Await an async function from setter property

Question

I need to await to an async function from a property setter method.

public String testFunc()
{
get
{

}
set
{
    //Await Call to the async func <asyncFunc()>

}
}

I understand we should not make async properties, so what is the optimal way to do this.

Show this post, i think this is your solution http://stackoverflow.com/questions/6602244/how-to-call-an-async-method-from-a-getter-or-setter — rdn87, Jan 07 '16 at 08:06
Possible duplicate of [How to call an async method from a getter or setter?](https://stackoverflow.com/questions/6602244/how-to-call-an-async-method-from-a-getter-or-setter) — Michael Freidgeim, Dec 10 '17 at 05:24

score 13 · Answer 1 · answered Jan 07 '16 at 08:04

13

You can't make async properties and you shouldn't want to - properties imply fast, non blocking operations. If you need to perform a long running activity, as implied by you're wanting to kick of an async operation and wait for it, don't make it a property at all.

Remove the setter and make a method instead.

answered Jan 07 '16 at 08:04

Damien_The_Unbeliever

234,701
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+1 more straight to the point. It is not supported in C#. Only methods, lambda expressions or anonymous methods can `await` – Leo Jan 07 '16 at 08:08
I completely agree with the point you're making. But isn't it still possible to use `Task.Wait()` in a property getter/setter? – Domysee Jan 07 '16 at 08:14
1

@Domysee - possible, yes. Advisable, no. – Damien_The_Unbeliever Jan 07 '16 at 08:14
7

@Damien_The_Unbeliever generally I agree with what you say about setters, but as usual, any general rule has exceptions. In this case, the MVVM pattern often requires doing async operations from setters since changing a property value of a VM object should be regarded as en Event. Getting around that often results in headaches, bugs and/or messy code when working with WPF. – Yuval Perelman Dec 11 '19 at 13:56
3

Any solution for when you have a databound setter, such as a filter field and you want to kickoff loading data into a collection async? – Arrow_Raider May 11 '20 at 20:55
1

@Damien_The_Unbeliever I have a wpf application where ActualPageNumber property is used with databinding. So when I change the property, the setter should access the db which can be slow. That is why I wanted an async setter, to keep the gui responsive. – Istvan Heckl Oct 02 '20 at 13:52

score -1 · Answer 2 · edited Jan 07 '16 at 08:29

-1

Use

public bool SomeMethod
{
  get { /* some code */ }
  set
  {
    AsyncMethod().Wait();
  }
}
public async Task AsyncMethod() {}

[EDIT]

edited Jan 07 '16 at 08:29

Ghasem

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answered Jan 07 '16 at 08:15

hubot

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18

Great idea to use `.Wait()` :) – Reiner Nov 15 '17 at 15:00
3

That `.Wait()` defeats the purpose of an `Asynchronous` methode – envyM6 Feb 05 '19 at 11:08
6

Even if it compiles, this approach could easily [result in a deadlock](https://stackoverflow.com/questions/13140523/await-vs-task-wait-deadlock). – John Wu Apr 11 '19 at 19:00

score -1 · Answer 3 · answered Jun 22 '20 at 22:06

-1

You can't use async function with property

Alternative Can use Result Property

public string UserInfo
{
    get => GetItemAsync().Result;
}

answered Jun 22 '20 at 22:06

Zanyar Jalal

1,407
12
29

Await an async function from setter property

3 Answers3

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