How to implement the await keyword? - api

Question

I have written a code to get the projects from the TFS 2013 server using the tfs web api. As the methord is taking too long to execute i.e like 1.5 minutes, so i wanted to make this methord as async. So i added the async and task in the return type. When i see in visual studio is shows a message that the methord does not have await keyword. where should i add the await keyword. I am very new to async programming.
public override async Task<List<Project>> GetProjects()
{
List<Project> retunResult = new List<Project>();
using (var http = new HttpClient(GetHttpHandler()))
{
var response = http.GetAsync(_baseUrl + "_apis/projectCollections?" + tfsWebApiVersionSring).Result;
if (response.IsSuccessStatusCode)
{
response.EnsureSuccessStatusCode();
TFS2013TeamProjectCollection.Rootobject obj = JsonConvert.DeserializeObject<TFS2013TeamProjectCollection.Rootobject>(response.Content.ReadAsStringAsync().Result);
if (obj != null)
{
foreach (TFS2013TeamProjectCollection.Value projColl in obj.value)
{
if (projColl.state == "Started")
{
var responseProj = http.GetAsync(_baseUrl + projColl.name + "/_apis/projects?" + tfsWebApiVersionSring).Result;
if (responseProj.IsSuccessStatusCode)
{
responseProj.EnsureSuccessStatusCode();
TFS2013TeamProject.Rootobject obj1 = JsonConvert.DeserializeObject<TFS2013TeamProject.Rootobject>(responseProj.Content.ReadAsStringAsync().Result);
if (obj1 != null)
{
Project p;
foreach (TFS2013TeamProject.Value TeamProj in obj1.value)
{
p = new Project();
p.collectionName = TeamProj.collection.name;
p.description = TeamProj.description;
p.id = TeamProj.id;
p.name = TeamProj.name;
p.collectionName = TeamProj.collection.name;
p.url = TeamProj.url;
retunResult.Add(p);
}
}
}
}
}
return retunResult;
}
}
}
return null;
}

Answer 1

You could refer to this code snippet about using TFS REST API to get something in async way.
public static async void RESTAPIMethod()
{
HttpClientHandler authtHandler = new HttpClientHandler()
{
Credentials = CredentialCache.DefaultNetworkCredentials
};
using (HttpClient client = new HttpClient(authtHandler))
{
client.DefaultRequestHeaders.Accept.Add(
new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
using (HttpResponseMessage response = client.GetAsync(
"Put the REST API URL here").Result)
{
response.EnsureSuccessStatusCode();
var responseBody = await response.Content.ReadAsStringAsync();
}
}
}
Another method about using TFS REST API:
You could also install this Nuget package for your project. Then using these assemblies in this package to run a REST API with C#. This is different with the method above, it's much more convenient. Here is an example about get a build information using Microsoft.TeamFoundation.Build.WebApi assembly in Async method.
Example:
What object returns from TFS2015 RestAPI

Answer 2

You shouldn't use Result at all. Every place in your code where you have:
var resp = http.GetAsync(url).Result;
you should have:
var resp = await http.GetAsync(url);