Re-factored async get api request not awaiting data.

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Hello guys/girls i am having a bit of problem. i have a method that performs a get request. this method works. so i re-factored the method, so that certain parts can be used for other methods.

//Original Method
public async Task<T> GetByIdAsync(T returnType, T1 controllerName, T2 Id)
{
  var url = baseUrl + controllerName + "/" + Id;
  var result = returnType;
  using (HttpClient client = new HttpClient())
  {
     client.BaseAddress = new Uri(url);
     client.DefaultRequestHeaders.Accept.Clear();
     client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));

      var response = await client.GetAsync(url);
      if (response.IsSuccessStatusCode)
      {
         var data = response.Content.ReadAsStringAsync();
          result = JsonConvert.DeserializeObject(data.Result);
       }
    }
}


//refactored method        
public async Task<T> GetByIdAsync<T, T1, T2>(T returnType, T1 controllerName, T2 Id)
{
    var url = baseUrl + controllerName + "/" + Id;
    var result = returnType;
    var client = GetClient(url);

    var response = await client.GetAsync(url);
    if (response.IsSuccessStatusCode)
    {
        var data = response.Content.ReadAsStringAsync();
        result = JsonConvert.DeserializeObject<T>(data.Result);
    }
    return result;
}

public static HttpClient GetClient(string url)
{
    using (HttpClient client = new HttpClient())
    {
        client.BaseAddress = new Uri(url);
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));

        return client;
    }
}

After i re-factored the method, it no longer awaits. what is wrong ? .

What I have tried:

the original code works, i am trying to understand why the re-factored code doesn't work

Posted 15-May-17 5:32am

rudolph098

Updated 15-May-17 6:03am

v2

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F-ES Sitecore · Accepted Answer · 2017-05-15T06:03:00

Solution 1

"using" disposes (destroys) an object when it leaves the using context, so your HttpClient is not usable outside of the GetClient method. Remove the "using"

C#

public static HttpClient GetClient(string url)
{
    HttpClient client = new HttpClient();
    client.BaseAddress = new Uri(url);
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
 
    return client;
}

Posted 15-May-17 6:03am

F-ES Sitecore

Comments

rudolph098 15-May-17 12:16pm

Thanks, it now works. But are there any possible side effects that may arise from removing the using statement in the GetClient(url) method ?

F-ES Sitecore 15-May-17 12:21pm

None, it's just a short-hand way of writing this

HttpClient client;
try
{
client = new HttpClient();
client.BaseAddress = new Uri(url);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));

return client;
}
catch
{
throw;
}
finally
{
client.Dispose();
}

The important bit is the call to Dispose in "finally", that's why you use "using" and that's exactly the line you don't need.

rudolph098 15-May-17 12:25pm

Thanks for the explanation

Richard Deeming 16-May-17 10:51am

Confusingly, even though it implements IDisposable, the HttpClient should almost never be wrapped in a using statement:
You're using HttpClient wrong and it is destabilizing your software : ASP.NET Monsters[^]

rudolph098 16-May-17 11:55am

Wow!!!!, thanks for this insightful article.