Validating Request Content-Type

Alexandre Vicenzi Published at Dev

Alexandre Vicenzi

I'm trying to validate the value of Content-Type in POST, PUT and PATCH requests, but the current code is only working when I forget the content-type clause or when I use a content-type like: "Content-Type: Foo".
When I send "Content-Type: text/css" I get this:

500 Internal Server Error
No MediaTypeFormatter is available to read an object of type 'MyClassDto' from content with media type 'text/css'.

This is my code:

public class ContentTypeFilter : IActionFilter
{
    private readonly List<MediaTypeHeaderValue> _suport;

    /// <summary />
    public ContentTypeFilterAttribute()
    {
        _suport = new List<MediaTypeHeaderValue>();

        foreach (var formatter in GlobalConfiguration.Configuration.Formatters.ToArray())
        {
            _suport.AddRange(formatter.SupportedMediaTypes);
        }
    }

    public bool AllowMultiple { get { return false; } }

    public Task<HttpResponseMessage> ExecuteActionFilterAsync(HttpActionContext actionContext, CancellationToken cancellationToken, Func<Task<HttpResponseMessage>> continuation)
    {
        var metodos = new List<string> { "POST", "PUT", "PATCH" };

        if (actionContext.Request.Content != null)
        {
            if (metodos.Contains(actionContext.Request.Method.Method.ToUpperInvariant()))
            {
                MediaTypeHeaderValue contentType = actionContext.Request.Content.Headers.ContentType;

                if (contentType == null || !_suport.Any(x => x.MediaType.Equals(contentType.MediaType)))
                {
                    return CreateResponse(actionContext.Request, "Invalid Content-Type");
                }
            }
        }

        return continuation();
    }

    private static Task<HttpResponseMessage> CreateResponse(HttpRequestMessage request, string mensagem)
    {
        var tsc = new TaskCompletionSource<HttpResponseMessage>();
        var response = request.CreateResponse(HttpStatusCode.UnsupportedMediaType);
        response.ReasonPhrase = mensagem;
        response.Content = new StringContent(mensagem);
        tsc.SetResult(response);

        return tsc.Task;
    }

Is there another way to validate content-type and return error 415 if the content isn't XML or JSON?

Alexandre Vicenzi

I've found a good solution here.

With some changes to get what I want:

public class ContentTypeFilter : DelegatingHandler
{
    private readonly List<MediaTypeHeaderValue> _suport;

    /// <summary />
    public ContentTypeFilter()
    {
        _suport = new List<MediaTypeHeaderValue>();

        foreach (var formatter in GlobalConfiguration.Configuration.Formatters.ToArray())
        {
            _suport.AddRange(formatter.SupportedMediaTypes);
        }
    }

    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var metodos = new List<string> { "POST", "PUT", "PATCH" };

        if (request.Content != null)
        {
            if (metodos.Contains(request.Method.Method.ToUpperInvariant()))
            {
                MediaTypeHeaderValue contentType = request.Content.Headers.ContentType;

                // Nas configurações não possui o Charset aceito.
                if (contentType == null || !_suport.Any(x => x.MediaType.Equals(contentType.MediaType)))
                {
                    return Task<HttpResponseMessage>.Factory.StartNew(() => CreateResponse(request, "Suported content-types: " + string.Join(", ", _suport.Select(x => x.ToString()))));
                }
            }
        }
        return base.SendAsync(request, cancellationToken);
    }

    private static HttpResponseMessage CreateResponse(HttpRequestMessage request, string mensagem)
    {
        var response = request.CreateResponse(HttpStatusCode.UnsupportedMediaType);
        response.ReasonPhrase = mensagem;
        response.Content = new StringContent(mensagem);

        return response;
    }
}

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