How to await a list of tasks asynchronously using LINQ?
async-await, c#, linq
Solution
LINQ doesn't work perfectly with `async` code, but you can do this:
var tasks = foos.Select(DoSomethingAsync).ToList();
await Task.WhenAll(tasks);
If your tasks all return the same type of value, then you can even do this:
var results = await Task.WhenAll(tasks);
which is quite nice. `WhenAll` returns an array, so I believe your method can return the results directly:
return await Task.WhenAll(tasks);
Problem
I have a list of tasks that I created like this: ``` public async Task<IList<Foo>> GetFoosAndDoSomethingAsync() { var foos = await GetFoosAsync(); var tasks = foos.Select(async foo => await DoSomethingAsync(foo)).ToList(); ... } ``` By using `.ToList()`, the tasks should all start. Now I want to await their completion and return the results. This works in the above `...` block: ``` var list = new List<Foo>(); foreach (var task in tasks) list.Add(await task); return list; ``` It does what I want, but this seems rather clumsy. I'd much rather write something simpler like this: ``` return tasks.Select(async task => await task).ToList(); ``` ... but this doesn't compile. What am I missing? Or is it just not possible to express things this way?