Develop Reference

Refactor HttpWebRequest to HttpClient?

How would I convert this to HttpClient? What I'm looking to do is submit a Tweet to the Twitter api and get the response as Json. The HttpWebRequest is working fine but I just want to port it to HttpClient. I made an attempt at it in the second code example, but it's not actually sending or receiving the response.
HttpWebRequest request = null;
WebResponse response = null;
string responseCode = String.Empty;
try
{
string postBody = "status=" + EncodingUtils.UrlEncode(status);
request = (HttpWebRequest)HttpWebRequest.Create(resource_url);
request.ServicePoint.Expect100Continue = true;
request.UseDefaultCredentials = true;
request.PreAuthenticate = true;
request.Credentials = CredentialCache.DefaultCredentials;
request.ServicePoint.ConnectionLimit = 1;
request.Headers.Add("Authorization", authHeader);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
using (Stream stream = request.GetRequestStream())
{
using (StreamWriter writer = new StreamWriter(stream))
{
writer.Write(postBody);
}
}
using (response = request.GetResponse())
{
response.ContentType = "application/json";
responseCode = ((HttpWebResponse)response).StatusCode.ToString();
}
}
catch (WebException ex)
{
if (ex.Status != WebExceptionStatus.NameResolutionFailure)
{
request.Abort();
request = null;
}
throw ex;
}
return responseCode;
This is what I've tried to get it work:
private async Task<string> MakeWebRequest1(string status, string resource_url, string authHeader)
{
HttpClientHandler clientHandler = new HttpClientHandler();
clientHandler.Credentials = CredentialCache.DefaultCredentials;
clientHandler.PreAuthenticate = true;
clientHandler.AllowAutoRedirect = true;
string responseCode = "";
string postBody = "status=" + EncodingUtils.UrlEncode(status);
var request = new HttpRequestMessage()
{
RequestUri = new Uri(resource_url),
Method = HttpMethod.Post,
};
request.Headers.Add("Authorization", authHeader);
// request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");
request.Content = new StringContent(postBody, Encoding.UTF8,"application/x-www-form-urlencoded");//CONTENT-TYPE header
using (HttpClient client = new HttpClient(clientHandler))
{
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/x-www-form-urlencoded"));
// Stream stuff = await client.GetStreamAsync(resource_url);
using (HttpResponseMessage response = await client.SendAsync(request))
{
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
if(response.StatusCode == HttpStatusCode.OK)
{
responseCode = "OK";
}
}
}
clientHandler.Dispose();
return responseCode;
}
enter code here
I've tried to add another parameter to the request and it's always coming back as 401 unauthorized. I'm trying to create a Twitter thread. If I remove the in_reply_to_status_id then it's fine.
data = new Dictionary<string, string> {
["status"] = "#username + status,
["in_reply_to_status_id"] = "1167588690929115136"
};
The Twitter API describes it here https://developer.twitter.com/en/docs/tweets/post-and-engage/api-reference/post-statuses-update

Reference You're using HttpClient wrong to understand why a static client is being used.
static Lazy<HttpClient> client = new Lazy<HttpClient>(() => {
HttpClientHandler clientHandler = new HttpClientHandler {
Credentials = CredentialCache.DefaultCredentials,
PreAuthenticate = true,
AllowAutoRedirect = true
};
return new HttpClient(clientHandler);
});
private async Task<string> PostStatusRequestAsync(string status, string resource_url, string authHeader) {
using (var request = new HttpRequestMessage(HttpMethod.Post, resource_url)) {
request.Headers.TryAddWithoutValidation("Authorization", authHeader);
request.Headers.Accept.Clear();
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var data = new Dictionary<string, string> {
["status"] = status
};
request.Content = new FormUrlEncodedContent(data);
using (HttpResponseMessage response = await client.Value.SendAsync(request)) {
return response.StatusCode.ToString();
}
}
}
Note the use of the FormUrlEncodedContent for the request body, which will encode and concatenate the data as well as take care of the mime type header
...but it's not actually sending or receiving the response.
Ensure that the above is not invoked as a synchronous blocking call, like .Result, which could cause a deadlock.
For example, an async event handler can be used to make the async call
public async void onButtonClick(object sender, EventArgs args) {
//Non-blocking call
var tweetRequestCode = await PostStatusRequestAsync(TweetText, AuthUtils.GetResourceUrl(), AuthUtils.GetWebRequestHeader()));
//back on UI thread
//...
}
Reference Async/Await - Best Practices in Asynchronous Programming

