CODEWITHSUNDEEP
c#asynchronous
ztorstri
ztorstri

Reputation: 389

await multiple tasks and access results

I need to run multiple awaitable tasks, and then gather their results into a list and return it.

I can create the tasks in a loop and use Task.WhenAll to await them, but I can't figure out how to access the results of each awaited task. I tried the below but Result is not defined.

    List<Service> services = new List<Service>();
    List<Exception> exceptions = new List<Exception>();
    List<Task<Service>> tasks = new List<Task<Service>>();

    foreach (string serviceMoniker in monikers)
    {
      try
      {
        tasks.Add(GetService(serviceMoniker, tenantMoniker, countryCode, environmentId));
      }
      catch (Exception e) { exceptions.Add(e); }
    }

    var continuation = Task.WhenAll(tasks);

    for (int i=0; i < continuation.Result.Length - 1; i++)
    {
      services.Add(continuation.Result[i].Result);
    }

another attempt

    await Task.WhenAll(tasks);

    foreach (Task t in tasks)
    {
      services.Add(t.Result);
    }

Upvotes: 3

Views: 3540

Answers (2)

Jcl
Jcl

Reputation: 28272

You are iterating (on the foreach) to a Task variable (which doesn't have a typed Result), you need to iterate to a Task<Service> variable (or use var, since your tasks list is already typed), that is:

foreach (var t in tasks)
{
  services.Add(t.Result);
}

Upvotes: 4

ztorstri
ztorstri

Reputation: 389

I was missing the generic part of the Task in the loop. Changed this

await Task.WhenAll(tasks);

foreach (Task t in tasks)
{
  services.Add(t.Result);
}

to this

await Task.WhenAll(tasks);

foreach (Task<Service> t in tasks)
{
  services.Add(t.Result);
}

and now it works

Upvotes: 4

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