REST service call

Question

I have to call method using REST service as I got some solution from material but getting error in await

public static Task RunAsync()
{
    string pathValue = WebConfigurationManager.AppSettings["R2G2APIUrl"];
    using (var client = new HttpClient())
    {
        client.BaseAddress = new Uri(pathValue);
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(
                    new MediaTypeWithQualityHeaderValue("application/json"));

        var id = "12421";
        HttpResponseMessage response = await client.GetAsync("api/products/1");
        var jobid = new Jobs() { Job_ID = id};
        response = await client.PostAsJsonAsync("api/products", jobid);
        if (response.IsSuccessStatusCode)
        {
            Uri gizmoUrl = response.Headers.Location;
        }
    }
}
static void Main()
{
    RunAsync().Wait();
}

await is not exist in current context as I am using vs2010 but is there any other solution for this?

@SílvioN. then I get an err of `the type or namespace async could not be found` in async — Dhara, Oct 14 '15 at 12:41
VS2010 doesn't supports/understand async-await. You need Vs2012 or later to make it work — Sriram Sakthivel, Oct 14 '15 at 12:50
@YuvalItzchakov Still the challenge is how to use async/await there — Sriram Sakthivel, Oct 14 '15 at 12:53
@SriramSakthivel He can't use async-await with VS2010. That makes it an impossible challange ;P. He can use `ContinueWith` instead. — Yuval Itzchakov, Oct 14 '15 at 12:54
@debin Why are you issuing a `GetAsync` request but then overriding the `response` immediately with `PostAsJsonAsync`? — Yuval Itzchakov, Oct 14 '15 at 13:05

Yuval Itzchakov · Accepted Answer · 2015-10-15T05:04:25.777

1

Instead of using await, you can use ContinueWith.

public static Task RunAsync()
{
    string pathValue = WebConfigurationManager.AppSettings["R2G2APIUrl"];
    var client = new HttpClient()
            client.BaseAddress = new Uri(pathValue);
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(
                new MediaTypeWithQualityHeaderValue("application/json"));
            var id = "12421";
        return client.GetAsync("api/products/1").ContinueWith(_ =>
    {
        var jobid = new Jobs() { Job_ID = id };
        return client.PostAsJsonAsync("api/products", jobid)
       .ContinueWith(responseTask =>
        {
          var gizmoUrl = responseTask.Result.IsSuccessStatusCode ?
                                        responseTask.Result.Headers.Location : null;
        });
    });
}

Note you have some redundancies in your code, like issuing a GetAsync request and doing nothing with the returned HttpResponseMessage.

edited Oct 15 '15 at 05:04

answered Oct 14 '15 at 13:12

Yuval Itzchakov

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m gettin error `Cannot access a disposed object.Object name: 'System.Net.Http.HttpClient'.` – Dhara Oct 15 '15 at 04:50
@debin You're right, I forgot to remove the `using` statement. Fixed it now. – Yuval Itzchakov Oct 15 '15 at 05:04
ah thnku so muchh..a little doubt..i will call this method as `RunAsync().Wait()` right? now I want to call a particular method which is in that `pathvalue`..any idea? – Dhara Oct 15 '15 at 05:35
@debin Sorry, I didn't understand your question. What is `pathvalue`? – Yuval Itzchakov Oct 15 '15 at 05:46
I am fetching URL from webconfig that is `pathvalue` – Dhara Oct 15 '15 at 05:48
@debin Ok, and what problem have you encountered? – Yuval Itzchakov Oct 15 '15 at 06:04
sorry m gettin err again of `responseTask.Result.IsSuccessStatusCode 'responseTask.Result' threw an exception of type 'System.AggregateException` I know its certificate related..but how to solve it??i dn want to export certificate – Dhara Oct 15 '15 at 06:28
What is the inner exception? – Yuval Itzchakov Oct 15 '15 at 06:32
the error is `{"An error occurred while sending the request."} and {"The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel."}` – Dhara Oct 15 '15 at 06:33
yah got it..jus last question..what this method will return??? because m calling it like `public bool restfunc(string id) { RunAsync(id).Wait(); return true; }`so how to save the result or check what is the return value? – Dhara Oct 15 '15 at 07:01

score 0 · Answer 2 · answered Oct 14 '15 at 13:22

Maybe you could just use the .Result of the async operation.

     public static Task RunAsync()
     {
        string pathValue = WebConfigurationManager.AppSettings["R2G2APIUrl"];
        using (var client = new HttpClient())
        {
            client.BaseAddress = new Uri(pathValue);
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            var id = "12421";
            HttpResponseMessage response = client.GetAsync("api/products/1").Result;
            var jobid = new Jobs() { Job_ID = id };
            response = client.PostAsJsonAsync("api/products", jobid).Result;
            if (response.IsSuccessStatusCode)
            {
                Uri gizmoUrl = response.Headers.Location;
            }
        }
    }

REST service call

2 Answers2