WPF 数据网格列的默认值

Question

I have a DataGrid in my WPF application. I was wondering if there is a way to show default values for a column in the datagrid. For example, I let the user have the ability to add new rows to the DataGrid. Hence, at the bottom of the DataGrid, there is always a blank, empty row for the user to add data to. I was hoping to have a default value for a column in this row. Is there any way to achieve this functionality? Thanks!

Answer 1

Let's say ItemsSource of your DataGrid is a Collection of SomeClass and you are displaying different Properties of SomeClass in DataGrid Columns. What you can do is in constructor of default SomeClass assign the Properties some default value. In this way you can have default column value in DataGrid.

Edit

As you said the itemssource of column is a string there is one way I can think of..

Make it collection of SomeClass which will only have a string property. In the default constructor of SomeClass assign this string a default value. That default value will appear in your data grid column

Answer 2

Actually you can do this with the help of ValueConverters. When CanUserAddRows=True the DataContext of a row is binded to element of ItemsSource or to {DataGrid.NewItemPlaceholder} for the blank row.

    <DataGrid ItemsSource="{Binding Path=Collection}" CanUserAddRows=True >
        <DataGrid.Columns>
            <DataGridTemplateColumn>
                <DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding Converter={StaticResource ShowSuitablePart}}"/>
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate>
            </DataGridTemplateColumn>
        </DataGrid.Columns>
    </DataGrid>

And that's a code of ShowSuitablePart converter.

public class ShowSuitablePart : IValueConverter
    {
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value.ToString() == "{DataGrid.NewItemPlaceholder}")
            return "This is blank row, just click me to create a new one";
        else
            ((YourCollectionObject)value).SomeProperty;
    }
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new Exception();
    }
}

If you need TwoWay binding you'll have to use 2 elements in DataTemplate. One for the blank row, the second for regular rows with twoway binding. Set Visibility binding to hide the first element for regular rows and second element for blank row.

Remember if you determine Path to some property of you collection object it won't raise ValueConverter in blank row case.

Answer 3

Create a CheckBox column on DataGrind and bind it to "myBoolColumn"

<DataGridCheckBoxColumn Header="Selected" Binding="{Binding myBoolColumn}" />

DataTable data = new DataTable();
data.Columns.Add("myBoolColumn", typeof(System.Boolean));
data.Columns["myBoolColumn"].DefaultValue = false;