Question

我的WPF应用程序中有一个如下所示的数据网格。

<Window x:Class="MyApp.TestWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Grid>
    <DataGrid x:Name="dgTest"  ItemsSource="{Binding TestSource}" AutoGenerateColumns="False" >
            <DataGrid.Columns>
                <DataGridTemplateColumn Width="125" >
                       <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                                      <TextBox Text="{Binding Column1}"></TextBox>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
                <DataGridTemplateColumn Width="500" >
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <TextBox Text="{Binding Column2}"></TextBox>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>
         <Button Click="SaveButton_Click">Save</Button>
    </Grid>
</Window>

我使用以下代码绑定它。现在我的要求是当用户在datagrid中的这些文本框中输入一些文本并单击“保存”按钮时，它应该更新数据库。我怎样才能做到这一点？

namespace MyApp
{
    public partial class TestWindow: Window
    {
        private ObservableCollection<Test> _testSource
        public ObservableCollection<Test> TestSource
        {
            get
            {
                return _testSource;
            }
            set
            {
                _testSource = value;
                OnPropertyChanged("TestSource");
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propName));
            }
        }

        public TestWindow()
        {
            InitializeComponent();
            TestSource= new ObservableCollection<Test>();
             string strConnString = Application.Current.Properties["connectionStr"].ToString();
             SqlConnection con = new SqlConnection(strConnString);
            SqlCommand cmd = new SqlCommand("SELECT Column1,Column2 FROM MyTable", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dtTest = new DataTable();
            da.Fill(dtTest);
            foreach (DataRow row in dtTest)
            {
                Test cd = new Test();
                cd.Column1 = row["Column1"].ToString();
                cd.Column2 = row["Column2"].ToString();
                TestSource.Add(cd);
            }
            this.DataContext = this;
        }

        private void SaveButton_Click(object sender, RoutedEventArgs e)
        {
             // here I need to get the updated ObservableCollection, but now it is showing old data
             foreach Test t in TestSource)
            {
                string a = t.Column1;
                string b = t.Column2;
            }
        }
    }

    public class Test: 
    {
        public string Column1{ get; set; }
        public string Column2{ get; set; }
    }
}

由于

Answer 1

在DataGridTemplateColumn（或custom DataGrid.RowStyle中创建自己的用户界面时），DataGrid会更改所有绑定上的UpdateSourceTrigger（即应更新基础数据时）如果你自己没有指定它们，请Explicit。

那＆＃34;功能＆＃34;这里简要描述：5 Random Gotchas with the WPF DataGrid，尽管作者说无论你是否自己设置UpdateSourceTrigger都会发生这种情况，但自己设置确实有效（至少在.Net 4.0中）。

使用LostFocus来模仿默认的TextBox行为（以及PropertyChanged上的CheckBox等）：

...
<TextBox Text="{Binding Column1, UpdateSourceTrigger=LostFocus}"></TextBox>
...
<TextBox Text="{Binding Column2, UpdateSourceTrigger=LostFocus}"></TextBox>
...

Answer 2

我想提出几个附注 1）您不需要在TestSource属性上设置setter。您设置此值一次，并在设置DataContext之前，这是毫无意义的 2）你没有在Test类上实现INotifyPropertyChanged 3）您在UI线程上加载数据。这可能导致应用程序在加载数据时冻结（变得无响应）。

尝试将C＃代码更新为以下内容：

namespace MyApp
{
    public partial class TestWindow: Window
    {
        private ObservableCollection<Test> _testSource = new ObservableCollection<Test>();


        public TestWindow()
        {
            InitializeComponent();

            //NOTE: this blocks the UI thread. Slow DB/Network will freeze the App while we wait. 
            // This should be done on a background thread.
            string strConnString = Application.Current.Properties["connectionStr"].ToString();
            SqlConnection con = new SqlConnection(strConnString);
            SqlCommand cmd = new SqlCommand("SELECT Column1,Column2 FROM MyTable", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dtTest = new DataTable();
            da.Fill(dtTest);
            foreach (DataRow row in dtTest)
            {
                Test cd = new Test();
                cd.Column1 = row["Column1"].ToString();
                cd.Column2 = row["Column2"].ToString();
                TestSource.Add(cd);
            }
            this.DataContext = this;
        }

        public ObservableCollection<Test> TestSource { get { return _testSource; } }

        private void SaveButton_Click(object sender, RoutedEventArgs e)
        {
            var rowIdx = 0;
            foreach(var t in TestSource)
            {
                string a = t.Column1;
                string b = t.Column2;

                Console.WriteLine("Row {0}, col1='{1}', col2='{2}'", rowIdx++, a, b);
            }
        }
    }

    public sealed class Test : INotifyPropertyChanged
    {
        private string _column1;
        private string _column2;

        public string Column1
        { 
            get{return _column1;}
            set
            {
                if(_column1!=value)
                {
                    _column1 = value;
                    OnPropertyChanged("Column1");
                }
            }           
        }
        public string Column2
        { 
            get{return _column2;}
            set
            {
                if(_column2!=value)
                {
                    _column2 = value;
                    OnPropertyChanged("Column2");
                }
            }           
        }

        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propName)
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propName));
            }
        }
    }
}

您可能还想将Binding更新为twoway，但我认为这是默认设置。

<TextBox Text="{Binding Column1, Mode=TwoWay}" />

WPF中的DataGrid和Observable Collection

2 个答案: