创建自定义 model 活页夹并从查询中使用时获取不受支持的媒体类型

Question

in asp.net core 3.1 i create custom model binder,and it's work fine. in controller when i use FromQuery with complex model i get Unsupported Media Type.

controller and class:

    public class myModel
    {
        public myModel()
        {}
        public int ProjectId { get; set; }
        public int OwnerId { get; set; }
    }


[HttpGet("project/list/GetData")]
public async Task<IActionResult> GetData([FromQuery]myModel model)
        {
          //some code
        }

startup code:

    services.AddMvc().AddMvcOptions(options =>
                {
                    options.AllowEmptyInputInBodyModelBinding = true;


                    IHttpRequestStreamReaderFactory readerFactory = services.BuildServiceProvider().GetRequiredService<IHttpRequestStreamReaderFactory>();
                    options.ModelBinderProviders.Insert(0, new DefaultsModelBinderProvider(options.InputFormatters, readerFactory));
                });

my BinderProvider class:

     public class DefaultsModelBinderProvider : IModelBinderProvider
        {
            private readonly IList<IInputFormatter> formatters;
            private readonly IHttpRequestStreamReaderFactory readerFactory;

            public DefaultsModelBinderProvider(IList<IInputFormatter> formatters, IHttpRequestStreamReaderFactory readerFactory)
            {
                this.formatters = formatters;
                this.readerFactory = readerFactory;
            }
            public IModelBinder GetBinder(ModelBinderProviderContext context)
            {

                if (context.Metadata.ModelType.BaseType.IsAssignableFrom(typeof(MyRequest)))
                    return new DefaultsModelBinder(formatters, readerFactory);

                return null;
            }

and ModelBinder:

        public class DefaultsModelBinder : IModelBinder
        {
            private BodyModelBinder defaultBinder;

            public DefaultsModelBinder(IList<IInputFormatter> formatters, IHttpRequestStreamReaderFactory readerFactory)
            {
                defaultBinder = new BodyModelBinder(formatters, readerFactory);
            }

            public async Task BindModelAsync(ModelBindingContext bindingContext)
            {
                await defaultBinder.BindModelAsync(bindingContext);
                if (!bindingContext.Result.IsModelSet) return; //<= problem is here,and IsModelSet was false

            //some code
            }

        }

my response:

{
    "type": "https://tools.ietf.org/html/rfc7231#section-6.5.13",
    "title": "Unsupported Media Type",
    "status": 415,
    "traceId": "|a8d35c74-47e9398b95bd3d9f." 
}

I couldn't find the problem What do you think is the problem and what should I do to solve this problem? thank's for your help

Answer 1

A 415 here means simply that the mime type of the request body doesn't have any applicable formatter in ASP.NET Core. For example, out of the box, you get this if you send XML as the XML formatters are not included by default. If you add them in, then the error goes away, because ASP.NET Core then knows how to handle the application/xml mimetype, namely via sending it over to an XML serializer to deserialize it into an object.

None of that is applicable to anything coming FromQuery . The query string doesn't have a mime type: it's just key-value pairs of strings. It's not clear how you're making the request or what the request actually looks like from the question, but to get this error, you're sending something in the body, and that something is off.