MVVM框架下，WPF实现Datagrid里的全选和选择

最近的一个项目是用MVVM实现，在实现功能的时候，就会有一些东西，和以前有很大的区别，项目中就用到了常用的序号，就是在Datagrid里的一个字段，用checkbox来实现。

既然是MVVM，就要用到ModleView，View和Model三层。

先看一下效果

当然，也可以确定是哪一项被选中了，这个代码里有。

实现这个全选功能，用到了三个DLL文件，分别为GalaSoft.MvvmLight.Extras.WPF4.dll，GalaSoft.MvvmLight.WPF4.dll，System.Windows.Interactivity.dll

Model曾需要实现INotifyPropertyChanged接口，以方便向客户端通知属性被更改了

public class MainModel:INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        private void INotifyPropertyChanged(string name)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(name));
            }
        }

        private int xh;

        public int Xh
        {
            get { return xh; }
            set { xh = value; }
        }

        private string name;

        public string Name
        {
            get { return name; }
            set { name = value;
            INotifyPropertyChanged("Name");
            }
        }

        private int age;

        public int Age
        {
            get { return age; }
            set { age = value;
            INotifyPropertyChanged("Age");
            }
        }

        private bool isSelected;

        public bool IsSelected
        {
            get { return isSelected; }
            set { isSelected = value;
            INotifyPropertyChanged("IsSelected");
            }
        }
    }

Model层里除了Datagrid里显示的序号，姓名和年龄意外，还有一个就是IsSelected，是用来确定是否选中的。

ViewModel层继承ViewModelBase，它来自GalaSoft.MvvmLight命名空间，重点是用到了里面的RaisePropertyChanged

全选的checkbox和下面选中的checkbox是分开来写的，各自有各自的Command，选中和不选中都有，IsSelectAll是用来标识是不是全选中

public class MainViewModel : ViewModelBase
    {
        public MainViewModel()
        {
            DataGridBaseInfo = AddDataGridInfo();
        }
        /// <summary>
        /// 给Datagrid绑定的属性
        /// </summary>
        private List<MainModel> dataGridBaseInfo;

        public List<MainModel> DataGridBaseInfo
        {
            get { return dataGridBaseInfo; }
            set
            {
                dataGridBaseInfo = value;
                RaisePropertyChanged("DataGridBaseInfo");
            }
        }
        /// <summary>
        /// 显示按钮
        /// </summary>
        private RelayCommand buttonCommand;

        public RelayCommand ButtonCommand
        {
            get
            {
                return buttonCommand ?? (buttonCommand = new RelayCommand(
                    () =>
                    {
                        int count = DataGridBaseInfo.ToList().FindAll(p => p.IsSelected == true).Count;
                        MessageBox.Show("选中了" + count + "项");
                        //for (int i = 0; i < count; i++)
                        //    MessageBox.Show(DataGridBaseInfo.ToList().FindAll(p=>p.IsSelected==true)[i].Name + "," + DataGridBaseInfo.ToList().FindAll(p=>p.IsSelected==true)[i].Age);
                    }));
            }            
        }

        public List<MainModel> AddDataGridInfo()
        {
            MainModel model;
            List<MainModel> list = new List<MainModel>();
            for (int i = 0; i < 5; i++)
            {
                model = new MainModel();
                model.Xh = i;
                model.Name = "李雷" + i;
                model.Age = 20 + i;
                list.Add(model);
            }
            return list;
        }
        /// <summary>
        /// 选中
        /// </summary>
        private RelayCommand selectCommand;

        public RelayCommand SelectCommand
        {
            get
            {
                return selectCommand ?? (selectCommand = new RelayCommand(
                    () =>
                    {
                        int selectCount = DataGridBaseInfo.ToList().Count(p => p.IsSelected == false);
                        if (selectCount.Equals(0))
                        {
                            IsSelectAll = true;
                        }
                    }));
            }
        }
        /// <summary>
        /// 取消选中
        /// </summary>
        private RelayCommand unSelectCommand;

        public RelayCommand UnSelectCommand
        {
            get
            {
                return unSelectCommand ?? (unSelectCommand = new RelayCommand(
                    () =>
                    {
                        IsSelectAll = false;
                    }));
            }
        }

        private bool isSelectAll = false;

        public bool IsSelectAll
        {
            get { return isSelectAll; }
            set
            {
                isSelectAll = value;
                RaisePropertyChanged("IsSelectAll");
            }
        }

