wpf 使用 Id 值绑定组合框名称
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Binding Combobox Name using Id value
提问by JohnPaul
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:
我有一个组合框控件。我从数据库中获取组合框值。在那里我有 Id 和 Name。但我只绑定了组合框中的 Name。我想要的是， 1. 如果我在组合框中选择任何名称，我需要在我的数据库中保存相应的 Id。现在我可以绑定数据库中的值并在组合框中显示名称。但是当我在组合框中选择任何值并尝试保存手段时，它在 ID 上显示空值。这是我的代码。请帮我找到一些解决办法。Xml：
<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" />
My code Behind:
我的代码背后：
var status = new MasterRentalType();
List<MasterRentalType> listRentalType =
status.Get<MasterRentalType>() as
List<MasterRentalType>;
cb_rentaltype.ItemsSource = listRentalType;
and i want to bind the Id to the Data context. here is the code,
我想将 Id 绑定到数据上下文。这是代码，
private void FacilityDataBind()
{
cb_rentaltype.DataContext = ??
}
Note: MasterRentalType is the Table where i get the Values. There I have ID and Name values.
注意：MasterRentalType 是我获取值的表。在那里我有 ID 和 Name 值。
public class MasterRentalType : EntityBase
{
public string RentalTypeId {get; set;}
public string RentalTypeName {get; set;}
}
how can I bind and save the id value?
如何绑定和保存 id 值？
回答by Sheridan
Your problem is caused because you have data bound the ComboBox.SelectedValueproperty to your MasterRentalTypeproperty, which I assume is of type MasterRentalType, but then you set the SelectedValuePathproperty to RentalTypeId. So you're saying *make the SelectedValueuse the string RentalTypeIdproperty, but then data binding a MasterRentalTypeto it.
您的问题是因为您有数据将ComboBox.SelectedValue属性绑定到您的MasterRentalType属性，我认为它的类型是MasterRentalType，但随后您将该SelectedValuePath属性设置为RentalTypeId. 所以你是说 *make the SelectedValueusestring RentalTypeId属性，然后将数据绑定MasterRentalType到它。
There are a number of solutions. Correcting your example, you should try this:
有多种解决方案。纠正你的例子，你应该试试这个：
<ComboBox x:Name="cb_rentaltype" HorizontalAlignment="Left" Margin="150,5,0,0"
SelectedValue="{Binding MasterRentalType.RentalTypeId}"
DisplayMemberPath="RentalTypeName"
SelectedValuePath="RentalTypeId" />
Alternatively, you could have done this:
或者，您可以这样做：
<ComboBox x:Name="cb_rentaltype" HorizontalAlignment="Left" Margin="150,5,0,0"
SelectedItem="{Binding MasterRentalType}"
DisplayMemberPath="RentalTypeName" />
To find out more about the differences, please take a look at the How to: Use SelectedValue, SelectedValuePath, and SelectedItempage on MSDN.
要了解有关差异的更多信息，请查看MSDN上的如何：使用 SelectedValue、SelectedValuePath 和 SelectedItem页面。
回答by Debasis
There are several ways to achieve this. One of them is implemented below:
有几种方法可以实现这一点。其中之一在下面实现：
The xaml should look like this:
xaml 应如下所示：
<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>
The MasterRentalTypeclass:
本MasterRentalType类：
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
}
The model class:
模型类：
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
}
And in the code-behind, you just need to assign the model to the DataContextof you ComboBox; you can implement this any other function (here I have implemented it in the event handler of Loadedevent of my Window):
在代码隐藏中，您只需要将模型分配给DataContext您的 ComboBox；你可以实现这个任何其他功能（在这里我已经在事件处理程序实现了它Loaded我的情况下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;
}
Whenever user changes the selection, SelectedMasterRentalTypewill be updated. And in the SelectedMasterRentalType, you can get both RentalTypeIdand RentalTypeName. If you follow proper binding your model will always be updated; that's the essence of WPF.
每当用户更改选择时，SelectedMasterRentalType都会更新。在 中SelectedMasterRentalType，您可以同时获得RentalTypeId和RentalTypeName。如果您遵循正确的绑定，您的模型将始终更新；这就是 WPF 的本质。
Hope this will help.
希望这会有所帮助。
