DatagridComboBoxColumn不显示值

Question

I'm having some difficulty with the comboboxcolumn within a data grid, I want the value that's displayed and edited taken from the data object used by the rest of the data grid and the values for the drop down list taken from another data object. I've got the combobox dropdown list to work but I'm having difficulty getting it to show the value from the data grid row context.

Here's my layout

    <StackPanel Orientation="Horizontal">
        <Label>Sheet date:</Label>
        <DatePicker/>     
    </StackPanel>
    <DataGrid x:Name="gridTimesheets" Height="205" Margin="4, 4, 4, 0" AutoGenerateColumns="False" >
        <DataGrid.Columns>
            <DataGridTextColumn IsReadOnly="True" Header="No." Width="40" Binding="{Binding ItemNumber }"></DataGridTextColumn>

            <DataGridComboBoxColumn Width="120" Header="WorksorderID" x:Name="worksorderColumn"                       
            SelectedValueBinding="{Binding Path=WorksorderID}"  SelectedValuePath="WorksorderID"
             DisplayMemberPath="WONA">                   
            </DataGridComboBoxColumn>

            <DataGridTextColumn Header="Time On" Width="60" Binding="{Binding TimeOn}"></DataGridTextColumn>
            <DataGridTextColumn Header="Time Off" Width="60" Binding="{Binding TimeOff}"></DataGridTextColumn>
            <DataGridTextColumn IsReadOnly="True" Header="Duration" Width="65" Binding="{Binding Duration}"></DataGridTextColumn>
            <DataGridTemplateColumn>
                <DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                        <Button Content="Delete" x:Name="btnDelete"
                             Click="btnDelete_Click"></Button>
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate> 
            </DataGridTemplateColumn>

        </DataGrid.Columns>
    </DataGrid>
    <Button Content="Add" Margin="4, 4, 4, 0" Click="btnAdd_Click"></Button>
    <Button Content="Export" Margin="4, 4, 4, 4" ></Button>
</StackPanel>  

Here's my code

namespace Timesheet
{

public partial class MainWindow : Window
{

    TimesheetDatabase.TimesheetDB timesheetdb = new TimesheetDatabase.TimesheetDB();
    EFACSDatabase.EFACSDB efacsdb = new EFACSDatabase.EFACSDB();
    public MainWindow()
    {
        InitializeComponent();
        gridTimesheets.ItemsSource = timesheetdb.GetTimesheetItems();
        worksorderColumn.ItemsSource = efacsdb.GetOrderItems();

    }

OrderItem

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ComponentModel;

namespace EFACSDatabase
{
public class OrderItem : INotifyPropertyChanged
{
    private string orderid;
    public string OrderID
    {
        get { return orderid; }
        set
        {
            orderid = value;
            OnPropertyChanged(new PropertyChangedEventArgs("OrderID"));
        }
    }

    private string wona;
    public string WONA
    {
        get { return wona; }
        set
        {
            wona = value;
            OnPropertyChanged(new PropertyChangedEventArgs("WONA"));
        }
    }

    private string partid;

    public string PartID
    {
        get { return partid; }
        set
        {
            partid = value;
            OnPropertyChanged(new PropertyChangedEventArgs("PartID"));
        }
    }

    private string customer;
    public string Customer
    {
        get { return customer; }
        set
        {
            customer = value;
            OnPropertyChanged(new PropertyChangedEventArgs("Customer"));
        }
    }

    private string description;

    public string Description
    {
        get { return description; }
        set
        {
            description = value;
            OnPropertyChanged(new PropertyChangedEventArgs("Description"));
        }

    }

     public OrderItem(string orderid, string wona, string partid, string customer, string description)
    {
        OrderID = orderid;
        WONA = wona;
        PartID = partid;
        Customer = customer;
        Description = description;
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged(PropertyChangedEventArgs e)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, e);
    }
}
}

TimesheetItem

using System;
using System.Collections.Generic;
using System.Text;
using System.ComponentModel;

namespace TimesheetDatabase
{
public class TimesheetItem : INotifyPropertyChanged
{

    private int timesheetitemid;
    public int TimesheetItemID
    {
        get { return timesheetitemid; }
        set
        {
            timesheetitemid = value;
            OnPropertyChanged(new PropertyChangedEventArgs("TimesheetItemID"));
        }
    }

    private int timesheetid;
    public int TimesheetID
    {
        get { return timesheetid; }
        set
        {
            timesheetid = value;
            OnPropertyChanged(new PropertyChangedEventArgs("TimesheetID"));
        }
    }

    private int itemnumber;
    public int ItemNumber
    {
        get { return itemnumber; }
        set
        {
            itemnumber = value;
            OnPropertyChanged(new PropertyChangedEventArgs("ItemNumber"));
        }
    }



    private TimeSpan timeon;
    public TimeSpan TimeOn
    {
        get { return timeon; }
        set
        {
            timeon = value;
            OnPropertyChanged(new PropertyChangedEventArgs("TimeOn"));
        }
    }

    private TimeSpan timeoff;
    public TimeSpan TimeOff
    {
        get { return timeoff; }
        set
        {
            timeoff = value;
            OnPropertyChanged(new PropertyChangedEventArgs("TimeOff"));
        }
    }
    private String worksorderid;
    public String WorksorderID
    {
         get { return worksorderid; }
         set
         {
             worksorderid = value;
             OnPropertyChanged(new PropertyChangedEventArgs("WorksorderID"));
         }
     }


    private double duration;
    public double Duration
    {
        get { return duration; }
        set
        {
            duration = value;
            OnPropertyChanged(new PropertyChangedEventArgs("Duration"));
        }    
    }

    public TimesheetItem(int timesheetitemid, int timesheetid, int itemnumber, TimeSpan timeon, TimeSpan timeoff, String worksorderid, double duration)
    {
        TimesheetItemID = timesheetitemid;
        TimesheetID = timesheetid;
        ItemNumber = itemnumber;
        TimeOn = timeon;
        TimeOff = timeoff;
        WorksorderID = worksorderid;
        Duration = duration;
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged(PropertyChangedEventArgs e)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, e);
    }
}
}

I'm trying to get the combobox to display a value from GetTimesheetItems and allow the user to change that value from the drop down using values from GetOrderItems .

Answer 1

I think this is what you need:

<DataGridComboBoxColumn Width="120" 
                        Header="WorksorderID" 
                        x:Name="worksorderColumn"                       
                        SelectedValueBinding="{Binding Path=WorksorderID}"
                        SelectedValuePath="WONA"
                        DisplayMemberPath="WONA">                   
</DataGridComboBoxColumn>

• The SelectedValueBinding is bound to the WorksorderID property of the TimesheetItem object, which is the item of the DataGrid . This means that when you select one item from the combo, its value (determined by SelectedValuePath ) will be assigned to the WorksorderID property of the DataGrid item.
• The SelectedValuePath is set to the WONA property of the OrderItem object selected on the ComboBox . This indicates that the value of each item in the combo is determined by its WONA property, that according to you, corresponds to the WorksorderID...
• And similarly, the DisplayMemberPath is set to the WONA property of the OrderItem objects contained on the ComboBox drop-down list. This just selects the property you wish to visualize inside the combo, for each item.

EDIT: If you have problems with the combos being empty in the initial load, then invert the order on which you're loading the items. I mean, first load the items of the ComboBoxColumn, and then the items of the DataGrid.

public MainWindow()
{
    InitializeComponent();
    worksorderColumn.ItemsSource = efacsdb.GetOrderItems();
    gridTimesheets.ItemsSource = timesheetdb.GetTimesheetItems();
}