I have followed the HttpClient samples but couldn't figure it out how to post a method with 2 parameters.
Below is what I tried but it return bad gateway error:
private async void Scenario3Start_Click(object sender, RoutedEventArgs e)
{
if (!TryUpdateBaseAddress())
{
return;
}
Scenario3Reset();
Scenario3OutputText.Text += "In progress";
string resourceAddress = "http://music.api.com/api/search_tracks";
try
{
MultipartFormDataContent form = new MultipartFormDataContent();
// form.Add(new StringContent(Scenario3PostText.Text), "data");
form.Add(new StringContent("Beautiful"), "track");
form.Add(new StringContent("Enimem"), "artist");
HttpResponseMessage response = await httpClient.PostAsync(resourceAddress, form);
}
catch (HttpRequestException hre)
{
Scenario3OutputText.Text = hre.ToString();
}
catch (Exception ex)
{
// For debugging
Scenario3OutputText.Text = ex.ToString();
}
}
I looked all over the internet, but couldn't find any working examples or documents that show how to perform the http post method. Any materials or samples would help me a lot.
Try FormUrlEncodedContent instead of MultipartFormDataContent:
var content = new FormUrlEncodedContent(
new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("track", "Beautiful"),
new KeyValuePair<string, string>("artist", "Enimem")
}
);
I prefer to take the following approach where you set the POST data into the request content body. Having to debug it is much easier!
Create your HttpClient object with the URL you're posting to:
string oauthUrl = "https://accounts.google.com/o/oauth2/token";
HttpClient theAuthClient = new HttpClient();
Form your request with the Post method to your url
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, oauthUrl);
Create a content string with your parameters explicitly set in POST data format and set these in the request:
string content = "track=beautiful" +
"&artist=eminem"+
"&rating=explicit";
request.Method = HttpMethod.Post;
request.Content = new StreamContent(new System.IO.MemoryStream(System.Text.Encoding.UTF8.GetBytes(content)));
request.Content.Headers.Add("Content-Type", "application/x-www-form-urlencoded");
Send the request and get a response:
try
{
HttpResponseMessage response = await theAuthClient.SendAsync(request);
handleResponse(response);
}
catch (HttpRequestException hre)
{
}
Your handler will be called once the request returns and will have response data from your POST. The following example shows a handler that you could put a breakpoint into to see what the response content is, at that point, you could parse it or do whatever you need to do with it.
public async void handleResponse(HttpResponseMessage response)
{
string content = await response.Content.ReadAsStringAsync();
if (content != null)
{
// put your breakpoint here and poke around in the data
}
}
Related
Im creating a list of components in Blazor, each one of these components need to request some data from a webpage. The list are created as follows on a .razor page:
#foreach(stringcomp in Complist){
<myComponent />
}
around 100 components are created. On all of these components the following URL request is preformed (using this code):
protected override async Task OnAfterRenderAsync(bool firstRender)
{
if (firstRender)
{
await GetUrl("some url here");
}
}
public async Task<string> GetUrl(string url)
{
HttpClient client = new HttpClient();
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("User-Agent", "get data service");
var response = await client.SendAsync(request).ConfigureAwait(false);
string res = null;
if (response.IsSuccessStatusCode)
{
using var responseStream = await response.Content.ReadAsStreamAsync().ConfigureAwait(false);
var streamReader = new StreamReader(responseStream);
res = await streamReader.ReadToEndAsync().ConfigureAwait(false);
}
return res;
}
Doing this I'm running in to some problems where most of my calls to SendAsync never returns a value. I have come to understand that this is because of a lock-state but for the life of me can't figure out how to solve it. most similar answers suggest setting .ConfigureAwait(false) but this does not yeald a different result in my case.
So my question is: Hos can i request webbpages simultaneously in different components and be sure that they won't hang/lookup. As theres many requests that some times takes a long time (5-10 sec) to complete it's not an alternative to do them synchronously.
It might also be of importance to mention that me code and pages are separated, every .razor page are using #inherits to get its functions/logic
Try to use IHttpClientFactory as follows:
[Inject] public IHttpClientFactory clientFactory { get; set;}
using System.IO;
Your GetUrl method:
public async Task<string> GetUrl(string url)
{
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/json");
request.Headers.Add("User-Agent", "get data service");
var client = clientFactory.CreateClient();
var response = await client.SendAsync(request);
string res = null;
if (response.IsSuccessStatusCode)
{
using var responseStream = await response.Content.ReadAsStreamAsync();
var streamReader = new StreamReader(responseStream);
res = await streamReader.ReadToEndAsync().ConfigureAwait(false);
}
return res;
}
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient();
// More code here...
}
Hope this works...
I use this code to upload images in asp.net webapi:
[HttpPost]
[Route("imageBrowser/insert")]
[SharePointContextWebAPIFilter]
public object PostFile()
{
HttpRequestMessage request = this.Request;
if (!request.Content.IsMimeMultipartContent())
{
throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);
}
string root = System.Web.HttpContext.Current.Server.MapPath("~/Content/images");
var provider = new MultipartFormDataStreamProvider(root);
Request.Content.ReadAsMultipartAsync(provider);
//return Request.CreateResponse(HttpStatusCode.OK);
return Request.CreateResponse(HttpStatusCode.OK);
}
The file is not being uploaded correctly, it looks like this
Is this related to azure? Is there something wrong with the code?
The problem is because you're using async code in a non async method. So the thread is being finished before ending the read part.
try this:
[HttpPost]
[Route("imageBrowser/insert")]
[SharePointContextWebAPIFilter]
public async object PostFile()
{
HttpRequestMessage request = this.Request;
if (!request.Content.IsMimeMultipartContent())
{
throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);
}
string root = System.Web.HttpContext.Current.Server.MapPath("~/Content/images");
var provider = new MultipartFormDataStreamProvider(root);
await Request.Content.ReadAsMultipartAsync(provider);
//return Request.CreateResponse(HttpStatusCode.OK);
return Request.CreateResponse(HttpStatusCode.OK);
}
I've got a simple web api which is consumed from a mvc project, I keep on getting the 'Response status code does not indicate success' and was wondering how would I get the response body from the error, I can see the error within a rest viewer but can't navigate through to the error. This is the following code within the MVC app
public ActionResult Index()
{
try
{
var uri = "http://localhost:57089/api/values";
using (var client = new HttpClient())
{
Task<string> response = client.GetStringAsync(uri);
object result = JsonConvert.DeserializeObject(response.Result);
return (ActionResult) result;
}
}
catch (Exception ex)
{
return Content(ex.ToString());
}
return View();
}
Within the API controller I'm sending a bad request, here's the code
public IHttpActionResult Get()
{
return BadRequest("this is a very bad request " + System.DateTime.Now.ToUniversalTime());
}
I've tried to use WebException, HttpRequestException as exceptions to catch the error with no luck.
I can see the response body within the rest viewer
I want to be able to navigate to the Error Message so I can pass that to the client (which later will be changed to a guid).
[EDITED]
I've got a solution without using GetStringAsync, but wanted to use that if possible.
Here's the solution
var httpClient = new HttpClient();
httpClient.BaseAddress = new Uri(url);
HttpResponseMessage responseMessage = httpClient.GetAsync("").Result;
if (responseMessage.IsSuccessStatusCode) return Content(responseMessage.ToString());
var a = responseMessage.Content.ReadAsStringAsync().Result;
var result = JsonConvert.DeserializeObject<HttpError>(a);
object value = "";
return Content(result.TryGetValue("ErrorMessage", out value) ? value.ToString() : responseMessage.ToString());
Is there a better way?
Using WebException you should be able to get to the ResponseStream and the custom error message like this:
catch (WebException e)
{
var message = e.Message;
using (var reader = new StreamReader(e.Response.GetResponseStream()))
{
var content = reader.ReadToEnd();
}
}
Hope that helps.
I'm attempting to build a GET webservice that would from website 1 initiate a GET request...sending that request to website 2 and website two would respond by sending a list of objects. I using Json.net to serialize and deserialize the List of objects.
I've put together a POST webservice with the assistance of this question.. WebService ASP.NET MVC 3 Send and Receive
But I've been unsuccessful so far at adapting that example for my new requirement.
Here is what I have so far from website 1..
public static List<ScientificFocusArea> ScientificFocusAreas()
{
string apiURL = "http://localhost:50328/Api/GetAPI";
//Make the post
ServicePointManager.ServerCertificateValidationCallback = (sender, certificate, chain, errors) => true;
//var bytes = Encoding.Default.GetBytes(body);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(apiURL);
Stream stream = null;
try
{
request.KeepAlive = false;
request.ContentType = "application/x-www-form-urlencoded";
request.Timeout = -1;
request.Method = "GET";
}
finally
{
if (stream != null)
{
stream.Flush();
stream.Close();
}
}
List<ScientificFocusArea> listSFA = WebService.GetResponse_ScientificFocusArea(request);
return listSFA;
}
public static List<ScientificFocusArea> GetResponse_ScientificFocusArea(HttpWebRequest request)
{
List<ScientificFocusArea> listSFA = new List<ScientificFocusArea>();
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
using (Stream responseStream = response.GetResponseStream())
{
if (response.StatusCode != HttpStatusCode.OK && response.StatusCode != HttpStatusCode.Created)
{
throw new HttpException((int)response.StatusCode, response.StatusDescription);
}
var end = string.Empty;
using (StreamReader reader = new StreamReader(responseStream))
{
end = reader.ReadToEnd();
reader.Close();
listSFA = JsonConvert.DeserializeObject<List<ScientificFocusArea>>(end);
}
response.Close();
}
}
return listSFA;
}
Then on the website 2...
public class GetAPIController : Controller
{
//
// GET: /Api/GetAPI/
[AcceptVerbs(HttpVerbs.Get)]
public ActionResult GetScientificFocusAreas()
{
//Get list of SFAs
List<ScientificFocusArea> ListSFA = CreateList.ScientificFocusArea();
string json = JsonConvert.SerializeObject(ListSFA, Formatting.Indented);
//Send the the seralized object.
return Json(json);
}
}
Also, on website 2, I've registered this route for the incoming request...
context.MapRoute(
"GetScientificFocusAreas",
"Api/GetAPI/",
new
{
controller = "GetAPI",
action = "GetScientificFocusAreas",
id = UrlParameter.Optional
}
);
I'm currently getting the error.. he remote server returned an error: (404) Not Found.
Any help would me greatly appreciated.
The problem seems like a routing issue. I would start with the RouteDebugger which can be found here. This tool gives insight into which routes your URL is hitting.
The code I use for a HTTP GET is a bit different that what you have above. It's included below.
public T Get<T>(string url)
{
try
{
HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
using (Stream responseStream = response.GetResponseStream())
{
if (response.StatusCode != HttpStatusCode.OK && response.StatusCode != HttpStatusCode.Created)
{
throw new HttpException((int)response.StatusCode, response.StatusDescription);
}
var end = string.Empty;
using (StreamReader reader = new StreamReader(responseStream))
{
end = reader.ReadToEnd();
reader.Close();
}
responseStream.Close();
response.Close();
JsonSerializer serializer = new JsonSerializer();
serializer.Binder = new DefaultSerializationBinder();
JsonReader jsonReader = new JsonTextReader(new StringReader(end));
T deserialize = serializer.Deserialize<T>(jsonReader);
return deserialize;
}
}
catch (Exception ex)
{
throw new ApiException(string.Format("An error occured while trying to contact the API. URL: {0}", url), ex);
}
}
The other issue I see is in the GetScientificFocusAreas() method. On the second line of the code the objects are converted to JSON. Which is fine, but the last line of code the json is passed into the Json() method. Which converts the string into Json yet again. When using the JSON.Net library use the Content() method in the return instead of Json() and set the content type to application/json
The reasoning for using an external Json converter rather than the internal converter is simply the internal json converter has a few known issues. JSON.Net has been around for years and is solid.
I'm trying to validate a user in my WP7 app by validating username/pass on a server.
In my "validate user" method I create a HTTPWebRequest with the stuff I need validated.
Then as far as I can see, the only option to execute is to use request.BeginGetResponse, with an async callback.
But I want to return the response from the request in the same method that I created the request in, how can I accomplish this?
I'm not sure why you would like to make it return in the calling method. I would just use the standard WebClient behavior like below:
public void ValidateUser()
{
WebClient webClient = new WebClient();
Uri uri = new Uri(url);
webClient.DownloadStringCompleted += new DownloadStringCompletedEventHandler(webClient_DownloadStringCompleted);
webClient.DownloadStringAsync(new Uri(url));
}
void webClient_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
//Validate result from response by using e.Result
}
BeginGetResponse returns an IAsyncResult which has a wait handle that is signalled when the request completes. All you have to do is wait on this handle: [ doesn't work on WP7 ]
UPDATE: use a ManualResetEvent
var mre = new ManualResetEvent( false );
var iar = myHttpWebRequest.BeginGetResponse( state => mre.Set(), null );
mre.WaitOne();
var response = myHttpWebRequest.EndGetResponse( iar );
The only real way to achieve what you need would be to create an event in your worker class, and fire that event when the async call completes, so (pseudocode)...
void StartDownload(object[] parameters)
{
var req = HttpWebRequest.Create("http://google.com");
req.BeginGetRequestStream(Completed_handler, req);
}
void Completed_handler(object sender, DownloadStringCompletedEventArgs e)
{
var request = (HttpWebRequest)result.AsyncState;
var response = request.EndGetResponse(result);
using (var stream = response.GetResponseStream())
using (var reader = new StreamReader(stream))
{
var contents = reader.ReadToEnd();
NotifyCallerOfContent(contents)
}
}
public event EventHandler<MyCustomEventArgsClass> DownloadHasFinished;
public NotifyCallerOfDownload(string content)
{
if(null != DownloadHasFinished)
{
DownloadHasFinished(this, new MyCustomEventArgsClass(content));
}
}
and then subscribe to the DownloadHasFinished event in your calling class.
As for calling out specifically by a HttpWebRequest, take a look at this question, where you will find some working samples.