WPF Combobox DisplayMemberPath

问题

Ok, I looked at other questions and didn't seem to get my answer so hopefully someone here can.

Very simple question why does the DisplayMemberPath property not bind to the item?

<ComboBox Grid.Row="1" Grid.Column="2" ItemsSource="{Binding PromptList}" DisplayMemberPath="{Binding Name}" SelectedItem="{Binding Prompt}"/>

The trace output shows that it is trying to bind to the class holding the IEnumerable not the actual item in the IEnumerable. I'm confused as to a simple way to fill a combobox without adding a bunch a lines in xaml.

It simply calls the ToString() for the object in itemssource. I have a work around which is this:

<ComboBox Grid.Row="1" Grid.Column="2" ItemsSource="{Binding PromptList}"  SelectedItem="{Binding Prompt}">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Name}"/>
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>

But in my opinion it's too much for such a simple task. Can I use a relativesource binding?

回答1:

DisplayMemberPath specifies the path to the display string property for each item. In your case, you'd set it to "Name", not "{Binding Name}".

回答2:

You are not binding to the data in the class, you are telling it to get it's data from the class member that is named by the member "name" so, if your instance has item.Name == "steve" it is trying to get the data from item.steve.

For this to work, you should remove the binding from the MemberPath. Change it to MemberPath = "Name" this tells it to get the data from the member "Name". That way it will call item.Name, not item.steve.

回答3:

You could remove DisplayMemberPath and then set the path in the TextBlock.
The DisplayMemberPath is really for when you have no ItemTemplate.
Or you could remove your ItemTemplate and use DisplayMemberPath - in which case it basically creates a TextBlock for you. Not recomended you do both.

   <TextBlock text="{Binding Path=Name, Mode=OneWay}"

回答4:

You should change the MemberPath="{Binding Name}" to MemberPath="Name". Then it will work.

回答5:

Alternatively you don't need to set the DisplayMemberPath. you can just include an override ToString() in your object that is in your PromptList. like this:

class Prompt {
    public string Name = "";
    public string Value = "";

    public override string ToString() {
        return Name;
    }
}

The ToString() will automatically be called and display the Name parameter from your class. this works for ComboBoxes, ListBoxes, etc.

来源：https://stackoverflow.com/questions/1460612/wpf-combobox-displaymemberpath

标签

wpf

combobox