json content type for Typed respon…

…ses (#16)

* [IDP-1424] Only return application/json content type for Typed responses

* Update readme

README.md

@@ -161,7 +161,8 @@ public Ok<TypedResultExample> EnforceStronglyTypedResponse() //This is a strongl
 
 ### Limitations
 
-We currently only support the extraction of the default media type and not any globally defined content types such as [`{ "application/json", "text/json", "text/plain", }`](https://learn.microsoft.com/en-us/aspnet/core/web-api/advanced/formatting?view=aspnetcore-8.0)
+[Given that HttpResults return types do not leverage the configured Formatters](https://learn.microsoft.com/en-us/aspnet/core/web-api/action-return-types?view=aspnetcore-8.0#httpresults-type), content negotiation is not supported for these endpoints and the produced Content-Type is decided by HttpResults implementation. For our use cases, it will be `application/json`.
+
 
 ## Building, releasing and versioning
 

src/Workleap.Extensions.OpenAPI/TypedResult/ExtractSchemaTypeResultFilter.cs

@@ -1,4 +1,3 @@
-using System.Reflection;
 using Microsoft.AspNetCore.Http;
 using Microsoft.OpenApi.Models;
 using Swashbuckle.AspNetCore.SwaggerGen;
@@ -8,11 +7,10 @@ namespace Workleap.Extensions.OpenAPI.TypedResult;
 internal sealed class ExtractSchemaTypeResultFilter : IOperationFilter
 {
     // Based on this documentation: https://learn.microsoft.com/en-us/aspnet/core/web-api/advanced/formatting?view=aspnetcore-8.0
-    private static readonly IReadOnlyList<string> DefaultContentTypes = new List<string>() { "application/json", "text/json", "text/plain", };
+    private const string DefaultContentType = "application/json";
 
     public void Apply(OpenApiOperation operation, OperationFilterContext context)
     {
-        var contentTypes = GetContentTypes(context);
         foreach (var responseMetadata in GetResponsesMetadata(context.MethodInfo.ReturnType))
         {
             // If the response content is already set, we won't overwrite it. This is the case for minimal APIs and
@@ -33,41 +31,13 @@ public void Apply(OpenApiOperation operation, OperationFilterContext context)
             if (responseMetadata.SchemaType != null)
             {
                 var schema = context.SchemaGenerator.GenerateSchema(responseMetadata.SchemaType, context.SchemaRepository);
-
-                foreach (var contentType in contentTypes)
-                {
-                    response.Content.Add(contentType, new OpenApiMediaType { Schema = schema });
-                }
+                response.Content.Add(DefaultContentType, new OpenApiMediaType { Schema = schema });
             }
 
             operation.Responses[responseMetadata.HttpCode.ToString()] = response;
         }
     }
 
-    private static IReadOnlyCollection<string> GetContentTypes(OperationFilterContext context)
-    {
-        var methodProducesAttribute = context.MethodInfo.GetCustomAttribute<Microsoft.AspNetCore.Mvc.ProducesAttribute>();
-        if (methodProducesAttribute != null)
-        {
-            return methodProducesAttribute.ContentTypes.ToList();
-        }
-
-        var controllerProducesAttribute = context.MethodInfo.DeclaringType?.GetCustomAttribute<Microsoft.AspNetCore.Mvc.ProducesAttribute>();
-        if (controllerProducesAttribute != null)
-        {
-            return controllerProducesAttribute.ContentTypes.ToList();
-        }
-
-        var endpointProducesAttribute = context.ApiDescription.ActionDescriptor.EndpointMetadata.OfType<Microsoft.AspNetCore.Mvc.ProducesAttribute>().FirstOrDefault();
-        if (endpointProducesAttribute != null)
-        {
-            return endpointProducesAttribute.ContentTypes.ToList();
-        }
-
-        // Fallback on default content types, not supporting globally defined content types
-        return DefaultContentTypes;
-    }
-
     internal static IEnumerable<ResponseMetadata> GetResponsesMetadata(Type returnType)
     {
         // Unwrap Task<> to get the return type

src/tests/WebApi.OpenAPI.SystemTest/ExtractTypeResult/TypedResultNoProducesController.cs

@@ -0,0 +1,15 @@
+using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.AspNetCore.Mvc;
+
+namespace WebApi.OpenAPI.SystemTest.ExtractTypeResult;
+
+public class TypedResultNoProducesController
+{
+    [HttpGet]
+    [Route("/useApplicationJsonContentType")]
+    [ProducesResponseType<string>(StatusCodes.Status200OK, "text/plain")]
+    public Ok<string> TypedResultUseApplicationJsonContentType()
+    {
+        return TypedResults.Ok("example");
+    }
+}

src/tests/WebApi.OpenAPI.SystemTest/openapi-v1.yaml

@@ -407,6 +407,17 @@ paths:
             application/json:
               schema:
                 type: string
+  /useApplicationJsonContentType:
+    get:
+      tags:
+        - TypedResultNoProduces
+      responses:
+        '200':
+          description: '200'
+          content:
+            application/json:
+              schema:
+                type: string
 components:
   schemas:
     ProblemDetails:

src/tests/expected-openapi-document.yaml

@@ -407,6 +407,17 @@ paths:
             application/json:
               schema:
                 type: string
+  /useApplicationJsonContentType:
+    get:
+      tags:
+        - TypedResultNoProduces
+      responses:
+        '200':
+          description: '200'
+          content:
+            application/json:
+              schema:
+                type: string
 components:
   schemas:
     ProblemDetails: