how to add 'Content-Type' header in (HTTP GET) Rest request header collection using HttpClient? - vb.net

Question

I am using HttpClient for rest service . At at one point I have a problem when I try to add "Content-Type" in my 'Get' request header .
I know "Content-Type" is suitable for content send in request body part But It's my need i have to send "Content-Type" with request header part.
I also try to remove "Content-Type" header from Invalid Header list of HttpRequestHeaders
I find link How do you set the Content-Type header for an HttpClient request?
Dim field = GetType(System.Net.Http.Headers.HttpRequestHeaders).GetField("invalidHeaders", System.Reflection.BindingFlags.NonPublic Or System.Reflection.BindingFlags.[Static])
If field IsNot Nothing Then
Dim invalidFields = DirectCast(field.GetValue(Nothing), HashSet(Of String))
invalidFields.Remove("Content-Type")
End If
But my issue not resolved I have exception
InnerException:
Message=The 'content-type' header must be modified using the appropriate property or method.
StackTrace:
at System.Net.WebHeaderCollection.ThrowOnRestrictedHeader(String headerName)
at System.Net.WebHeaderCollection.Add(String name, String value)
at System.Net.Http.HttpClientHandler.SetRequestHeaders(HttpWebRequest webRequest, HttpRequestMessage request)
at System.Net.Http.HttpClientHandler.CreateAndPrepareWebRequest(HttpRequestMessage request)
at System.Net.Http.HttpClientHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
InnerException:
I find some tools like Postman or SoupUI allow this .
Please help me to find some solution .
Thanks

Answer 1

HttpWebRequest may come to your rescue.
private static string CallService(string url)
{
WebRequest req = WebRequest.Create(url);
req.Method = "GET";
String json;
req.ContentType = "application/json; charset=utf-8";
var resp = req.GetResponse();
using (varstream = resp.GetResponseStream())
{
var re = new StreamReader(stream);
json = re.ReadToEnd();
}
return json;
}
}
Async implementation of this can be found from Getting the Response of a Asynchronous HttpWebRequest