        /// <summary>
        /// 选中全部
        /// </summary>
        private RelayCommand selectAllCommand;

        public RelayCommand SelectAllCommand
        {
            get
            {
                return selectAllCommand ?? (selectAllCommand = new RelayCommand(ExecuteSelectAllCommand, CanExecuteSelectAllCommand));
            }
        }

        private void ExecuteSelectAllCommand()
        {
            if (DataGridBaseInfo.Count < 1) return;
            DataGridBaseInfo.ToList().FindAll(p => p.IsSelected = true);
        }

        private bool CanExecuteSelectAllCommand()
        {
            if (DataGridBaseInfo != null)
            {
                return DataGridBaseInfo.Count > 0;
            }
            else
                return false;
        }

        /// <summary>
        /// 取消全部选中
        /// </summary>
        private RelayCommand unSelectAllCommand;

        public RelayCommand UnSelectAllCommand
        {
            get { return unSelectAllCommand ?? (unSelectAllCommand = new RelayCommand(ExecuteUnSelectAllCommand, CanExecuteUnSelectAllCommand)); }
        }

        private void ExecuteUnSelectAllCommand()
        {
            if (DataGridBaseInfo.Count < 1)
                return;
            if (DataGridBaseInfo.ToList().FindAll(p => p.IsSelected == false).Count != 0)
                IsSelectAll = false;
            else
                DataGridBaseInfo.ToList().FindAll(p => p.IsSelected = false);
        }

        private bool CanExecuteUnSelectAllCommand()
        {
            if (DataGridBaseInfo != null)
            {
                return DataGridBaseInfo.Count > 0;
            }
            else
            {
                return false;
            }
        }
    }

View层需要 xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" ，xmlns:Custom="http://www.galasoft.ch/mvvmlight" 两个命名空间

由于序号是绑定过来的，因此是用了stackpanel把checkbox和label放到了一起

<Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="20"/>
            <RowDefinition Height="*"/>
            <RowDefinition Height="20"/>
        </Grid.RowDefinitions>
        <DataGrid Grid.Row="1" ItemsSource="{Binding DataGridBaseInfo, Mode=TwoWay}" Margin="10" AutoGenerateColumns="False">
            <DataGrid.Columns>                
                <DataGridTemplateColumn>
                    <DataGridTemplateColumn.Header>
                        <CheckBox Content="全选" IsChecked="{Binding IsSelectAll,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}">
                            <i:Interaction.Triggers>                                
                                    <i:EventTrigger EventName="Checked">
                                        <Custom:EventToCommand Command="{Binding DataContext.SelectAllCommand, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" CommandParameter="{Binding IsSelectAll, ElementName=qx}"/>
                                    </i:EventTrigger>
                                    <i:EventTrigger EventName="Unchecked">
                                        <Custom:EventToCommand Command="{Binding DataContext.UnSelectAllCommand,  RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" CommandParameter="{Binding IsSelectAll, ElementName=qx}"/>
                                    </i:EventTrigger>                                
                            </i:Interaction.Triggers>
                        </CheckBox>
                    </DataGridTemplateColumn.Header>
                    <DataGridTemplateColumn.CellTemplate>                        
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
                                <CheckBox x:Name="cbXh"  VerticalAlignment="Center" IsChecked="{Binding IsSelected, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
                                    <i:Interaction.Triggers>
                                        <i:EventTrigger EventName="Checked">
                                            <Custom:EventToCommand Command="{Binding DataContext.SelectCommand, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" CommandParameter="{Binding IsChecked, ElementName=cbXh}"/>
                                        </i:EventTrigger>
                                        <i:EventTrigger EventName="Unchecked">
                                            <Custom:EventToCommand Command="{Binding DataContext.UnSelectCommand,  RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" CommandParameter="{Binding IsChecked, ElementName=cbXh}"/>
                                        </i:EventTrigger>
                                    </i:Interaction.Triggers>
                                </CheckBox>
                                <Label Content="{Binding Xh}" FontSize="14"/>
                            </StackPanel>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>                
                <DataGridTextColumn Header="姓名" Binding="{Binding Name}" Width="*"/>
                <DataGridTextColumn Header="年龄" Binding="{Binding Age}" Width="*"/>
            </DataGrid.Columns>            
        </DataGrid>
        <Button Content="显示" Grid.Row="2" Width="50" Command="{Binding ButtonCommand}"/>
    </Grid>

当时实现这个功能的时候也花了不少时间，希望给需要的人一点帮助。

代码