将内容类型标头添加到 httpclient GET 请求

Question

I am trying to add Content-Type header to HttpClient GET request, here my code:

HttpClient client=new ....
bool added = client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/x-www-form-urlencoded");
var response = await client.GetAsync(...

but the added variable is false, ie it failed to add the header.

How can I add this header?

NOTE:

This post deals with POST request, I asked about GET

Answer 1

If you look at the Http/1.1 specification :

A sender that generates a message containing a payload body SHOULD generate a Content-Type header field in that message unless the intended media type of the enclosed representation is unknown to the sender. If a Content-Type header field is not present, the recipient MAY either assume a media type of "application/octet-stream" ([RFC2046], Section 4.5.1) or examine the data to determine its type.

Check also the MDN on get requests

The HTTP GET method requests a representation of the specified resource. Requests using GET should only retrieve data.

Sending body/payload in a GET request may cause some existing implementations to reject the request — while not prohibited by the specification, the semantics are undefined. It is better to just avoid sending payloads in GET requests.

Effectively, that means that wether you send or not the header, it's going to be ignored and/or rejected.

When setting the content type, it's better to set it from the content itself: How do you set the Content-Type header for an HttpClient request?

Answer 2

Im currently working on a project, where I call an api using a POST request. This might help in your case. Its how its done in an official Microsoft Documentation.

using (var content = new ByteArrayContent(byteData))
{
// This example uses the "application/octet-stream" content type.
// The other content types you can use are "application/json"
// and "multipart/form-data".
content.Headers.ContentType = new mediaTypeHeaderValue("application/octet-stream");
response = await client.PostAsync(uriBase, content);
}