Question

我想在组合框中显示“用户组”，并将选定的用户组键绑定到视图模型中的变量。我正在使用MVVM范例，我知道它非常接近工作，但我无法看到问题所在。通过Web调用登录后动态填充usergroups。我知道绑定工作正常，因为如果我删除xaml中的DisplayMemberPath属性，我会看到组。

我的班级用户组

public class UserGroup
{

    public long ugp_id;
    public String groupName;
    public float ugp_credits;
    public String logo;

    public UserGroup()
    {
    }
}

我有一个xaml

 ....
 <ComboBox  Grid.Row="0" Grid.Column="2" Height="30" VerticalAlignment="Top" Margin="0,4,0,0"
        ItemsSource="{Binding userGroupCollection, Mode=OneWay}"
        DisplayMemberPath="groupName"
        SelectedValue="{Binding SelectedUgpId}"
        SelectedValuePath="ugp_id" >

在我的ViewModel类中，我设置了一个可观察的集合：

  public ObservableCollection<UserGroup> _userGroupCollection;
  public ObservableCollection<UserGroup> userGroupCollection
    {
        get
        {
            return _userGroupCollection;
        }
        set
        {
            if (_userGroupCollection != value)
            {
                this._userGroupCollection = value;
                DynamicOnPropertyChanged();
            }
        }
    }

在网络电话会议之后，这些数据看起来像我期望的那样......

但是当我在查看页面时查看输出窗口时，我看到组合框条目是空白的（但显示了正确的数字）并且出现此错误：

'i3SoftClient.vshost.exe' (CLR v4.0.30319: i3SoftClient.vshost.exe): Loaded 'C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\PresentationFramework-SystemCore\v4.0_4.0.0.0__b77a5c561934e089\PresentationFramework-SystemCore.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
System.Windows.Data Error: 40 : BindingExpression path error: 'ugp_id' property not found on 'object' ''UserGroup' (HashCode=29245900)'. BindingExpression:Path=ugp_id; DataItem='UserGroup' (HashCode=29245900); target element is 'ComboBox' (Name=''); target property is 'NoTarget' (type 'Object')
System.Windows.Data Error: 40 : BindingExpression path error: 'groupName' property not found on 'object' ''UserGroup' (HashCode=29245900)'. BindingExpression:Path=groupName; DataItem='UserGroup' (HashCode=29245900); target element is 'ComboBox' (Name=''); target property is 'NoTarget' (type 'Object')
System.Windows.Data Error: 40 : BindingExpression path error: 'ugp_id' property not found on 'object' ''UserGroup' (HashCode=29245900)'. BindingExpression:Path=ugp_id; DataItem='UserGroup' (HashCode=29245900); target element is 'ComboBox' (Name=''); target property is 'NoTarget' (type 'Object')
System.Windows.Data Error: 40 : BindingExpression path error: 'ugp_id' property not found on 'object' ''UserGroup' (HashCode=29245900)'. BindingExpression:Path=ugp_id; DataItem='UserGroup' (HashCode=29245900); target element is 'ComboBox' (Name=''); target property is 'NoTarget' (type 'Object')
System.Windows.Data Error: 40 : BindingExpression path error: 'ugp_id' property not found on 'object' ''UserGroup' (HashCode=6695955)'. BindingExpression:Path=ugp_id; DataItem='UserGroup' (HashCode=6695955); target element is 'ComboBox' (Name=''); target property is 'NoTarget' (type 'Object')

我环顾四周，但我似乎无法理解错误信息。

Answer 1

你必须这样做：

public long ugp_id { get; set; }
public String groupName { get; set; }

立即重试：）

那些wernt属性的错误是什么，那些仅仅是变量:) 要使绑定适用于任何成员，您应该声明，如上所述：）

Answer 2

您不能将公共字段用于绑定。您必须使用属性

使用MVVM范例用c＃填充组合框

2 个答案: