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Getting web API path from swagger

I have swagger URL http://somehost/swagger/index.html
end methods there as shown on image:
As someone said to me http://somehost/api/Referral/GetReferralByNumber is API address which I can refer it by HTTP request.
static void Main(string[] args)
{
try
{
System.Net.WebClient client = new System.Net.WebClient();
string result = client.DownloadString("http://somehost/api/Referral/GetReferralByNumber");
}
catch (System.Net.WebException ex)
{
Console.WriteLine(ex);
}
Console.ReadKey();
}
this is code for testing API, but
System.Net.WebException: The remote server returned an error: (404)
Not Found exception
is thrown. any help?

Client.DownloadString() makes an GET request. Your action supports POST. Try to use HttpClient, it should be better for your case.

You are hitting a Get Request and for Get request there is no such endpoint.
You should try adding the HTTP option Post to the server.
Code:
private static readonly HttpClient client = new HttpClient();
HttpResponseMessage response = await client.PostAsJsonAsync(
"api/referral/GetReferralByNumber", data);
Where data is the data which should be posted to the server.

You should create an http client and use POST like this:
var method = HttpMethod.Post;
var endPoint = "http://somehost/api/Referral/GetReferralByNumber";
var request = new HttpRequestMessage(method, endPoint);
var client = new HttpClient();
var response = await httpClient.SendAsync(request);

A HttpRequest Redirect Exception in UWP Project

The code goes below
public static async Task<string> getForwardUrl(string url)
{
try
{
HttpClient client = new HttpClient();
HttpRequestMessage forwardRequest = new HttpRequestMessage();
forwardRequest.RequestUri = new Uri(url);
HttpResponseMessage Message = await client.SendAsync(forwardRequest);
return Message.RequestMessage.RequestUri.OriginalString;
}
catch (Exception ex)
{
WriteLine(ex.Message);
}
//...
}
When I run this in a uwp project, exception occurs. The message of this exception shows that the redirection request would change the safe connection to an unsafe one(After that , I checked the URL of the login page , It's https ,but the page after I logged in is http).
I find a similar question, he recommends using Windows.Web.Http instead of System.Net.Http but I get the same error message.
Thanks for your reply
EDIT:
The URL is: https://tinyurl.com /57muy (remove the space) or short a http url with tinyurl.com! The problem only occurs with a shortet http side!
Error: An error occurred while sending the request. Innermessage: Error message not found for this error

According to your description, I'd suppose you are developing a UWP app. And as you've mentioned, we got the exception here because the redirection request would change the safe connection to an unsafe one. To solve this problem, we can turn off auto-redirect and do the redirection by ourselves.
For example:
public static async Task<string> getForwardUrl(string url)
{
var handler = new System.Net.Http.HttpClientHandler();
handler.AllowAutoRedirect = false;
var client = new System.Net.Http.HttpClient(handler);
var response = await client.GetAsync(url);
if (response.StatusCode == System.Net.HttpStatusCode.Redirect || response.StatusCode == System.Net.HttpStatusCode.Moved)
{
return response.Headers.Location.AbsoluteUri;
}
return url;
}

HTTPWebRequest GET request causing SSL connection issue

I am trying to connect to a RESTful API and when I access the URL from my browser I get an error stating I am missing headers which is what I was expecting to get. When I connect to the same URL using the below code I get an error stating "The underlying connection was closed: An unexpected error occurred on a send. ---> System.IO.IOException: Authentication failed because the remote party has closed the transport stream". If I use the same code and change the URL to Google.com it works fine and to add to the mystery the connection I make to the API URL from my browser will generate an entry in the Apache logs on the API server, but the below code doesn't. Does anyone have any ideas why I would get that error?
var httpWebRequest = (HttpWebRequest)WebRequest.Create("HTTPS://URL.COM");
httpWebRequest.ContentType = "application/json";
httpWebRequest.Method = "GET";
string html = string.Empty;
try
{
HttpWebResponse response = (HttpWebResponse)httpWebRequest.GetResponse();
string responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
Response.Write(responseString);
}
catch (Exception ex)
{
Response.Write(ex.ToString());
}
UPDATE: I tried using HttpClient and got the same results:
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("https://url.com/");
// Add an Accept header for JSON format.
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = client.GetAsync("v1/person").Result;
if (response.IsSuccessStatusCode)
{
Response.Write(response);
}
else
{
Response.Write(response);
}
UPDATE 2: The below line of code seems to fix the problem. I am awaiting confirmation now. I am still a little baffled why this was required though.
System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;

