WPF：绑定列表 <class> 到一个ComboBox

Question

I've been working on this problem for about 3 hours now, and I got to a dead end. Currently I'm trying to bind a list to a ComboBox.

I have used several methods to bind the List:

Code behind:

public partial class MainWindow : Window
{
    public coImportReader ir { get; set; }

    public MainWindow()
    {          
        ir = new coImportReader();
        InitializeComponent();
    }


    private void PremadeSearchPoints(coSearchPoint sp)
    {
        //SearchRefPoint.DataContext = ir.SearchPointCollection;
        SearchRefPoint.ItemsSource = ir.SearchPointCollection;
        SearchRefPoint.DisplayMemberPath = Name;

The data was binded correctly but the DisplayMemeberPath for some reason returned the name of the class and not the name of it's member.

The XAML method returned an empty string...

<ComboBox x:Name="SearchRefPoint" Height="30" Width="324" Margin="0,10,0,0"
          VerticalAlignment="Top" ItemsSource="{Binding ir.SearchPointCollection}"
          DisplayMemberPath="Name">

I've also tried to fill it with a new list which I create in the MainWindow. the result was the same in both cases.

Also I've tried to create and ListCollectionView which was success, but the problem was that I could get the index of the ComboBox item. I prefer to work by an Id. For that reason I was looking for a new solution which I found at: http://zamjad.wordpress.com/2012/08/15/multi-columns-combo-box/

The problem with this example is that is not clear how the itemsource is being binded.

Edit:

To sum things up: I'm currently trying to bind a list(SearchPointsCollection) of objects(coSearchPoints) defined in a class (coImportReader).

namespace Import_Rates_Manager
{
    public partial class MainWindow : Window
    {
        public coImportReader ir;
        public coViewerControles vc;
        public coSearchPoint sp;

        public MainWindow()
        {
            InitializeComponent();
            ir = new coImportReader();
            vc = new coViewerControles();
            sp = new coSearchPoint();
            SearchRefPoint.DataContext = ir;
        }
   }
}

//in function.... 

SearchRefPoint.ItemsSource = ir.SearchPointCollection;
SearchRefPoint.DisplayMemberPath = "Name";

namespace Import_Rates_Manager
{
    public class coImportReader
    {      
        public List<coSearchPoint> SearchPointCollection = new List<coSearchPoint>();
    }
}

namespace Import_Rates_Manager
{
    public class coSearchPoint
    {
        public coSearchPoint()
        {
            string Name = "";
            Guid Id = Guid.NewGuid();
            IRange FoundCell = null;

        }
    }
}

This results in a filled combobox with no text

Answer 1

The Collection you are binding to needs to be a property of ir not a field.

Also try this :

public coImportReader ir { get; set; } 
public <type of SearchPointCollection> irCollection { get { return ir != null ? ir.SearchPointCollection : null; } }

Bind to irCollection and see what errors you get if any.

Answer 2

Here a simple example using the MVVM Pattern

XAML

<Window x:Class="Binding_a_List_to_a_ComboBox.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
<Grid HorizontalAlignment="Left"
      VerticalAlignment="Top">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="150"/>
        <ColumnDefinition Width="Auto"/>
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition Height="50"/>
        <RowDefinition Height="25"/>
    </Grid.RowDefinitions>

    <ComboBox Grid.Column="0" Grid.Row="0" ItemsSource="{Binding SearchPointCollection , UpdateSourceTrigger=PropertyChanged}"
              SelectedIndex="{Binding MySelectedIndex, UpdateSourceTrigger=PropertyChanged}"
              SelectedItem="{Binding MySelectedItem, UpdateSourceTrigger=PropertyChanged}">
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition/>
                        <RowDefinition/>
                        <RowDefinition/>
                    </Grid.RowDefinitions>
                    <TextBlock Text="{Binding Id}" Grid.Row="0"/>
                    <TextBlock Text="{Binding Name}" Grid.Row="1"/>
                    <TextBlock Text="{Binding Otherstuff}" Grid.Row="2"/>
                </Grid>
            </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>
    <Button Content="Bind NOW" Grid.Column="0" Grid.Row="1" Click="Button_Click"/>
    <TextBlock Text="{Binding MySelectedIndex, UpdateSourceTrigger=PropertyChanged}" Grid.Column="1" Grid.Row="0"/>

    <Grid  Grid.Column="1" Grid.Row="1"
           DataContext="{Binding MySelectedItem, UpdateSourceTrigger=PropertyChanged}">
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>

        <TextBlock Text="{Binding Id}" Grid.Column="0"/>
        <TextBlock Text="{Binding Name}" Grid.Column="1"/>
        <TextBlock Text="{Binding SomeValue}" Grid.Column="2"/>
    </Grid>
</Grid>

Code

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows;
using Import_Rates_Manager;

namespace Binding_a_List_to_a_ComboBox
{
    /// <summary>
    /// Interaktionslogik für MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            DataContext = new coImportReader();
        }    
    }
}
namespace Import_Rates_Manager
{
    public class coImportReader : INotifyPropertyChanged
    {
        private List<coSearchPoint> myItemsSource;
        private int mySelectedIndex;
        private coSearchPoint mySelectedItem;

        public List<coSearchPoint> SearchPointCollection 
        {
            get { return myItemsSource; }
            set
            {
                myItemsSource = value;
                OnPropertyChanged("SearchPointCollection ");
            }
        }

        public int MySelectedIndex
        {
            get { return mySelectedIndex; }
            set
            {
                mySelectedIndex = value;
                OnPropertyChanged("MySelectedIndex");
            }
        }

        public coSearchPoint MySelectedItem
        {
            get { return mySelectedItem; }
            set { mySelectedItem = value;
            OnPropertyChanged("MySelectedItem");
            }
        }

        #region cTor

        public coImportReader()
        {
            myItemsSource = new List<coSearchPoint>();
            myItemsSource.Add(new coSearchPoint { Name = "Name1" });
            myItemsSource.Add(new coSearchPoint { Name = "Name2" });
            myItemsSource.Add(new coSearchPoint { Name = "Name3" });
            myItemsSource.Add(new coSearchPoint { Name = "Name4" });
            myItemsSource.Add(new coSearchPoint { Name = "Name5" });
        }
        #endregion

        #region INotifyPropertyChanged Member

        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void OnPropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
        }

        #endregion
    }

    public class coSearchPoint
    {
        public Guid Id { get; set; }
        public String Name { get; set; }
        public IRange FoundCell { get; set; }    

        public coSearchPoint()
        {
            Name = "";
            Id = Guid.NewGuid();
            FoundCell = null;    
        }
    }

    public interface IRange
    {
        string SomeValue { get; }
    }
}

Here are 3 Classes:

• MainWindow which set VM as his Datacontext
• coImportReader the Class which presents your properties for your bindings
• coSearchPoint which is just a Container for your information
• IRange which is just an Interface

Answer 3

The DisplayMemberPath should contain the property name of the elements in your collection. Assuming the elements in the SearchPointCollection are of the type SearchPoint and this class has a Property SearchPointName you should set DisplayMemberPath like this:

SearchRefPoint.DisplayMemberPath = "SearchPointName";

Edit:

In your code the class coSearchPoint has the Field Name defined in the Constructor. Name has to be a Property of the class, otherwise the Binding can't work.