CODEWITHSUNDEEP
c#xamarin.formsasync-await
DarkW1nter
DarkW1nter

Reputation: 2851

Get the result of an async task in C#, Xamarin Forms

I have the following lines of code which check if a device is registered in a database using an async method.

if (CrossConnectivity.Current.IsConnected)
{
      return await App._deviceService.GetDevice(id);
}

I had assumed that the await would have done just that - waited on GetDevice completing then return it's value, but on looking into I think that I need to use a callback if I want to get the actual result of the call so I can act upon it.

Can anyone tell me if I'm going down the correct route with this? Below is the called async task

public async Task<bool> GetDevice(string deviceID)
{
    string url = Resources.Urls.dev + Resources.DeviceApi.Get + "?id=" + deviceID;
    HttpResponseMessage result;
    result = await App.HttpClientInstance().GetAsync(url);

    if (result.StatusCode == System.Net.HttpStatusCode.OK)
    {
        return true;
    }
    return false;
}

Upvotes: 1

Views: 3463

Answers (2)

Martin Zikmund
Martin Zikmund

Reputation: 39072

No, actually using await on call of method defined like this (Task<bool>) means the caller will "wait" for the return value to be ready, so your return will either return true or false based on the result of GetDevice call.

Update: I am clarifying that the code does not actually actively wait for the method to complete, because that would defeat the purpose of the async/await combo, but I meant that the return statement will execute only after the method actually completes. While the HttpClient request runs, the calling thread is free to do other tasks in the meantime, which is the true advantage of using async/await.

Upvotes: 4

Camilo Terevinto
Camilo Terevinto

Reputation: 32068

return await App._deviceService.GetDevice(id);

This will return whatever GetDevice returns (true or false). You don't need to do anything further as you are already awaiting for the Task to complete.

A minor suggestion would be to change your GetDevice return to

return result.IsSuccessStatusCode;

So that you don't depend directly on 200 but rather 2xx (any success code).

Upvotes: 1

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