Question

我的xamarin表单应用程序从我的Azure数据库中返回一个名为Users的可观察集合。返回后，它将清除ListView并将其替换为返回的json集合。

虽然它可以毫无问题地返回我的数据，但问题是它似乎只显示了最高级别的信息而没有进入id和FirstName。例如

Users.ReplaceRange(coffees);清除列表视图并输出返回的集合。什么是输出CoffeeCups.users我需要做的是显示FirstName，这是CoffeeCup.users的一层，例如

那么如何确保我的列表显示返回的json集合中的正确字段？

这里的参考是列表视图的代码。

CoffeesPage.xaml

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage 
    xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
    xmlns:local="clr-namespace:CoffeeCups;assembly=CoffeeCups"
    x:Class="CoffeeCups.CoffeesPage"
    Title="Cups Of Coffee">         
            <ListView 
                Grid.Row="1"                
                IsGroupingEnabled="true"
                HasUnevenRows ="true"
                ItemsSource="{Binding Users}"
                IsPullToRefreshEnabled="true"
                IsRefreshing="{Binding IsBusy, Mode=OneWay}"
                RefreshCommand="{Binding LoadCoffeesCommand}"
                x:Name="ListViewCoffees">
             <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <Label Text="{Binding FirstName}"/>    
                    </ViewCell>
                </DataTemplate>
             </ListView.ItemTemplate>
            </ListView>              
</ContentPage>

供参考：

users.cs

using System;

namespace CoffeeCups
{
    public class users
    {
        public string id { get; set; }
        public string FirstName { get; set; }
    }
}

AzureServices.cs

       public class AzureService
        {

            public MobileServiceClient Client { get; set; } = null;

            IMobileServiceSyncTable<users> userTable;

            public async Task Initialize()
            {
                var appUrl = "https://myurl.azurewebsites.net";

                //Create our client
                Client = new MobileServiceClient(appUrl);

                //InitialzeDatabase for path
                var path = "syncstore.db";
                path = Path.Combine(MobileServiceClient.DefaultDatabasePath, path);

                //setup our local sqlite store and intialize our table
                var store = new MobileServiceSQLiteStore(path);

                //Define table
                store.DefineTable<users>();

                //Initialize SyncContext
                await Client.SyncContext.InitializeAsync(store);

                //Get our sync table that will call out to azure
                userTable = Client.GetSyncTable<users>();
            }

            public async Task SyncCoffee()
            {
                try
                {
                    if (!CrossConnectivity.Current.IsConnected)
                        return;                   
                    await userTable.PullAsync("allUsers", userTable.CreateQuery());    
                    await Client.SyncContext.PushAsync();
                }
                catch (Exception ex)
                {
                    Debug.WriteLine("Unable to sync coffees, that is alright as we have offline capabilities: " + ex);
                }

            }

            public async Task<IEnumerable<users>> GetUsers()
            {
                //Initialize & Sync
                await Initialize();
                await SyncCoffee();

                return await userTable.OrderBy(c => c.FirstName).ToEnumerableAsync(); ;

            }
        }

CoffeesViewModel.cs

 async Task ExecuteLoadCoffeesCommandAsync()
        {
            try 
            {
                LoadingMessage = "Loading Coffees...";
                IsBusy = true;
                var coffees = await azureService.GetUsers();    
                Users.ReplaceRange(coffees);
            }
            catch (Exception ex) 
            {
                Debug.WriteLine("OH NO!" + ex);
                await Application.Current.MainPage.DisplayAlert("Sync Error", "Unable to sync coffees, you may be offline", "OK");
            } 
            finally 
            {
                IsBusy = false;
            }
        }

CoffeesPage.xaml.cs

protected override async void OnAppearing()
        {
            base.OnAppearing();
            if (vm.Users.Count == 0)
                vm.LoadCoffeesCommand.Execute(null);
            else
            {                 
                vm.LoadCoffeesCommand.Execute(null);
            }            
        }

Answer 1

我找到了答案，因为我怀疑它实际上非常简单。如果我们查看ListView，我们可以看到有一个名为IsGroupingEnabled的选项设置为True。

我现在知道这个选项实际上只是将任何返回的json集合组合成自己，有效地将结果捆绑到一个条目中，您可以公开与用户的交互。

将此选项切换为false（因为它不是我需要的东西）允许绑定的标签返回指定的内容。

如何指定要在我的Xamarain列表视图中显示的json字段？

1 个答案: