C# WPF DataGrid 数据绑定时的单元格编辑类型模板

DataGrid的DataSource绑定的ObservableCollection<UserType>属性如果在运行中会发生变动，则不能在xaml手动定义Columns，否则当该属性发生变动时，UI不会随之更新，需要使用以下方法来实现单元格编辑类型的替换：

一、

设置DataGrid的AutoGenerateColumns为True，自动生成列的同时在AutoGeneratingColumn事件的方法将e.Column属性替换为DataGridTemplateColumn实例。

xaml:

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    <DataGrid ItemsSource="{Binding DgvItemSource}" AutoGenerateColumns="True" AutoGeneratingColumn="DataGridAutoGeneratingColumn" />

cs:

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      private void DataGridAutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
      {
          DataGrid dataGrid = sender as DataGrid;
          string columnName = e.PropertyName;
          DataGridTemplateColumn column = new DataGridTemplateColumn();
          e.Column = column;
          
      }

在定义的DataGridTemplateColumn实例的CellTemplate和CellEditingTemplate属性赋值新的DataTemplate实例，创建FrameworkElementFactory实例给DataTemplate实例的VisualTree赋值；FrameworkElementFactory实例可以使用SetBinding方法绑定数据源，使用SetValue方法指定模板，模板可定义在App.xaml里，通过Application.Current.FindResource方法获取。

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 DataGridTemplateColumn column = new DataGridTemplateColumn();
 DgvCellDataTemplateSelector cellTemplate = Application.Current.FindResource("DgvCellTemplateSelector") as DgvCellDataTemplateSelector;
 DgvCellDataTemplateSelector cellEditingTemplate = Application.Current.FindResource("DgvCellEditingTemplateSelector") as DgvCellDataTemplateSelector;
 
 column.Header = columnName;

 column.CellTemplate = new DataTemplate();
 FrameworkElementFactory factory = new FrameworkElementFactory(typeof(ContentPresenter));
 factory.SetBinding(ContentPresenter.ContentProperty, new Binding(columnName));
 factory.SetValue(ContentPresenter.ContentTemplateSelectorProperty, cellTemplate);
 column.CellTemplate.VisualTree = factory;

 column.CellEditingTemplate = new DataTemplate();
 FrameworkElementFactory editingfactory = new FrameworkElementFactory(typeof(ContentPresenter));
 editingfactory.SetBinding(ContentPresenter.ContentProperty, new Binding(columnName));
 editingfactory.SetValue(ContentPresenter.ContentTemplateSelectorProperty, cellEditingTemplate);
 column.CellEditingTemplate.VisualTree = editingfactory;

二、

编写模板选择器，DgvCellDataTemplateSelector是个实现了DataTemplateSelector接口的类型：

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public class TemplateMapping : List<TemplateMappingItem>
{

}

public class TemplateMappingItem
{
    public object Value { get; set; }
    public DataTemplate Template { get; set; }
}

public class DgvCellDataTemplateSelector : DataTemplateSelector
{
    public DataTemplate DefaultTemplate { get; set; }
    public TemplateMapping TemplateMap { get; set; }

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        if (item == null) return DefaultTemplate;
        if (item is DataBase data)
        {
            if (data == null) return DefaultTemplate;
            return TemplateMap?.Find(m => Equals(m.Value, data.dataType))?.Template ?? DefaultTemplate;
        }
        return DefaultTemplate;

    }
}

三、

定义模板和创建全局模板选择器实例，app.xaml:

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<Application x:Class="TestSystem.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:utilities="clr-namespace:TestSystem.Utilities"
             xmlns:ut="clr-namespace:TestSystem.UserType"
             StartupUri="View/MainWindow.xaml">
    <Application.Resources>
        <ResourceDictionary>

            <DataTemplate x:Key="TemplateDefault">
                <TextBlock Text="{Binding Data.Value}" />
            </DataTemplate>

            
            <utilities:TemplateMapping x:Key="DgvCellEditingDataTypeTemplateMap">
                <utilities:TemplateMappingItem 
            Value="{x:Static ut:ControlUserType+DataType.Readonly}" 
            Template="{StaticResource TemplateDefault}" />
            </utilities:TemplateMapping>
          

            <utilities:DgvCellDataTemplateSelector 
        x:Key="DgvCellEditingTemplateSelector"
        DefaultTemplate="{StaticResource TemplateDefault}"
        TemplateMap="{StaticResource DgvCellEditingDataTypeTemplateMap}" />

            

        </ResourceDictionary>
    </Application.Resources>
</Application>

四、

创建存放数据的UserType。

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  public enum DataType
  {
      Readonly
  }
  public abstract class DataBase : NotifyPropertyChanged,ICloneable
  {
      private object value;
      public DataType dataType;
      public object Value { get { return value; } set { this.value = value;OnPropertyChanged(nameof(Value)); } }

      public DataBase() { }

      public abstract object Clone();

  }
    public class ReadOnlyData : DataBase
   {
       public ReadOnlyData()
       {
           dataType = DataType.Readonly;
       }
       public override object Clone()
       {
           var clone = new ReadOnlyData
           {
               Value = this.Value
           };

           return clone;
       }
   }