Xamarin Forms Json Service Insert Data

I want to add a record to the json service in my application. How can I do this via Service Url. Here is my code.
CustomerModel customer = new CustomerModel();
customer.Name = entryCompanyName.Text;
customer.Title = entryCompanyTitle.Text;
customer.PhoneNumber = entryTelephone.Text;
customer.FaxNumber = entryFax.Text;
customer.Email = entryEmail.Text;
customer.CityId = 6444;
string json = JsonConvert.SerializeObject(customer);
string sContentType = "application/json";
string path = "service url";
HttpClient Client = new HttpClient();
var task = Client.PostAsync(path, new StringContent(json.ToString(), Encoding.UTF8, sContentType));
I'm trying M. Wiśnicki's solution, but I took this error
I did not get an error when I added System.net :( Where do i make mistakes?

This worked for me
public static async Task<string> PostEntityToApi<T>(string yourMethodUrl, T yourModel)
{
try
{
if (_httpClient == null)
{
_httpClient = new HttpClient { BaseAddress = new Uri(yourWebSiteUrl) };
}
var stringContentInput = new StringContent(JsonConvert.SerializeObject(dto), Encoding.UTF8, "application/json");
var response = await _httpClient.PostAsync(new Uri(yourWebSiteUrl. + apiUrl), stringContentInput);
if (!response.IsSuccessStatusCode)
{
throw new Exception(response.StatusCode.ToString());
}
var stringAsync = await response.Content.ReadAsStringAsync();
LoggingManager.Error("Received error response: " + stringAsync);
return stringAsync;
}
catch (Exception exception)
{
return null;
}
}

You can use WebRequest, this sample working for me, i use it in my app.
This is System.Net.WebRequest class, here you find doc.
public async Task<string> PostSample(object data, string uri)
{
// Create an HTTP web request using the URL:
var request = (HttpWebRequest) WebRequest.Create(new Uri(uri));
request.ContentType = "application/json";
request.Method = "POST";
var itemToSend = JsonConvert.SerializeObject(data);
using (var streamWriter = new StreamWriter(await request.GetRequestStreamAsync()))
{
streamWriter.Write(itemToSend);
streamWriter.Flush();
streamWriter.Dispose();
}
// Send the request to the server and wait for the response:
using (var response = await request.GetResponseAsync())
{
// Get a stream representation of the HTTP web response:
using (var stream = response.GetResponseStream())
{
var reader = new StreamReader(stream);
var message = JsonConvert.DeserializeObject<string>(reader.ReadToEnd());
return message;
}
}
}

Async request never ends using RestSharp

I'm using RestSharp to do a GET request Asynchronously but it never ends. If I do the same request Synchronously it ends successfully.
I have used RestSharp just like this before and it always worked.
What am I doing wrong?
Here's the async method: (this.Client is just localhost)
public async Task<ServiceResponse> UpvoteArticleAsync(string source, string url)
{
var client = this.Client;
var request = new RestRequest("service/upvote/"+source+"/"+url, Method.GET) { RequestFormat = DataFormat.Json };
var cancellationTokenSource = new CancellationTokenSource();
var deserial = new JsonDeserializer();
var response = await client.ExecuteTaskAsync(request, cancellationTokenSource.Token);
return deserial.Deserialize<ServiceResponse>(response);
}
and this is how I call it:
ServiceResponse result = await rest.UpvoteArticleAsync (this.article.Source, this.article.Url);
As I said if I change the async method to a sync one, it works:
public async Task<ServiceResponse> UpvoteArticleAsync(string source, string url)
{
var client = this.Client;
var request = new RestRequest("service/upvote/"+source+"/"+url, Method.GET) { RequestFormat = DataFormat.Json };
var cancellationTokenSource = new CancellationTokenSource();
var deserial = new JsonDeserializer();
var response = client.ExecuteTaskAsync(request, cancellationTokenSource.Token);
return deserial.Deserialize<ServiceResponse>(response.Result);
}
EDIT:
I used try and catch to see if there's any exceptions but it didn't throw any.
EDIT 2:
Even if I do the same request with HttpWebRequest from System.Net it still gets stuck when using the async version of GetResponse:
public async Task<bool> UpvoteArticleAsync(string source, string url)
{
var request = HttpWebRequest.Create(string.Format(#"http://192.168.43.199:8080/service/upvote/{0}/{1}", source, url));
request.ContentType = "application/json";
request.Method = "GET";
using (HttpWebResponse response = await request.GetResponseAsync () as HttpWebResponse)
{
if (response.StatusCode != HttpStatusCode.OK)
Console.Out.WriteLine("Error fetching data. Server returned status code: {0}", response.StatusCode);
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
var content = reader.ReadToEnd();
if(string.IsNullOrWhiteSpace(content)) {
Console.Out.WriteLine("Response contained empty body...");
}
else {
Console.Out.WriteLine("Response Body: \r\n {0}", content);
}
}
}
return true;
}

