我正在尝试从ViewModel中的ComboBox
捕获所选项目的值。我确实得到了该值,但是由于某种原因,当我在IF语句中进行字符串比较以确定已选择了哪个项目时,该比较不起作用。
我想念什么?
这是在ViewModel中捕获值的正确方法吗?
<ComboBox x:Name="comboBox"
SelectedItem="{Binding SelectedItemInFilter, UpdateSourceTrigger=PropertyChanged}>
<ComboBoxItem IsSelected="True">No Selection</ComboBoxItem>
<ComboBoxItem>Car</ComboBoxItem>
<ComboBoxItem>Truck</ComboBoxItem>
</ComboBox>
public class MyViewModel : ViewModelBase{
public string _selectedItemInFilter;
public string SelectedItemInFilter
{
get { return _selectedItemInFilter; }
set {
if (_selectedItemInFilter != value) {
_selectedItemInFilter = value;
ComboBoxChanged();
Console.WriteLine("SelectedItem: {0}", SelectedItemInFilter); // outputs the right item name
RaisePropertyChanged();
}
}
}
private void ComboBoxChanged()
{
if (SelectedItemInFilter.ToString() == "Car") {
Console.WriteLine("Do something with car...");
}
else {
Console.WriteLine("Is not Car...");
}
}
}
答案 0 :(得分:2)
由于显式添加了ComboBoxItems(而不是将ItemsSource设置或绑定到字符串集合),所以SelectedItem也是ComboBoxItem,而不是字符串。但是,您可以使用Content
和SelectedValue
绑定到所选项目的SelectedValuePath
字符串:
<ComboBox SelectedValue="{Binding SelectedItemInFilter}"
SelectedValuePath="Content">
<ComboBoxItem>No Selection</ComboBoxItem>
<ComboBoxItem>Car</ComboBoxItem>
<ComboBoxItem>Truck</ComboBoxItem>
</ComboBox>
更简单的是根本不使用ComboBoxItems:
xmlns:sys="clr-namespace:System;assembly=mscorlib"
...
<ComboBox SelectedItem="{Binding SelectedItemInFilter}">
<sys:String>No Selection</sys:String>
<sys:String>Car</sys:String>
<sys:String>Truck</sys:String>
</ComboBox>
答案 1 :(得分:1)
您弄错了,因为项目不是真正的字符串,如果需要这样做,可以执行以下操作:
public object _selectedItemInFilter;
public object SelectedItemInFilter
{
get
{
return _selectedItemInFilter;
}
set
{
if (_selectedItemInFilter != value)
{
_selectedItemInFilter = value;
ComboBoxChanged();
Console.WriteLine("SelectedItem: {0}", SelectedItemInFilter); // outputs the right item name
NotifyPropertyChanged("SelectedItemInFilter");
}
}
}
private void ComboBoxChanged()
{
if (((ComboBoxItem)SelectedItemInFilter).Content.ToString() == "Car")
{
Console.WriteLine("Do something with car...");
}
else
{
Console.WriteLine("Is not Car...");
}
}
绑定ObservableCollection
不同于将项目声明到ComboBox
控件中。