消耗宁静的Web服务

Question

I am trying to consume an interface but I am having some difficulty here. I am trying to set it to a xamrin list view in behind a content page

public class xxxApiClient : IApi
 {
        readonly string url = "http://localhost:81/ ";
        readonly IHttpService httpService;

        public xxxApiClient(IHttpService httpService)
        {
            this.httpService = httpService;
        }

        public Task<List<JobsList>> GetJobs() => httpService.Get<List<JobsList>>($"{url}JobsLists");
}

How ever I am not to sure how I cosume getjobs correclty I am trying the following

public partial class JobsPage : ContentPage ,xxxWC.Interface.IApi
{
        public xxxWC.Interface.IApi api = new ful;

          public JobsPage ()
        {
            InitializeComponent ();
        }

        private Task SetItemSource()
    .   {
    .       JobListing.ItemsSource =   FuelAp
 }

How do I use the get jobs correctly above in the method setItemSource?.

The bit I am having hard time to understand is here.

How do I call the base GetJobs method I have already created in API Client.

      Task<List<JobsList>> IApi.GetJobs()
        {
            throw new NotImplementedException();
        }

        private Task SetItemSource()
     {
            JobListings.ItemsSource =await GetJobs();
    }
}

Edit 2 Ok based on suggestions below I updated My Code as such

    IHttpService httpService;
   xxxApiClient _api = newxxxApiClient(httpService);
      public JobsPage ()
    {
        InitializeComponent ();
    }

    private Task SetItemSource()
 {
        JobListings.ItemsSource =await GetJobs();
}

But i get the below error

Severity Code Description Project File Line Suppression State Error CS0236 A field initializer cannot reference the non-static field, method, or property 'JobsPage.httpService' xxxCallManagmentAppMobile C:\\Work\\xxxCallAppDev\\XamForms\\xxxCallManagmentApp\\xxxCallManagmentAppMobile\\FuelCallManagmentAppMobile\\Views\\JobsPage.xaml.cs 17 Active

Can someone explain why

Edit 3 Ok i got a bit further but still having some issues. as the main method is not awaited how do I call set SetItemSource.

xxxApiClient _api ;
      public JobsPage ()
    {
        InitializeComponent ()
            SetItemSource();

    }

    private async Task SetItemSource()
 {
        JobListings.ItemsSource = await client.GetJobs();
}

Answer 1

Assuming that IApi has been mapped to xxxApiClient implementation

Try resolving the service using the DependencyService so that it is available to be used in the view

public partial class JobsPage : ContentPage {
    public readonly IApi client;

    public JobsPage () {
        InitializeComponent ();
        client = DependencyService.Get<IApi>();
    }

    private async Task SetItemSource() {
        JobListing.ItemsSource = await client.GetJobs();
        //...
    }
}

As for calling the SetItemSource , it is async so should be awaited. That can't be done in the constructor.

Consider creating a event that can be raised and its handler used to await the desired behavior.

private event EventHandler loadingData = delegate { };
private async void onLoadingData(object sender, Eventargs args) {
    JobListing.ItemsSource =   await client.GetJobs();
}

Full code

public partial class JobsPage : ContentPage {
    public readonly IApi client;

    public JobsPage () {
        InitializeComponent ();
        //resolving client
        client = DependencyService.Get<IApi>();
        //subscribing to event 
        loadingData += onLoadingData;
        //raising event
        loadingData(this, EventArgs.Empty);
    }

    private async Task SetItemSource() {
        JobListing.ItemsSource = await client.GetJobs();
        //...
    }

    private event EventHandler loadingData = delegate { };
    private async void onLoadingData(object sender, Eventargs args) {
        JobListing.ItemsSource =   await client.GetJobs();
    }
}

Although a custom event was created, you could just as easily used on of the event/eventhandler of the view.

All of that code should actually live inside of a view model and then bound to the view in a binding context.