How to post JSON with HttpClient using C#?

I have no idea how to POST JSON with HttpClient. I find some solution, like this, but I have to use HttpClient, cause of async and have to add a header.
This is my code below. Any idea how to fix it?
List<Order> list = new List<Order> { new Order() { Name = "CreatedTime", OrderBy = 1 } };
Queues items = new Queues { Orders = list };
var values = new Dictionary<string, string> { { "Orders", JsonConvert.SerializeObject(list) } };
var content = new FormUrlEncodedContent(values);
//HttpContent cc = new StringContent(JsonConvert.SerializeObject(items));
_msg = await _client.PostAsync(input, content);
//_msg = await _client.PostAsync(input, cc);
var response = await _msg.Content.ReadAsStringAsync();

You can use the method PostAsJsonAsync which can be found in the extensions assemblies:
System.Net.Http.Formatting.dll
Example
public static async Task SendJsonDemo(object content)
{
using(var client = new HttpClient())
{
var response = await client.PostAsJsonAsync("https://example.com", content);
}
}
If you want to add custom headers to the request, add it to DefaultRequestHeaders:
client.DefaultRequestHeaders.Add("mycustom", "header1");

You can send any type of request like as
public static async Task<HttpResponseMessage> SendRequest(HttpMethod method, string endPoint, string accessToken, dynamic content = null)
{
HttpResponseMessage response = null;
using (var client = new HttpClient())
{
using (var request = new HttpRequestMessage(method, endPoint))
{
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);
if (content != null)
{
string c;
if (content is string)
c = content;
else
c = JsonConvert.SerializeObject(content);
request.Content = new StringContent(c, Encoding.UTF8, "application/json");
}
response = await client.SendAsync(request).ConfigureAwait(false);
}
}
return response;
}

Using a token to search on Twitter with OAuth2

Before Twitter switched to OAuth2, I was using the following query:
string atomTweetSearchURL = string.Format("http://search.twitter.com/search.atom?q={0}", searchText);
This no longer works, so now I'm trying to switch to OAuth2. I manage to successfully retrieve a token, but once I've got this, I seem to be unable to actually perform the search. Here's the latest incarnation of what I've tried:
var searchUrl = string.Format("https://api.twitter.com/1.1/search/tweets.json?q={0}&access_token={1}&token_type={2}", srchStr, twitAuthResponse.access_token, twitAuthResponse.token_type);
WebRequest srchRequest = WebRequest.Create(searchUrl);
using (var response2 = await srchRequest.GetResponseAsync())
{
Stream stream = response2.GetResponseStream();
using (StreamReader sr = new StreamReader(stream))
{
string jsonResponse = await sr.ReadToEndAsync();
}
}
This gives me a 400 - bad request.
I've also tried building the request like this:
System.Net.Http.HttpClient srchRequest = new System.Net.Http.HttpClient();
string authHdr = string.Format(srchHeaderFormat, twitAuthResponse.token_type, twitAuthResponse.access_token);
srchRequest.DefaultRequestHeaders.Add("Authorization", authHdr);
There's a massive quantity of articles out there detailing how to do this, but none of them seem to work correctly with WinRT. Can anyone point me in the right direction?
EDIT
Here's my code to get the token:
var oAuthConsumerKey = key;
var oAuthConsumerSecret = secret;
var oAuthUri = new Uri("https://api.twitter.com/oauth2/token");
var authHeaderFormat = "Basic {0}";
var authHeader = string.Format(authHeaderFormat,
Convert.ToBase64String(Encoding.UTF8.GetBytes(Uri.EscapeDataString(oAuthConsumerKey)
+ ":" +
Uri.EscapeDataString((oAuthConsumerSecret)))
));
var req = new HttpClient();
req.DefaultRequestHeaders.Add("Authorization", authHeader);
HttpRequestMessage msg = new HttpRequestMessage(new HttpMethod("POST"), oAuthUri);
msg.Content = new HttpStringContent("grant_type=client_credentials");
msg.Content.Headers.ContentType = new Windows.Web.Http.Headers.HttpMediaTypeHeaderValue("application/x-www-form-urlencoded");
HttpResponseMessage response = await req.SendRequestAsync(msg);
TwitAuthenticateResponse twitAuthResponse;
using (response)
{
string objectText = await response.Content.ReadAsStringAsync();
twitAuthResponse = JSonSerialiserHelper.Deserialize<TwitAuthenticateResponse>(objectText);
}

