I want to make a webservice request asynchron. I call it here:
List<Item> list = GetListAsync();
Here is the declaration of my function, which should return a list:
private async Task<List<Item>> GetListAsync(){
List<Item> list = await Task.Run(() => manager.GetList());
return list;
}
If I want to compile I get the following error
Cannot implicitely convert type System.Threading.Tasks.Task<System.Collections.Generic.List<Item>> to System.Collections.Generic.List<Item>
As I know If I use the async
modifier the result is automatically wrapped with Task. I think this doesn't happen because I use Task.Run
. If I remove the Task.Run(() =>
part I get
Cannot await System.Collections.Generic.List expression
I think I haven't fully understood the async/await methods. What I'm doing wrong?
You need to correct your code to wait for the list to be downloaded:
List<Item> list = await GetListAsync();
Also, make sure that the method, where this code is located, has async
modifier.
The reason why you get this error is that GetListAsync
method returns a Task<T>
which is not a completed result. As your list is downloaded asynchronously (because of Task.Run()
) you need to "extract" the value from the task using the await
keyword.
If you remove Task.Run()
, you list will be downloaded synchronously and you don't need to use Task
, async
or await
.
One more suggestion: you don't need to await in GetListAsync
method if the only thing you do is just delegating the operation to a different thread, so you can shorten your code to the following:
private Task<List<Item>> GetListAsync(){
return Task.Run(() => manager.GetList());
}