4

I am attempting to use HttpClient in a .net core project to make a GET request to a REST service that accepts/returns JSON. I don't control the external service.

No matter how I try, I can't figure out to set the Content-Type header to application/json only.

When I use 

client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

it sends in the HTTP GET request:

Content-Type: application/json; charset=utf-8

However, this particular service does not work with this. It will only work if the header is:

Content-Type: application/json

I've tried setting headers without validation, and all the approaches I've found on the web/SO doesn't apply to .net core. All the other the approaches to sending HTTP requests aren't available in .net core, so I need to figure this out. How can I exclude the charset in content-type?

EDIT with workaround

As mentioned in the answers, the service should be using the Accept header. The workaround (as Shaun Luttin has in his answer) is to add an empty content to the GET (what? GETs don't have content! yeah...). It's not pretty, but it does work.

Erick T
  • 7,009
  • 9
  • 50
  • 85

2 Answers2

14

You're setting the Accept header. You need to set the ContentType header instead, which is only canonical for a POST.

var client = new HttpClient();
var content = new StringContent("myJson");
content.Headers.ContentType = MediaTypeHeaderValue.Parse("application/json");
var result = client.PostAsync("http://bigfont.ca", content).Result;

If you really want to set it for a GET, you can do this: 

var client = new HttpClient();
var message = new HttpRequestMessage(HttpMethod.Get, "http://www.bigfont.ca");
message.Content = new StringContent(string.Empty);
message.Content.Headers.Clear();
message.Content.Headers.Add("Content-Type", "application/json");
var result = client.SendAsync(message).Result;
Shaun Luttin
  • 133,272
  • 81
  • 405
  • 467
  • Any suggestions on how to do that? The HttpClient API doesn't seem to allow for the setting of Content-Type as a "generic" header – Erick T Oct 27 '16 at 01:10
  • Content-Type is part of a POST request not a GET. That is, a GET will not have a Content-Type header, since you are not posting any content. – Shaun Luttin Oct 27 '16 at 01:11
  • 1
    I appreciate that from a HTTP standpoint, but the service uses the content-type header in a get to determine which format to send back (json, xml, or msgpack). Should it use the Accept header? Probably, but it doesn't. – Erick T Oct 27 '16 at 01:13
  • 1
    Thanks Shaun, I think we both tried the same thing at the same time. :) – Erick T Oct 27 '16 at 01:30
0

If you are the client and you perform a GET request how can you specify the Content-Type? Isn't it supposed to say what your are able to Accept ? According to this 7.2.1 Type you can only set Content-Type when there is Body.

Searching
  • 2,269
  • 1
  • 17
  • 28
  • The problem is that service is not doing the right thing here. It is confusing the Accept and Content-Type (it uses Content-Type for both get and post. It is correct? No, but I still have to work with it. – Erick T Oct 27 '16 at 01:25
  • Aiyyeyaa...that's not good. Are you able to share the REST service? We'd like to try :) – Searching Oct 27 '16 at 01:27
  • Unfortunately not. Shaun and I found a workaround, but thanks for your help as well. – Erick T Oct 27 '16 at 01:31