With the 1.1 API you don't pass the access token as part of the url, you need to include it as the Authorization header as "Bearer access_token" so you were almost there!
EDIT
To do this in the Windows.Web.Http namespace the following works:
private static async Task SearchTweets(AuthenticationResponse twitAuthResponse)
{
string srchStr = "tweet";
var client = new HttpClient();
var searchUrl = string.Format("https://api.twitter.com/1.1/search/tweets.json?q={0}", srchStr);
var uri = new Uri(searchUrl);
client.DefaultRequestHeaders.Authorization = new HttpCredentialsHeaderValue("Bearer", twitAuthResponse.AccessToken);
var response2 = await client.GetAsync(uri);
string content = await response2.Content.ReadAsStringAsync();
}
Or with System.Net.Http use the following:
This code will run the search for srchStr using the access token you already acquired as you showed in the first example:
var client = new HttpClient();
var searchUrl = string.Format("https://api.twitter.com/1.1/search/tweets.json?q={0}", srchStr);
var uri = new Uri(searchUrl);
client.DefaultRequestHeaders.Add("Authorization", string.Format("Bearer {0}", twitAuthResponse.access_token));
HttpResponseMessage response = await client.GetAsync(uri);
Task<string> content = response.Content.ReadAsStringAsync();
EDIT
This is a strange one, I tested your code and you're right it does throw an exception when attempting to add the Auth header, however the code I had used for grabbing the Access Token is almost identical but uses the System.Net.Http methods rather than the Windows.Web.Http ones that you use and it works, so I'll provide my code here, maybe this is a bug in the framework, or someone else can provide some more insight! This also uses the JSON.NET library which can be found on NuGet.
private static async Task SearchTweets(AuthenticationResponse twitAuthResponse)
{
string srchStr = "tweet";
var client = new HttpClient();
var searchUrl = string.Format("https://api.twitter.com/1.1/search/tweets.json?q={0}", srchStr);
var uri = new Uri(searchUrl);
client.DefaultRequestHeaders.Add("Authorization", string.Format("Bearer {0}", twitAuthResponse.AccessToken));
HttpResponseMessage response2 = await client.GetAsync(uri);
string content = await response2.Content.ReadAsStringAsync();
}
private async void GetAuthenticationToken()
{
var client = new HttpClient();
var uri = new Uri("https://api.twitter.com/oauth2/token");
var encodedConsumerKey = WebUtility.UrlEncode(TwitterConsumerKey);
var encodedConsumerSecret = WebUtility.UrlEncode(TwitterConsumerSecret);
var combinedKeys = String.Format("{0}:{1}", encodedConsumerKey, encodedConsumerSecret);
var utfBytes = System.Text.Encoding.UTF8.GetBytes(combinedKeys);
var encodedString = Convert.ToBase64String(utfBytes);
client.DefaultRequestHeaders.Add("Authorization", string.Format("Basic {0}", encodedString));
var data = new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("grant_type", "client_credentials")
};
var postData = new FormUrlEncodedContent(data);
var response = await client.PostAsync(uri, postData);
AuthenticationResponse authenticationResponse;
using (response)
{
if (response.StatusCode != System.Net.HttpStatusCode.OK)
throw new Exception("Did not work!");
var content = await response.Content.ReadAsStringAsync();
authenticationResponse = JsonConvert.DeserializeObject<AuthenticationResponse>(content);
if (authenticationResponse.TokenType != "bearer")
throw new Exception("wrong result type");
}
await SearchTweets(authenticationResponse);
}
}
class AuthenticationResponse
{
[JsonProperty("token_type")]
public string TokenType { get; set; }
[JsonProperty("access_token")]
public string AccessToken { get; set; }
}