使用Id值绑定组合框名称 [英] Binding Combobox Name using Id value

问题描述

我有一个组合框控件。我从数据库中获取组合框值。我有Id和名字。但我只绑定在组合框中的名称。我想要的是，
1.如果我在Combobox中选择任何名称，我需要保存对应的ID在我的数据库。现在我可以绑定来自数据库的值和在Combobox中显示名称。但是当我在combobox中选择任何值并尝试保存方法时，它在ID上显示null值。这里是我的代码。请帮我找到一些解决方案。
Xaml：

I have a combobox control. I am getting combobox values from Database. There I have Id and Name. But I am binding only Name in the combobox. what i want is, 1. If I select any name in the Combobox, I need to save the Corresponding Id in my Database. Now I am able to bind the value from database and Display the Name in Combobox. but when I select any value in combobox and try to save means, it shows null value on the ID. Here is my code. Please help me to find some solution. Xaml:

    <ComboBox x:Name="cb_rentaltype" HorizontalAlignment="Left" Margin="150,5,0,0"    VerticalAlignment="Top" Height="35" Width="200"
                                          SelectedValue="{Binding MasterRentalType}"
                                          DisplayMemberPath="RentalTypeName"
                                          SelectedValuePath="RentalTypeId" />

我的代码背后：

        var status = new MasterRentalType();
        List<MasterRentalType> listRentalType =
                              status.Get<MasterRentalType>() as
                               List<MasterRentalType>;

        cb_rentaltype.ItemsSource = listRentalType;

，我想将Id绑定到数据上下文。这里是代码，

and i want to bind the Id to the Data context. here is the code,

 private void FacilityDataBind()
    {
        cb_rentaltype.DataContext = ??
    }

注意：MasterRentalType是我获取值的表。我有ID和名称值。

Note: MasterRentalType is the Table where i get the Values. There I have ID and Name values.

  public class MasterRentalType : EntityBase
     {
        public string RentalTypeId {get; set;}
        public string RentalTypeName {get; set;}       
     }

如何绑定和保存id值？ >

how can I bind and save the id value?

推荐答案

有几种方法可以实现这一点。其中一个实现如下：

There are several ways to achieve this. One of them is implemented below:

xaml应该如下所示：

The xaml should look like this:

<ComboBox x:Name="cb_rentaltype" HorizontalAlignment="Left" Margin="150,5,0,0" 
              ItemsSource="{Binding MasterRentalTypeColl, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
              SelectedItem="{Binding SelectedMasterRentalType, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
              DisplayMemberPath="RentalTypeName">            
    </ComboBox>

MasterRentalType class：

public class MasterRentalType : EntityBase, INotifyPropertyChanged 
{
    private string _RentalTypeId;
    private string _RentalTypeName;

    public string RentalTypeId
    {
        get { return _RentalTypeId; }
        set
        {
            _RentalTypeId = value;
            NotifyPropertyChanged("RentalTypeId");
        }
    }

    public string RentalTypeName
    {
        get { return _RentalTypeName; }
        set
        {
            _RentalTypeName = value;
            NotifyPropertyChanged("RentalTypeName");
        }
    }



    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged(String propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    #endregion
}

$ b b

模型类：

The model class:

public class MasterRentalModel: INotifyPropertyChanged 
{
    private MasterRentalType _SelectedMasterRentalType;
    private List<MasterRentalType> _MasterRentalTypeColl = new List<MasterRentalType>();

    public MasterRentalType SelectedMasterRentalType
    {
        get { return _SelectedMasterRentalType; }
        set
        {
            _SelectedMasterRentalType = value;
            NotifyPropertyChanged("SelectedMasterRentalType");
        }
    }

    public List<MasterRentalType> MasterRentalTypeColl
    {
        get { return _MasterRentalTypeColl; }
        set { _MasterRentalTypeColl = value; }
    }

    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged(String propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    #endregion
}

$ b b

在代码隐藏中，你只需要将模型分配给ComboBox的 DataContext 你可以实现这个任何其他函数（这里我已经在 Loaded 事件的窗口的事件处理程序中实现它） ：

And in the code-behind, you just need to assign the model to the DataContext of you ComboBox; you can implement this any other function (here I have implemented it in the event handler of Loaded event of my Window):

private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        MasterRentalModel masterRentalModel = new MasterRentalModel();

        // Fill the list of RentalType here
        masterRentalModel.MasterRentalTypeColl.Add(new MasterRentalType() { RentalTypeId = "1", RentalTypeName = "Monthly" });
        masterRentalModel.MasterRentalTypeColl.Add(new MasterRentalType() { RentalTypeId = "2", RentalTypeName = "Quarterly" });
        masterRentalModel.MasterRentalTypeColl.Add(new MasterRentalType() { RentalTypeId = "1", RentalTypeName = "Yearly" });

        cb_rentaltype.DataContext = masterRentalModel;
    }

每当用户更改选择时， SelectedMasterRentalType 将被更新。在 SelectedMasterRentalType 中，您可以获得 RentalTypeId 和 RentalTypeName 。如果你遵循正确的绑定，你的模型将总是更新;这是WPF的本质。

Whenever user changes the selection, SelectedMasterRentalType will be updated. And in the SelectedMasterRentalType, you can get both RentalTypeId and RentalTypeName. If you follow proper binding your model will always be updated; that's the essence of WPF.

希望这将有所帮助。

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