WebApi: Reading errors - model-view-controller

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.

Related

Why base64 image is big ? xamarin forms

I am facing one error sometimes, when I try get a picture from user gallery.
I get the picture in a Stream object, convert it to a base64 and I send it using a post function.
Sometimes The program says that the image path is big and, because of that, its not possible send the url.
I heard that its cause the image size but I am not sure about it...
Does someone know what really causes a Big base64 string? How can I solve that?
You could follow something similar to this:
http://jamessdixon.wordpress.com/2013/10/01/handling-images-in-webapi/
Maybe you need make some change in your web api like this:
[HttpPost]
public HttpResponseMessage UploadImage(int ID)
{
var result = new HttpResponseMessage(HttpStatusCode.OK);
if (Request.Content.IsMimeMultipartContent())
{
Request.Content.LoadIntoBufferAsync().Wait();
Request.Content.ReadAsMultipartAsync(new MultipartMemoryStreamProvider()).ContinueWith((task) =>
{
MultipartMemoryStreamProvider provider = task.Result;
foreach (HttpContent content in provider.Contents)
{
Stream stream = content.ReadAsStreamAsync().Result;
Image image = Image.FromStream(stream);
var testName = content.Headers.ContentDisposition.Name;
String filePath = HostingEnvironment.MapPath("~/Content/");
String fullPath = Path.Combine(filePath, ID.ToString()+".jpg");
image.Save(fullPath);
}
});
return result;
}
else
{
throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotAcceptable, "This request is not properly formatted"));
}
}
After making sure your api web works well you should change from Stream to byte[]
In your Xamarin code try this:
public async Task PostItem(String Controller, String Method, int ID, byte[] item)
{
using (var client = CreateClient ()) {
var da = new ByteArrayContent(item);
try{
var multi = new MultipartContent();
multi.Add(da);
var response = await client.PostAsync (Controller + "/" +Method + "/?ID=" +ID, multi);
}catch(Exception ex)
{
Console.Write(ex.Message);
}
}
}
For more infomation see MultipartContent class documentation

Image cut after being uploaded to webapi

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);
}

MVC 3 GET Webservice and Response

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.

how to perform post method in windows 8 metro?

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
}
}

Populating a WP7 List from a webservice causes 'Invalid cross-thread access.'

Sorry if this is a easy question but I am totally new to WP7.
I have a rest service that I am trying to consume however I get an error 'Invalid cross-thread access.'
This is my code
public ObservableCollection<TransactionViewModel> Transactions { get;private set; }
public MainViewModel()
{
this.Transactions = new ObservableCollection<TransactionViewModel>();
}
public void LoadTransactions(string id)
{
var req = (HttpWebRequest)WebRequest.Create(string.Format("http://domain.com/Transactions?Id={0}", id));
req.Method = "POST";
req.ContentType = "application/json; charset=utf-8";
// call async
req.BeginGetResponse(new AsyncCallback(jsonGetRequestStreamCallback), req);
this.IsDataLoaded = true;
}
void jsonGetRequestStreamCallback(IAsyncResult asynchronousResult)
{
WebResponse response = ((HttpWebRequest)asynchronousResult.AsyncState).EndGetResponse(asynchronousResult);
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
string responseString = reader.ReadToEnd();
reader.Close();
var s = JsonConvert.DeserializeObject<List<TransactionViewModel>>(responseString);
foreach (var t in s)
{
Transactions.Add(new TransactionViewModel()
{
.........
}
}
Have I done something really stupid here?
When you come back from the request you are no longer on the UI thread. So you need to switch control back to the UI thread before performing any actions that will affect the UI.
You are updating an ObservableCollection, which will be bound on the UI and therefore the update is going to affect the UI.
There are a number of approaches, the simplest for you purposes will be
Deployment.Current.Dispatcher.BeginInvoke(()=> {
foreach (var t in s) {
Transactions.Add(new TransactionViewModel());
}
});
Edit: Also if you want to read a little more about this, I have a blog post about it here http://csainty.blogspot.com/2010/10/windows-phone-7asynchronous-programming.html it starts from code like yours that looks reasonable and should work, explains a few of the gotchas and how to get it working.

Resources