I am using C#
in my code, I call API
This API returns a string.
But the problem is when I read the API it comes with backslashes and quotations.
So if the returned value is Black\White's colors
It becomes "\"Black\\\\White's colors\""
or empty string is "\"\""
I wonder if there is a way to parse string the in a right way.
here is my code
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
string str = client.GetStringAsync(url).Result;
Like this
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
string str = await client.GetStringAsync(url);
//choose this if using NewtonsoftJson
string parsedWithNewtonsoft = JsonConvert.DeserializeObject<string>(str);
//choose this if using STJ
string parsedWithSystemTextJson = JsonSerializer.Deserialize<string>(str);
Choose one of the last two lines according to your preferred installed Json parser (manage nuget packages for the project and install either newtonsoft or system.text.json)
Don't use Result; use async proper (which means you have to make your method calls async all the way up the chain). If you strive to turn all your async calls synchronous then your app will spend a lot of tine sitting around doing nothing, waiting for network io to finish, when that time could be put to doing other useful work
Also, HttpClient is not supposed to be created anew every time you want to use it. Either configure your DI with services.AddHttpClient(); passing in options as necessary or if you aren't using DI/not writing a service of your own, you can get some ideas on how to use HttpClientFactory to manufacture HttpClients for you form this question - you may even be able to configure the default request headers as part of the manufacture so you don't need to set them in code
Finally, I should point out that I think there's a chance you're doing a lot more work than you need to if your API you're using publishes a swagger document; if it does you can use a tool like AutoRest (or the "add rest client" feature of visual studio, which uses AR), NSwag, WebApiClientGen etc and tell it "here is the api I want to use" and it'll make everything you need to call the api and return c# objects; you don't need to code any of this low level stuff, pushing data around and parsing responses, yourself
Related
I'm making an http request post to an external api. I am constructing a json object to add to the request body. How can I check if the added body/content is correct before it is sent.
public async void TestAuthentication()
{
var client = new HttpClient();
var request = new HttpRequestMessage()
{
RequestUri = new Uri("http://test"),
Method = HttpMethod.Post
};
var jsonObj = new
{
data = "eneAZDnJP/5B6r/X6RyAlP3J",
};
request.Content = new StringContent(JsonConvert.SerializeObject(jsonObj), Encoding.UTF8, "application/json");
var response = await client.SendAsync(request);
}
If you are not sure whether the serialization works as intended, you could give it a shot in LINQpad or dotnetfiddle.net. See my example that returns the JSON on the console. These tools are great for quick prototyping a method or a snippet, if you are not sure if a piece of code works as intended.
You could also check in Wireshark, but that could be a bit of an overkill and works best if your connection if not encrypted (no HTTPS).
I personally tend to test code that calls some API the following way:
Make the called URL parameterizable (via the classes constructor)
If there is any variable data this data should be passed as the methods parameter(s)
For your test start an HTTP server from your test fixture (read on testing with xUnit or NUnit if you don't know what this means)
I use PeanutButter.SimpleHTTPServer for that
Pass the local IP to the class that accesses the API
Check whether the HTTP server received the expected data
Whether or not this kind of code shall be tested (this way) may be debatable, but I found this way to work kind of good. I used to abstract the HttpClient class away, but IMHO I would not recommend this anymore, because if the class accesses the API (and does not do anything else, which is important), the HTTP access is the crucial part that shall be tested and not mocked.
I am trying to do some load testing with
https://loader.io/
I am currently stuck at the stage of "verifying" my localHost application to make sure I am the one controlling it.
I have added this end point:
[HttpGet("/loaderio-a65421134i3ia3d110vcv0120d1ac14b/")]
[Authorize()]
public StreamReader GetLoaderIO()
{
var file = System.IO.File.OpenText(#"C:\Users\User\Downloads\loaderio-a65421134i3ia3d110vcv0120d1ac14b.txt");
return file;
}
When I run a GET request to this URL
http://localhost:5012/loaderio-a65421134i3ia3d110vcv0120d1ac14b/
I successfully step in my end point, what do I need to return in order for the LoaderIO to be happy? Do I have to return the stream so it can be downloaded?
I can see three potential issues with your code.
First, you are targeting a localhost address instead of a deployment address (i.e. http://yourapi.com or 159.254.102.69). To fix that issue you will need to either deploy your code somewhere or open http ports from your machine.
