更新：如果我使用"f40a0cad-608c-4190-a79e-47af918c087a"对Where过滤器进行硬编码，它会返回用户，看起来其他字符串字段（如Name或FacebookToken）即使在硬编码时也不起作用。
我正在使用 WindowsAzure.MobileServices 1.3.0-alpha3 和 WindowsAzure.MobileServices.SQLiteStore 1.0.0-alpha3
之前我已经多次这样做了没有任何问题，但是我遇到了一个奇怪的问题，当我知道它在表格中的事实时，我的过滤器没有返回任何内容。这是我的代码：
public async Task SyncUserAsync(string facebookToken)
{
await _userTable.PullAsync ();
var user = (await _userTable.Where(x => x.FacebookToken == facebookToken)
.Take (1)
.ToEnumerableAsync ())
.FirstOrDefault ();
var userTwo = await _userTable.LookupAsync ("f40a0cad-608c-4190-a79e-47af918c087a");
if (user != null)
Debug.WriteLine ("Facebook user {0} is synced", facebookToken);
}
此代码导致null user，但userTwo查找返回我正在寻找的用户。即使我从FacebookToken复制userTwo并对Where过滤器进行硬编码，也会返回null。
答案 0 :(得分：0)
LookupAsync方法根据对象的 id 进行查询。如果要使两个调用（ToEnumerable和Lookup）等效，则需要按如下方式重写它们：
public async Task SyncUserAsync(string facebookToken)
{
await _userTable.PullAsync ();
var facebookToken = "f40a0cad-608c-4190-a79e-47af918c087a";
var user = (await _userTable.Where(x => x.Id == facebookToken)
.Take (1)
.ToEnumerableAsync ())
.FirstOrDefault ();
var userTwo = await _userTable.LookupAsync (facebookToken);
if (user != null)
Debug.WriteLine ("Facebook user {0} is synced", facebookToken);
}
更新
这是一个complete, self-contained, small(-ish) example，它遵循您所拥有的具体情况：
使用Facebook身份验证配置的移动服务，带有一个表（用户），带有以下插入脚本：
function insert(item, user, request) {
item.facebookToken = user.userId;
request.execute();
}
Windows应用商店应用（也可能是其他平台）。添加了NuGet对最新版Azure Mobile Services SQLiteStore package（1.0.0-beta）的引用。
带有两个按钮的空白应用程序：
<Page
x:Class="App3.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:App3"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid.RowDefinitions>
<RowDefinition Height="100"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Button Name="btnPopulateRemote" Content="Populate remote table" Margin="10" FontSize="30"
HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
Click="btnPopulateRemote_Click"/>
<Button Name="btnPullAndSearch" Content="Pull and search locally" Margin="10" FontSize="30"
HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Grid.Column="1"
Click="btnPullAndSearch_Click"/>
<TextBox Name="txtDebug" AcceptsReturn="True" Margin="10" Grid.Row="1" Grid.ColumnSpan="2"/>
</Grid>
</Page>
using System;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.WindowsAzure.MobileServices;
using Microsoft.WindowsAzure.MobileServices.SQLiteStore;
using Newtonsoft.Json;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
namespace App3
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page
{
public static MobileServiceClient MobileService = new MobileServiceClient(
"https://MOBILE-SERVICE-NAME.azure-mobile.net/",
<<YOUR-APP-KEY-GOES-HERE>>
);
private const string TestId = "f40a0cad-608c-4190-a79e-47af918c087a";
private string facebookToken;
public MainPage()
{
this.InitializeComponent();
}
private async void btnPopulateRemote_Click(object sender, RoutedEventArgs e)
{
await InitializeIfNecessary();
Debug("Populating the remote table...");
try
{
var table = MobileService.GetTable<User>();
var user = new User
{
Id = "f40a0cad-608c-4190-a79e-47af918c087a",
Name = "John Doe"
};
await table.InsertAsync(user);
Debug("Inserted: {0}", user);
user = new User
{
Id = "01234567-89ab-cdef-0123-456789abcdef",
Name = "Jane Roe"
};
await table.InsertAsync(user);
Debug("Inserted: {0}", user);
}
catch (Exception ex)
{
TraceError(ex);
}
Debug("");
}
private void TraceError(Exception ex)
{
Debug("Error: {0} - {1}", ex.GetType().Name, ex.Message);
Exception inner = ex.InnerException;
while (inner != null)
{
Debug(" {0} - {1}", inner.GetType().Name, inner.Message);
inner = inner.InnerException;
}
}
private async Task InitializeIfNecessary()
{
if (MobileService.CurrentUser == null)
{
await MobileService.LoginAsync(MobileServiceAuthenticationProvider.Facebook);
Debug("Logged in as {0}", MobileService.CurrentUser.UserId);
this.facebookToken = MobileService.CurrentUser.UserId;
Debug("Using this value for the FacebookToken: {0}", this.facebookToken);
Debug("");
Debug("Creating the local store");
var store = new MobileServiceSQLiteStore("file.db");
store.DefineTable<User>();
await MobileService.SyncContext.InitializeAsync(store);
Debug("Initialized the sync context / local store");
Debug("");
}
}
private async void btnPullAndSearch_Click(object sender, RoutedEventArgs e)
{
await InitializeIfNecessary();
Debug("Pulling data locally and searching...");
try
{
var _usersTable = MobileService.GetSyncTable<User>();
await _usersTable.PullAsync();
Debug("Pulled data into local table");
var itemsInLocalTable = (await _usersTable.ReadAsync()).Count();
Debug("There are {0} items in the local table", itemsInLocalTable);
var user = (await _usersTable.Where(x => x.FacebookToken == facebookToken)
.Take(1)
.ToEnumerableAsync())
.FirstOrDefault();
Debug("User retrieved: {0}", user);
var userTwo = await _usersTable.LookupAsync(TestId);
Debug("User two: {0}", userTwo);
}
catch (Exception ex)
{
TraceError(ex);
}
Debug("");
}
private void Debug(string text, params object[] args)
{
if (args != null && args.Length > 0) text = string.Format(text, args);
this.txtDebug.Text = this.txtDebug.Text + text + Environment.NewLine;
}
}
public class User
{
[JsonProperty("id")]
public string Id { get; set; }
[JsonProperty("name")]
public string Name { get; set; }
[JsonProperty("facebookToken")]
public string FacebookToken { get; set; }
public override string ToString()
{
return string.Format("User[{0}, {1}, {2}]", Id, Name, FacebookToken);
}
}
}