feat: Add example of multiple responses in swagger

Author: mt89vein

BookLibrary.Api/Features/Books/GetBook.cs

@@ -1,5 +1,7 @@
 using BookLibrary.Api.Extensions;
+using BookLibrary.Api.Swagger;
 using BookLibrary.Application.Features.Books.GetBook;
+using BookLibrary.Domain.Exceptions;
 using JetBrains.Annotations;
 using Microsoft.AspNetCore.Mvc;
 using Sstv.DomainExceptions.Extensions.ProblemDetails;
@@ -26,7 +28,8 @@ public sealed class GetBookController : ApiController
     /// <param name="useCase">UseCase - get book by id.</param>
     /// <param name="ct">Token for cancel operation.</param>
     [HttpGet]
-    [SwaggerResponse(StatusCodes.Status200OK, "Success", typeof(BookDto))]
+    [SwaggerErrorCodeResponse(ErrorCodes.BookNotFound)]
+    [SwaggerOkResponse<BookDto>]
     [SwaggerResponseExample(StatusCodes.Status200OK, typeof(BookDtoExample))]
     [SwaggerResponse(StatusCodes.Status400BadRequest, "In case bad request parameters", typeof(ErrorCodeProblemDetails))]
     [SwaggerResponse(StatusCodes.Status500InternalServerError, "In case server error", typeof(ErrorCodeProblemDetails))]

BookLibrary.Api/Swagger/MultipleProducesOperationFilter.cs

@@ -0,0 +1,47 @@
+using Microsoft.OpenApi.Models;
+using Swashbuckle.AspNetCore.Annotations;
+using Swashbuckle.AspNetCore.SwaggerGen;
+
+namespace BookLibrary.Api.Swagger;
+
+internal sealed class MultipleProducesOperationFilter : IOperationFilter
+{
+    public void Apply(OpenApiOperation operation, OperationFilterContext context)
+    {
+        var attrs = context.MethodInfo.GetCustomAttributes(false)
+            .OfType<SwaggerResponseAttribute>()
+            .GroupBy(attr => attr.StatusCode)
+            .Select(group => new { StatusCode = group.Key, Attributes = group.ToArray() })
+            .OrderBy(x => x.StatusCode)
+            .ToArray();
+
+        var duplicates = attrs
+            .Where(x => x.Attributes.Length > 1)
+            .ToArray();
+
+        if (duplicates.Length == 0)
+        {
+            return;
+        }
+
+        foreach (var details in duplicates)
+        {
+            var response = operation.Responses[details.StatusCode.ToString()];
+
+            foreach (var attr in details.Attributes)
+            {
+                if (attr is SwaggerErrorCodeResponse errorCodeResponse)
+                {
+                    var contentType = errorCodeResponse.ContentTypes.Single();
+                    if (!response.Content.TryGetValue(contentType, out var mediaType))
+                    {
+                        response.Content[contentType] = mediaType = new OpenApiMediaType();
+                    }
+
+                    mediaType.Schema = context.SchemaGenerator.GenerateSchema(attr.Type, context.SchemaRepository);
+                    mediaType.Example = errorCodeResponse.GetExample();
+                }
+            }
+        }
+    }
+}

BookLibrary.Api/Swagger/SwaggerConfigureOptions.cs

@@ -1,4 +1,4 @@
-using Microsoft.AspNetCore.Mvc.ApiExplorer;
+using Microsoft.AspNetCore.Mvc.ApiExplorer;
 using Microsoft.Extensions.Options;
 using Microsoft.OpenApi.Models;
 using Swashbuckle.AspNetCore.Filters;
@@ -48,6 +48,7 @@ public void Configure(SwaggerGenOptions options)
         options.ExampleFilters();
         options.AddServer(new OpenApiServer { Description = "BookLibrary API", Url = pathBase });
 
+        options.OperationFilter<MultipleProducesOperationFilter>();
         options.AddEnumsWithValuesFixFilters(o =>
         {
             o.DescriptionSource = DescriptionSources.DescriptionAttributesThenXmlComments;

BookLibrary.Api/Swagger/SwaggerErrorCodeResponse.cs

@@ -0,0 +1,41 @@
+using BookLibrary.Api.ProblemDetails;
+using BookLibrary.Domain.Exceptions;
+using Microsoft.OpenApi.Any;
+using Sstv.DomainExceptions.Extensions.ProblemDetails;
+using Swashbuckle.AspNetCore.Annotations;
+using System.Net.Mime;
+
+namespace BookLibrary.Api.Swagger;
+
+/// <summary>
+/// Error code response.
+/// </summary>
+public sealed class SwaggerErrorCodeResponse : SwaggerResponseAttribute
+{
+    public ErrorCodes ErrorCode { get; }
+
+    public SwaggerErrorCodeResponse(ErrorCodes errorCode, string? description = null)
+        : base(
+            ErrorCodeMapping.MapToStatusCode(errorCode.GetDescription()),
+            description,
+            typeof(ErrorCodeProblemDetails),
+            contentTypes: [MediaTypeNames.Application.ProblemJson]
+        )
+    {
+        ErrorCode = errorCode;
+    }
+
+    public IOpenApiAny GetExample()
+    {
+        var error = ErrorCode.GetDescription();
+
+        return new OpenApiObject
+        {
+            ["code"] = new OpenApiString(error.ErrorCode),
+            ["type"] = new OpenApiString(error.HelpLink),
+            ["title"] = new OpenApiString(error.Description),
+            ["status"] = new OpenApiInteger(StatusCode),
+            ["criticalityLevel"] = new OpenApiString(Enum.GetName(error.Level))
+        };
+    }
+}

BookLibrary.Api/Swagger/SwaggerOkResponse.cs

@@ -0,0 +1,12 @@
+using Swashbuckle.AspNetCore.Annotations;
+using System.Net.Mime;
+
+namespace BookLibrary.Api.Swagger;
+
+public sealed class SwaggerOkResponse<T> : SwaggerResponseAttribute
+{
+    public SwaggerOkResponse(string? description = null)
+        : base(StatusCodes.Status200OK, description, typeof(T), MediaTypeNames.Application.Json)
+    {
+    }
+}