Second the file you are trying to retrieve my not be at the same location or might not even be accessible so a simpler way would be to write the string directly (done multiple time to verify on loader.io works like a charm) like below:
[HttpGet]
[Route("loaderio-a65421134i3ia3d110vcv0120d1ac14b")]
public HttpResponseMessage GetLoaderIoVerification()
{
var response = Request.CreateResponse(HttpStatusCode.OK);
response.Content = new StringContent("loaderio-a65421134i3ia3d110vcv0120d1ac14b", Encoding.UTF8, "text/plain");
return response;
}
Finally, there is that Authorize attribute that will try to authenticate the loader.io request that needs to be a resource as accessible as this one: https://media4.giphy.com/media/LXONhtCmN32YU/giphy.gif In order to do so you will need to remove it.
Once those three points are corrected you will be able to verify your api for loader.io. Hope it helps.
I'm using the sendgrid api here:
https://sendgrid.com/docs/API_Reference/Web_API_v3/Marketing_Campaigns/contactdb.html#Delete-a-Recipient-DELETE
and it shows passing an array of strings to the DELETE call. When I look at the signature of System.Net.Http.HttpClient, DELETE does not allow for content to be passed in.
Is there a standard around DELETE that does not allow for multiple content passed at the same time?
API definition:
The HTTP/1.1 RFC states that a DELETE request's payload has no defined semantics.
It's not illegal to include a payload, but this means that if a payload is included, it should be ignored.
Many HTTP clients, such as the one provided by the .NET framework, don't provide an interface to include a payload when it has no defined semantics for the method.
Unfortunately, many REST APIs do require a payload with these methods. You can accomplish this by manually creating a HttpRequestMessage object, setting the Method and Content properties, and passing it to the HTTP client's SendAsync method.
Create an extension method
public static class HttpClientExtensions
{
public static Task<HttpResponseMessage> Delete(this HttpClient client, HttpContent content)
{
var request = new HttpRequestMessage { Method = "DELETE", Content = content);
return client.SendAsync(request);
}
}
However I cannot recommend it, as it breaks basic assumptions of HTTP, which allows efficient HTTP Proxies to work.
The "correct method" around this problem is to use HTTP 2.0 (or HTTP 1.1 Pipelining, which is deprecated due to it being mostly broken, but you could try it out) to create multiple DELETE requests. In theory that solution does not require any code change.
I have created a simple web api controller in mvc4 containing 4 methods (one for each CRUD operation). I'm able to use fiddler to test that the methods in my controller work.
I'm now trying to make a unit test to prove that these work. I've managed to serialize my client side object into json format, but now how do I use this string of json to actually invoke my methods?
If it helps, I am using Json.NET to serialize my client object - although I don't think this extention actually handles the delivery and retreival of it to the server.
Your unit tests should be written against the controller - so you don't need to make an actual HTTP request to unit test your Web API code, you just call the methods.
From a design perspective, if you want a restful Web API, the client should be able to send a standard HTTP message without having to serialize the request.
This is the kind of approach I have used to post an object to a restful Web API:
HttpResponseMessage response;
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("http://url_to_service");
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var responseTask = client.PostAsJsonAsync("api/resource/somethingelse", someObjectToPost).Result;
responseTask.Wait();
response = responseTask.Result;
if (response.IsSuccessStatusCode)
{
var contentTask = response.Content.ReadAsAsync<SomeResponseType>();
contentTask.Wait();
SomeResponseType responseContent = contentTask.Result;
}
else
{
//Handle error.
}
In this case, someObjectToPost is your client-side object, though you can leave it to Web API to serialize it for you. In the above example I am assuming the reponse is of fictional type SomeResponseType - you can also use ReadAsStringAsync if the response is expected to be plain text.
The code presented here by nick_w is correct. You need to use HttpClient object. And as Steve Fenton mentioned, to create unit test you don't want to do it - rather test directly against controller. But for the functional test you can do it. I've done same thing. I've created helper class so I need only to call one of Http helper methods, depending if it is GET or POST, etc. that I do. This helper uses generic types so it operates with any types that being passed.
When using the System.Net.WebClient.DownloadData() method I'm getting an unreasonably slow response time.
When fetching an url using the WebClient class in .NET it takes around 10 sec before I get a response, while the same page is fetched by my browser in under 1 sec.
And this is with data that's 0.5kB or smaller in size.
The request involves POST/GET parameters and a user agent header if perhaps that could cause problems.
I haven't (yet) tried if other ways to download data in .NET gives me the same problems, but I'm suspecting I might get similar results. (I've always had a feeling web requests in .NET are unusually slow...)
What could be the cause of this?
