Calling REST service from C# code

Question

I am using the following code to call a REST service using C#

 string PostData= @"{""name"":""TestName""}";

 HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://something.com:1234/content/abc.v1.json");

        request.Method = "POST";
        request.ContentLength = 0;
        request.ContentType = ContentType;
        request.Accept = "application/json";
        request.KeepAlive = false;
        request.CookieContainer = cookie;

        if (!string.IsNullOrEmpty(PostData) && Method == HttpVerb.POST)
        {
            UTF8Encoding encoding = new UTF8Encoding();
            byte[] bytes = Encoding.GetEncoding("iso-8859-1").GetBytes(PostData);
            request.ContentLength = bytes.Length;
            request.AllowAutoRedirect = true;
            using (Stream writeStream = request.GetRequestStream())
            {
                writeStream.Write(bytes, 0, bytes.Length);
            }
        }

        try
        {  // Gets exception
            using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {

             ....
             }
        }

And I am getting an exception "400 bad request" on the line calling GetResponse(). The documentation of the service says the status code 400 means a required argument is missing. But as you can see the argument name (which is the only required argument ) is supplied with the request.

I tried to call the service with CURL and it successfully got executed.

curl -v -b cookie.txt -X POST -H "Content-Type: application/json" -d "{\"name\": \"TestName\"}" http://something.com:1234/content/abc.v1.json

So I assume there is something wrong with my C# code which doesn't seem to be passing the parameters. Any idea?

EDIT

Here is the relevant part of the documentation:

Method

POST

Headers

Content-Type: application/json

Body

The request body is made up of JSON containing the following properties:

Name : name Required : yes Type: string

Response Status codes

201 Created Success

400 Bad Request A required property is missing in the request body.

Consider using RestSharp; it's a fantastic interface for RESTful services. — Mike Perrenoud, Nov 19 '13 at 13:20
@MichaelPerrenoud: Thankz but 3rd party services are not allowed — Sharun, Nov 19 '13 at 13:39
Third party services? Or do you mean third party libraries? And what is the **actual** constraint there? — Mike Perrenoud, Nov 19 '13 at 13:40
Have you tried sending the data as a string instead of encoded bytes? The `StreamWriter` class would allow that. See example [here](http://stackoverflow.com/a/10027534/1346943) — Sven Grosen, Nov 19 '13 at 14:06
@MichaelPerrenoud I tried with RestSharp too, but the same exception occurs. I doubt, there is some problem with the service. But it works fine with Curl, and that is what makes me think there is something wrong in my part — Sharun, Nov 19 '13 at 14:25

score 1 · Answer 1 · answered Nov 19 '13 at 13:21

1

That's not how data is sent in a POST request. It should look like this:

string PostData= "name=TestName";

If you have more than one value, you separate them with the & character. Example:

string PostData= "name=TestName&number=20";

answered Nov 19 '13 at 13:21

Guffa

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But the documentation says it should be sent in the json format. and btw, i had already tried the method u suggested and it also resulted in the same exception – Sharun Nov 19 '13 at 13:25
I have added the relevant part of the documentation in the questiom – Sharun Nov 19 '13 at 13:32
@Sharun: Then it's not really a REST service... Anyway, what's in your `ContentType` variable? Is the response coming with the content type `application/json`? – Guffa Nov 19 '13 at 13:32
ContentType="application/json" – Sharun Nov 19 '13 at 13:33
@Sharun: You have set the `Accept` header to `application/json` also, is that the content type of the response? – Guffa Nov 19 '13 at 13:35
Ya on successful execution, the response should be json data. I am getting the json response using CURL – Sharun Nov 19 '13 at 13:37
@Sharun: Do you have the correct value in the `Method` variable, so that the code that sends the post data is executed? – Guffa Nov 19 '13 at 14:06
The code execute correctly till `using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())` – Sharun Nov 19 '13 at 14:23
@Sharun: Have you verified that the code in the `if` statement actually is executed? There is nothing in there that is needed to send the request, it's only needed to send the correct data in the request. – Guffa Nov 19 '13 at 14:26
Ya I checked line by line with the debugger, and checked the content length of request object too, to ensure that the data is there. I think the issue is something else. This code used to work fine for me with normal post, I mean those requests that send data like you said in your answer. – Sharun Nov 19 '13 at 14:30
What confuses me is the Curl call works fine with Json data and C# is failing – Sharun Nov 19 '13 at 14:30
@Sharun: I can't see anything else wrong with the code. I suggest that you try commenting out all settings that are not essential for the request, where the default values would work, for example the accept, keepalive and cookies. – Guffa Nov 19 '13 at 16:02

score 0 · Answer 2 · answered Nov 19 '13 at 15:53

I suggest using the System.Net.Http HttpClient class.

        string PostData = @"{""name"":""TestName""}";

        var httpClientHandler = new HttpClientHandler();
        httpClientHandler.CookieContainer = cookies;
        var httpClient = new HttpClient(httpClientHandler);

        var content = new StringContent(PostData, 
            Encoding.GetEncoding("iso-8859-1"), "application/json");

        httpClient.PostAsync("http://something.com:1234/content/abc.v1.json", content);

@Sharun Microsoft support .NET 4 also. http://www.nuget.org/packages/Microsoft.Net.Http/ — Darrel Miller, Nov 19 '13 at 17:29

Calling REST service from C# code

2 Answers2