How to read header data from a web API response in .NET Core?

Question

I am calling the web API methods from my client project and returning the value from response header to client:

[HttpPost]
[AllowAnonymous]
[Route("login")]
public IActionResult Login(Users user)
{
    string s = _repository.Users.ValidateUser(user);
    if (s == "success")
    {
        Users u = _repository.Users.FindByUserName(user.UserName);
        int pid = u.PersonId;
        string role = "";
        if (u != null)
        {

            role = _repository.RoleManager.GetRole(u.Id);
        }
        Response.Headers.Add("Role", role);
        return Ok(pid.ToString());
    }

}

And I tried the code below for getting header value in the client application:

[HttpPost]
public IActionResult Login(Users user)
{    
    string pid = "";
    HttpClient client = service.GetService();
    HttpResponseMessage response = client.PostAsJsonAsync("api/mymethod", user).Result;
    Task<string> tokenResult = response.Content.ReadAsAsync<string>();
    pid = tokenResult.Result.ToString();
       
    var headers = response.Headers;
    string role = "";
    if (headers.TryGetValues("Role", out IEnumerable<string> headerValues))
        {
            role = headerValues.ToString();
        }

    return RedirectToAction("Profile");
}

But it returns System.String[] .

Please show me the right way for fetching data from the response header.

Possible duplicate of [How to extract custom header value?](https://stackoverflow.com/questions/38794749/how-to-extract-custom-header-value) — Chris.ZA, Dec 08 '18 at 03:49
Thanks for reply...it shows reading data from request but I want to read data from response header — Tejas, Dec 08 '18 at 04:02
Can you add the code of the getRole-method? I think it’s the source of confusion — Nikolaus, Dec 08 '18 at 04:12

score 7 · Accepted Answer · edited Nov 09 '21 at 23:45

7

I found the solution:

var headers = response.Headers;
string role = "";
if (headers.TryGetValues("Role", out IEnumerable<string> headerValues))
{
    role = headerValues.FirstOrDefault();
}

Don't forget to add a reference to System.Linq.

edited Nov 09 '21 at 23:45

Merna Mustafa

1,235
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answered Dec 08 '18 at 06:32

Tejas

381
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7
25

score 1 · Answer 2 · edited Nov 09 '21 at 17:37

1

Using StringValues:

var headers = response.Headers;
string role = "";
if (headers.TryGetValues("Role", out Microsoft.Extensions.Primitives.StringValues headerValues))
{
    role = headerValues.FirstOrDefault();
}

edited Nov 09 '21 at 17:37

janw

8,758
11
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answered Nov 03 '21 at 06:37

Idris

351
1
9

I don't know why in my code there is no `headers.TryGetValues` but `headers.TryGetValue` with no 's' – Nurkartiko Mar 26 '22 at 05:07

How to read header data from a web API response in .NET Core?

2 Answers2