Edit:
I tried doing the exact thing using System.Net.HttpWebRequest instead, using the following method, and all requests finish in under 1 sec.
public static string DownloadText(string url)
var request = (HttpWebRequest)WebRequest.Create(url);
var response = (HttpWebResponse)request.GetResponse();
using (var reader = new StreamReader(response.GetResponseStream()))
{
return reader.ReadToEnd();
}
}
While this (old) method using System.Net.WebClient takes 15-30s for each request to finish:
public static string DownloadText(string url)
{
var client = new WebClient();
byte[] data = client.DownloadData(url);
return client.Encoding.GetString(data);
}
I had that problem with WebRequest. Try setting Proxy = null;
WebClient wc = new WebClient();
wc.Proxy = null;
By default WebClient, WebRequest try to determine what proxy to use from IE settings, sometimes it results in like 5 sec delay before the actual request is sent.
This applies to all classes that use WebRequest, including WCF services with HTTP binding.
In general you can use this static code at application startup:
WebRequest.DefaultWebProxy = null;
Download Wireshark here http://www.wireshark.org/
Capture the network packets and filter the "http" packets.
It should give you the answer right away.
There is nothing inherently slow about .NET web requests; that code should be fine. I regularly use WebClient and it works very quickly.
How big is the payload in each direction? Silly question maybe, but is it simply bandwidth limitations?
IMO the most likely thing is that your web-site has spun down, and when you hit the URL the web-site is slow to respond. This is then not the fault of the client. It is also possible that DNS is slow for some reason (in which case you could hard-code the IP into your "hosts" file), or that some proxy server in the middle is slow.
If the web-site isn't yours, it is also possible that they are detecting atypical usage and deliberately injecting a delay to annoy scrapers.
I would grab Fiddler (a free, simple web inspector) and look at the timings.
WebClient may be slow on some workstations when Automatic Proxy Settings in checked in the IE settings (Connections tab - LAN Settings).
Setting WebRequest.DefaultWebProxy = null; or client.Proxy = null didn't do anything for me, using Xamarin on iOS.
I did two things to fix this:
I wrote a downloadString function which does not use WebRequest and System.Net:
public static async Task<string> FnDownloadStringWithoutWebRequest(string url)
{
using (var client = new HttpClient())
{
//Define Headers
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var response = await client.GetAsync(url);
if (response.IsSuccessStatusCode)
{
string responseContent = await response.Content.ReadAsStringAsync();
//dynamic json = Newtonsoft.Json.JsonConvert.DeserializeObject(responseContent);
return responseContent;
}
Logger.DefaultLogger.LogError(LogLevel.NORMAL, "GoogleLoginManager.FnDownloadString", "error fetching string, code: " + response.StatusCode);
return "";
}
}
This is however still slow with Managed HttpClient.
So secondly, in Visual Studio Community for Mac, right click on your Project in the Solution -> Options -> set HttpClient implementation to NSUrlSession, instead of Managed.
Screenshot: Set HttpClient implementation to NSUrlSession instead of Managed
Managed is not fully integrated into iOS, doesn't support TLS 1.2, and thus does not support the ATS standards set as default in iOS9+, see here:
https://learn.microsoft.com/en-us/xamarin/ios/app-fundamentals/ats
With both these changes, string downloads are always very fast (<<1s).
Without both of these changes, on every second or third try, downloadString took over a minute.
Just FYI, there's one more thing you could try, though it shouldn't be necessary anymore:
//var authgoogle = new OAuth2Authenticator(...);
//authgoogle.Completed...
if (authgoogle.IsUsingNativeUI)
{
// Step 2.1 Creating Login UI
// In order to access SFSafariViewController API the cast is neccessary
SafariServices.SFSafariViewController c = null;
c = (SafariServices.SFSafariViewController)ui_object;
PresentViewController(c, true, null);
}
else
{
PresentViewController(ui_object, true, null);
}
Though in my experience, you probably don't need the SafariController.
Another alternative (also free) to Wireshark is Microsoft Network Monitor.
What browser are you using to test?
Try using the default IE install. System.Net.WebClient uses the local IE settings, proxy etc. Maybe that has been mangled?
Another cause for extremely slow WebClient downloads is the destination media to which you are downloading. If it is a slow device like a USB key, this can massively impact download speed. To my HDD I could download at 6MB/s, to my USB key, only 700kb/s, even though I can copy files to this USB at 5MB/s from another drive. wget shows the same behavior. This is also reported here:
https://superuser.com/questions/413750/why-is-downloading-over-usb-so-slow
So if this is your scenario, an alternative solution is to download to HDD first and then copy files to the slow medium after download completes.