Add OpenAPI extension methods to resolve #33924

Author: captainsafia

src/Mvc/Mvc.Core/src/Builder/OpenApiEndpointConventionBuilderExtensions.cs

@@ -0,0 +1,81 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Builder;
+
+namespace Microsoft.AspNetCore.Http
+{
+    /// <summary>
+    /// Extension methods for adding response type metadata to endpoints.
+    /// </summary>
+    public static class OpenApiEndpointConventionBuilderExtensions
+    {
+        /// <summary>
+        /// Adds metadata indicating the type of response an endpoint produces.
+        /// </summary>
+        /// <typeparam name="TResponse">The type of the response.</typeparam>
+        /// <param name="builder">The <see cref="IEndpointConventionBuilder"/>.</param>
+        /// <param name="statusCode">The response status code. Defatuls to StatusCodes.Status200OK.</param>
+        /// <param name="contentType">The response content type. Defaults to "application/json"</param>
+        /// <param name="additionalContentTypes">Additional response content types the endpoint produces for the supplied status code.</param>
+        /// <returns>A <see cref="IEndpointConventionBuilder"/> that can be used to further customize the endpoint.</returns>
+        public static IEndpointConventionBuilder Produces<TResponse>(this IEndpointConventionBuilder builder,
+            int statusCode = StatusCodes.Status200OK,
+            string? contentType = "application/json",
+            params string[] additionalContentTypes)
+        {
+            return Produces(builder, statusCode, typeof(TResponse), contentType, additionalContentTypes);
+        }
+
+        /// <summary>
+        /// Adds metadata indicating the type of response an endpoint produces.
+        /// </summary>
+        /// <param name="builder">The <see cref="IEndpointConventionBuilder"/>.</param>
+        /// <param name="statusCode">The response status code. Defatuls to StatusCodes.Status200OK.</param>
+        /// <param name="responseType">The type of the response. Defaults to null.</param>
+        /// <param name="contentType">The response content type. Defaults to "application/json" if responseType is not null, otherwise defaults to null.</param>
+        /// <param name="additionalContentTypes">Additional response content types the endpoint produces for the supplied status code.</param>
+        /// <returns>A <see cref="IEndpointConventionBuilder"/> that can be used to further customize the endpoint.</returns>
+        public static IEndpointConventionBuilder Produces(this IEndpointConventionBuilder builder,
+            int statusCode = StatusCodes.Status200OK,
+            Type? responseType = null,
+            string? contentType = null,
+            params string[] additionalContentTypes)
+        {
+            if (responseType is Type && string.IsNullOrEmpty(contentType))
+            {
+                contentType = "application/json";
+            }
+
+            builder.WithMetadata(new ProducesResponseTypeAttribute(responseType ?? typeof(void), statusCode, contentType, additionalContentTypes));
+
+            return builder;
+        }
+
+        /// <summary>
+        /// Adds metadata indicating that the endpoint produces a Problem Details response.
+        /// </summary>
+        /// <param name="builder">The <see cref="IEndpointConventionBuilder"/>.</param>
+        /// <param name="statusCode">The response status code. Defatuls to StatusCodes.Status500InternalServerError.</param>
+        /// <param name="contentType">The response content type. Defaults to "application/problem+json".</param>
+        /// <returns>A <see cref="IEndpointConventionBuilder"/> that can be used to further customize the endpoint.</returns>
+        public static IEndpointConventionBuilder ProducesProblem(this IEndpointConventionBuilder builder,
+            int statusCode = StatusCodes.Status500InternalServerError,
+            string contentType = "application/problem+json")
+        {
+            return Produces<ProblemDetails>(builder, statusCode, contentType);
+        }
+
+        /// <summary>
+        /// Adds metadata indicating that the endpoint produces a ProblemDetails response for validation errors.
+        /// </summary>
+        /// <param name="builder">The <see cref="IEndpointConventionBuilder"/>.</param>
+        /// <param name="statusCode">The response status code. Defatuls to StatusCodes.Status400BadRequest.</param>
+        /// <param name="contentType">The response content type. Defaults to "application/problem+json".</param>
+        /// <returns>A <see cref="IEndpointConventionBuilder"/> that can be used to further customize the endpoint.</returns>
+        public static IEndpointConventionBuilder ProducesValidationProblem(this IEndpointConventionBuilder builder,
+            int statusCode = StatusCodes.Status400BadRequest,
+            string contentType = "application/problem+json")
+        {
+            return Produces<HttpValidationProblemDetails>(builder, statusCode, contentType);
+        }
+    }
+}