Does a web file exist - using same function to get the Content Type

I have a function that is coded to get the Content-Type of a web file.
Here is the function:
public string GetContentTypeOfUri(string uri)
{
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.Method = "HEAD";
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
var contentType = response.Headers["Content-Type"];
return (contentType);
}
}
catch (Exception ex)
{
return "error";
}
}
Rather than writing a whole different function to detect if a web file exists, how can I calculate if a file exists from the same code as used to get the Content-Type?
If I use a uri of a file that does not exist, an exception occurs. The ex.HResult equals -2146233079 when this exception occurs, with a message = "The remote name could not be resolved: '[address name]'".
Is it safe to say that when an exception occurs, and the ex.HResult equals -2146233079, the file does not exist?
Is there an easier/better way to work this out?
Thanks in advance
EDIT
Here is the HttpClient code that I have:
public async Task<string> GetContentTypeAsync(string uri)
{
using (var httpClient = new HttpClient())
{
var request = new HttpRequestMessage(HttpMethod.Post, uri);
request.Method = new HttpMethod("HEAD");
var response = await httpClient.SendAsync(request);
string contentType = response.Content.Headers.ContentType.ToString();
return contentType;
}
}
Your example web address does inform me that the address does not exist, however, if I have a web address that does not exist such as http://www.usa.canon.com/app/html/HDV/HG10/images/hg10_sample_image_03.jpg5, I am getting a StatusCode of OK, as a Text content type is returned as a custom error page.

There are two possible "not exists" scenarios. It sounds like you've identified one of them - when the server name in the URL is incorrect and so the request cannot even be sent.
But you're not accounting for the other error - that you can reach a remote server but it denies all knowledge of a specific file. For that scenario, you ought to be checking for status 404 on the response.
For cleaner handling of your current scenario (server doesn't exist) you could use the Uri class to extract the Host name from the uri string and perform a manual DNS lookup - which would allow you to code for this likely scenario without having to catch exceptions - which is generally frowned upon when its an expected scenario.

C# WebRequest Check if page requires HTTP Authentication

Does anyone know how to check if a webpage is asking for HTTP Authentication via C# using the WebRequest class? I'm not asking how to post Credentials to the page, just how to check if the page is asking for Authentication.
Current Snippet to get HTML:
WebRequest wrq = WebRequest.Create(address);
wrs = wrq.GetResponse();
Uri uri = wrs.ResponseUri;
StreamReader strdr = new StreamReader(wrs.GetResponseStream());
string html = strdr.ReadToEnd();
wrs.Close();
strdr.Close();
return html;
PHP Server side source:
<?php
if (!isset($_SERVER['PHP_AUTH_USER'])) {
header('WWW-Authenticate: Basic realm="Secure Sign-in"');
header('HTTP/1.0 401 Unauthorized');
echo 'Text to send if user hits Cancel button';
exit;
} else {
echo "<p>Hello {$_SERVER['PHP_AUTH_USER']}.</p>";
echo "<p>You entered {$_SERVER['PHP_AUTH_PW']} as your password.</p>";
}
?>

WebRequest.GetResponse returns an object of type HttpWebResponse. Just cast it and you can retrieve StatusCode.
However, .Net will give you an exception if it receives a response of status 4xx or 5xx (thanks for your feedback).
There is a little workaround, check it out:
HttpWebRequest wrq = (HttpWebRequest)WebRequest.Create(#"http://webstrand.comoj.com/locked/safe.php");
HttpWebResponse wrs = null;
try
{
wrs = (HttpWebResponse)wrq.GetResponse();
}
catch (System.Net.WebException protocolError)
{
if (((HttpWebResponse)protocolError.Response).StatusCode == HttpStatusCode.Unauthorized)
{
//do something
}
}
catch (System.Exception generalError)
{
//run to the hills
}
if (wrs.StatusCode == HttpStatusCode.OK)
{
Uri uri = wrs.ResponseUri;
StreamReader strdr = new StreamReader(wrs.GetResponseStream());
string html = strdr.ReadToEnd();
wrs.Close();
strdr.Close();
}
Hope this helps.
Regards

Might want to try
WebClient wc = new WebClient();
CredentialCache credCache = new CredentialCache();
If you can work with WebClient instead of WebRequest, you should it's a bit higher level, easier to handle headers etc.
Also, might want to check this thread:
System.Net.WebClient fails weirdly