Fix descriptions when using WithOpenApi (#3085)

Fixing breaking change when applying filters for WithOpenApi extension.

Author: jgarciadelanoceda

src/Swashbuckle.AspNetCore.SwaggerGen/SwaggerGenerator/SwaggerGenerator.cs

@@ -408,7 +408,7 @@ private async Task<OpenApiOperation> GenerateOpenApiOperationFromMetadataAsync(A
                 {
                     var (parameterAndContext, filterContext) = GenerateParameterAndContext(apiParameter, schemaRepository);
                     parameter.Schema = parameterAndContext.Schema;
-                    parameter.Description = parameterAndContext.Description;
+                    parameter.Description ??= parameterAndContext.Description;
 
                     foreach (var filter in _options.ParameterAsyncFilters)
                     {

test/Swashbuckle.AspNetCore.IntegrationTests/SwaggerVerifyIntegrationTest.SwaggerEndpoint_ReturnsValidSwaggerJson_For_WebApi_swaggerRequestUri=v1.verified.txt

@@ -246,6 +246,17 @@
         "tags": [
           "WithOpenApi"
         ],
+        "parameters": [
+          {
+            "name": "queryParameter",
+            "in": "query",
+            "description": "queryParameter Description",
+            "required": true,
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
         "requestBody": {
           "content": {
             "multipart/form-data": {

test/Swashbuckle.AspNetCore.IntegrationTests/SwaggerVerifyIntegrationTest.TypesAreRenderedCorrectly.verified.txt

@@ -246,6 +246,17 @@
         "tags": [
           "WithOpenApi"
         ],
+        "parameters": [
+          {
+            "name": "queryParameter",
+            "in": "query",
+            "description": "queryParameter Description",
+            "required": true,
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
         "requestBody": {
           "content": {
             "multipart/form-data": {

test/WebSites/Basic/Controllers/FilesController.cs

@@ -21,7 +21,7 @@ public IActionResult PostFiles(IFormFileCollection files)
         }
 
         [HttpPost("form-with-file")]
-        public IActionResult PostFormWithFile([FromForm]FormWithFile formWithFile)
+        public IActionResult PostFormWithFile([FromForm] FormWithFile formWithFile)
         {
             throw new NotImplementedException();
         }
@@ -41,7 +41,7 @@ public FileResult GetFile(string name)
             writer.Flush();
             stream.Position = 0;
 
-            var contentType = name.EndsWith(".zip", StringComparison.InvariantCultureIgnoreCase) ? "application/zip" : "text/plain";
+            var contentType = name.EndsWith(".zip", StringComparison.OrdinalIgnoreCase) ? "application/zip" : "text/plain";
 
             return File(stream, contentType, name);
         }

test/WebSites/WebApi/EndPoints/OpenApiEndpoints.cs

@@ -42,10 +42,18 @@ public static IEndpointRouteBuilder MapWithOpenApiEndpoints(this IEndpointRouteB
             })
             .WithOpenApi();
 
-            group.MapPost("/IFromFile", (IFormFile file) =>
+            group.MapPost("/IFromFile", (IFormFile file, string queryParameter) =>
             {
-                return file.FileName;
-            }).WithOpenApi();
+                return $"{file.FileName}{queryParameter}";
+            }).WithOpenApi(o =>
+            {
+                var parameter = o.Parameters.FirstOrDefault(p => p.Name.Equals("queryParameter", StringComparison.OrdinalIgnoreCase));
+                if (parameter is not null)
+                {
+                    parameter.Description = $"{parameter.Name} Description";
+                }
+                return o;
+            });
 
             group.MapPost("/IFromFileCollection", (IFormFileCollection collection) =>
             {