C# How to set Custom request headers using HttpClient in GET Method?

Question

i am using HttpClient to send request, i want to use my custom request headers using HttpClient in GET Method?

Here is my code:

public HttpResponseMessage Get(string url, List<KeyValuePair<string, string>> headers = null)
    {
        HttpRequestMessage request = new HttpRequestMessage()
        {
            RequestUri = new Uri(url),
            Method = HttpMethod.Get,
        };
        if (headers != null && headers.Count > 0)
        {
            foreach (var header in headers)
            {                    
                request.Headers.Add(header.Key, header.Value);

            }
        }            
        HttpResponseMessage response = httpClient.SendAsync(request).Result;
        return response;
    }

But it threw an error at request.Headers.Add(header.Key, header.Value);

Below is the error message:

Misused header name. Make sure request headers are used with HttpRequestMessage, response headers with HttpResponseMessage, and content headers with HttpContent objects.

Any help would be appreciated

Did you debug the code? What values you have in `header.Key` and `header.Value` when you get the exception? — Chetan, Jan 24 '19 at 09:20
My header is "Content-Type" "application/json". I found the workaround at https://stackoverflow.com/questions/10679214/how-do-you-set-the-content-type-header-for-an-httpclient-request, but it is only suitable for Http Post method — Lee Liu, Jan 24 '19 at 09:23
For GET request setting Content-Type header is not valid. You simply can not set Content-Type header for GET requests. You should not. — Chetan, Jan 24 '19 at 09:28
@LeeLiu that's not a workaround, that's the answer. GET has no content so using `Content-Type` is a bug. If you want to request a specific content type use the `Accept` header — Panagiotis Kanavos, Jan 24 '19 at 09:29
@ChetanRanpariya If i want to set my customer header like "domain:005", how can i do that? — Lee Liu, Jan 24 '19 at 09:30
@PanagiotisKanavos if i want to use my custom request headers like "domain" "005", how can i achieve it? — Lee Liu, Jan 24 '19 at 09:31
@LeeLiu you already do it. The problem is that you used an invalid header — Panagiotis Kanavos, Jan 24 '19 at 09:33
@PanagiotisKanavos as you said above, it is not a workaround, why do you set my this thread to be duplicate — Lee Liu, Jan 24 '19 at 09:33
Then you should not have Content-Type in the `headers` collection? Or you can check for the header name in foreach loop and do not add it to request. — Chetan, Jan 24 '19 at 09:34
@LeeLiu because it is. You don't need a workaround, you tried to use an invalid header name and the answers to the duplicates explain this. They show how to set request and content headers using the correct objects — Panagiotis Kanavos, Jan 24 '19 at 09:34
@PanagiotisKanavos I need to use customer headers via httpclient,i can do that with Post method, but failed with Get Method. — Lee Liu, Jan 24 '19 at 09:34
@LeeLiu you already wrote that multiple times. Repeating it won't change the fact that a) you *can*, with the very code you used and b) you can't use *invalid* names. Post a *specific example* - which header did you try to set, using which value and which error did you get. Please don't say `content-type`, as everyone in the comments explained, that's *invalid* for GET requests — Panagiotis Kanavos, Jan 24 '19 at 09:36
@LeeLiu the second duplicate shows how to set headers. The code isn't really different from you code but it shows how to set the `Accept` header for a GET request — Panagiotis Kanavos, Jan 24 '19 at 09:38
@PanagiotisKanavos Thank you for your patience, i have find the solution, we can use "request.Headers.TryAddWithoutValidation(header.Key, header.Value);" to achieve it. — Lee Liu, Jan 24 '19 at 09:48
@LeeLiu that's no solution, that's covering up the problem. Why do you insist on using an *invalid* header? — Panagiotis Kanavos, Jan 24 '19 at 09:49
@PanagiotisKanavos Beacuse i have the requirement that it needs to set arguments in request headers, for example: "user_Token : xxxxxxx", not only the "Content-Type" — Lee Liu, Jan 24 '19 at 09:52
@PanagiotisKanavos I used WebClient before, it has no problem, but with HttpClient, it failed. it's so terrible. — Lee Liu, Jan 24 '19 at 09:53
@LeeLiu then you can use the code you already posted. Post an example that demonstrates your actual problem. You should be able to use `user_Token`. You aren't supposed to use `content-type` — Panagiotis Kanavos, Jan 24 '19 at 09:53
@LeeLiu that's why WebClient is obsolete for the past 7 years, it allowed a lot of buggy calls. — Panagiotis Kanavos, Jan 24 '19 at 09:54
@PanagiotisKanavos it's my fault that didn't explain clearly,thank you again — Lee Liu, Jan 24 '19 at 09:58

score 2 · Accepted Answer · answered Jan 24 '19 at 09:23

2

You should do this with using your HttpClient instance like below:

httpClient.DefaultRequestHeaders
      .Accept
      .Add(new MediaTypeWithQualityHeaderValue("x-your-custom-header"));

answered Jan 24 '19 at 09:23

Saman Gholami

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C# How to set Custom request headers using HttpClient in GET Method?

1 Answers1