如何防止在WPF中無故重繪ObservableCollection？

我有C# WPF專案，它將資料保存DataGrid到 SQL Server 資料庫中的表中

在資料庫中，我有兩個相互關聯的 表Factor和Commodity

ItemsSource由 an 填充的 DataGridObservableCollection命名WHOLE_DATA_FACTOR為來自FactorTable

并且ItemsSource在DataGridComboBoxColumn加載程式時僅填充一次，在我插入Factor表中RowEditEnding事件后，我想為 DataGrid 重新加載資料，

這些DataGridComboBoxColumn專案由 中的查詢填充一次SELECT CommodityCode, CommodityName FROM dbo.Commodity，但我注意到在 之后LoadDataAgian，集合中的專案開始重繪 （好像在每個專案上移動），這使程式變慢，并且DataGridComboBoxColumn ItemsSource開始填充再次，雖然我沒有那樣做

這是發生了什么的視頻：

mp4：https ://ufile.io/p5azjp40

完整的源代碼和資料庫： https ://ufile.io/uxneng9r

XAML：

        <DataGridComboBoxColumn Width="160" Header="DataGridComboBoxColumn"
                                SelectedValueBinding="{Binding CommodityID}" 
                                DisplayMemberPath="CommodityName" 
                                SelectedValuePath="CommodityCode"
                                >

            <DataGridComboBoxColumn.ElementStyle>
                <Style TargetType="{x:Type ComboBox}">
                    <Setter Property="ItemsSource" Value="{Binding Path=TheCommodityCombo_DATA, RelativeSource={RelativeSource AncestorType=Window}}" />


                </Style>
            </DataGridComboBoxColumn.ElementStyle>

            <DataGridComboBoxColumn.EditingElementStyle>
                <Style TargetType="{x:Type ComboBox}">
                    <Setter Property="ItemsSource" Value="{Binding Path=TheCommodityCombo_DATA, RelativeSource={RelativeSource AncestorType=Window}}" />

                    <Setter Property="IsEditable" Value="True"/>
                    <Setter Property="ScrollViewer.CanContentScroll" Value="True"/>
                    <Setter Property="VirtualizingStackPanel.IsVirtualizing" Value="True"/>
                    <Setter Property="VirtualizingStackPanel.VirtualizationMode" Value="Recycling"/>
                </Style>
            </DataGridComboBoxColumn.EditingElementStyle>
        </DataGridComboBoxColumn>

        <DataGridComboBoxColumn Width="200" Header="Status ComboBoxColumn"
                                SelectedValueBinding="{Binding STATUS}" 
                                DisplayMemberPath="STATUS_NAME" 
                                SelectedValuePath="STATUS">

            <DataGridComboBoxColumn.ElementStyle>
                <Style TargetType="{x:Type ComboBox}">
                    <Setter Property="ItemsSource" Value="{Binding Path=DataContext.STATUS_COMBO_DATA, RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />


                </Style>
            </DataGridComboBoxColumn.ElementStyle>

            <DataGridComboBoxColumn.EditingElementStyle>
                <Style TargetType="{x:Type ComboBox}">
                    <Setter Property="ItemsSource" Value="{Binding Path=DataContext.STATUS_COMBO_DATA, RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />

                    <Setter Property="IsEditable" Value="True"/>
                    <Setter Property="ScrollViewer.CanContentScroll" Value="True"/>
                    <Setter Property="VirtualizingStackPanel.IsVirtualizing" Value="True"/>
                    <Setter Property="VirtualizingStackPanel.VirtualizationMode" Value="Recycling"/>
                </Style>
            </DataGridComboBoxColumn.EditingElementStyle>
        </DataGridComboBoxColumn>


    </DataGrid.Columns>

</DataGrid>

代碼背后：

   public partial class MainWindow : Window
    {
        /// <summary>
        /// For Ensuring the new data is getting in Row end edit
        /// </summary>
        private bool _handle = true;
        MyerEntities dbms = new MyerEntities();


        #region Models and Collections
        /// <summary>
        /// For Factor Table
        /// </summary>
        public class MyCustomModel_Factor
        {
            public long? NUMBER { get; set; }
            public string CustomerName { get; set; }
            public long? CommodityID { get; set; }
            public long? STATUS { get; set; }
        }
        public ObservableCollection<MyCustomModel_Factor> WHOLE_DATA_FACTOR { get; set; } = new ObservableCollection<MyCustomModel_Factor>();

        /// <summary>
        /// For Commodity Table for ComboBox Items
        /// </summary>
        public ObservableCollection<MyCustomModel_Commodity> TheCommodityCombo_DATA { get; set; } = new ObservableCollection<MyCustomModel_Commodity>();
        public class MyCustomModel_Commodity
        {
            public long CommodityCode { get; set; }
            public string CommodityName { get; set; }
        }
        //STATUS
        public ObservableCollection<CutsomStatus_Model> STATUS_COMBO_DATA { get; set; } = new ObservableCollection<CutsomStatus_Model>();
        public class CutsomStatus_Model
        {
            public long? STATUS { get; set; }
            public string STATUS_NAME { get; set; }
        }
        #endregion


        public MainWindow()
        {
            InitializeComponent();
            DataContext = this;
        }
        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            //Filling DataGrid by ObservableCollection
            WHOLE_DATA_FACTOR.Clear();
            var RST = dbms.Database.SqlQuery<MyCustomModel_Factor>("SELECT * FROM Factor").ToList();
            foreach (var item in RST)
            { WHOLE_DATA_FACTOR.Add(item); }

            //Filling ComboBox from Another Table that Related to Factor Table
            TheCommodityCombo_DATA.Clear();
            var RST2 = dbms.Database.SqlQuery<MyCustomModel_Commodity>("SELECT CommodityCode, CommodityName FROM dbo.Commodity").ToList();
            foreach (var item2 in RST2)
            {
                TheCommodityCombo_DATA.Add(item2);
            }

            //STATUS Filling
            STATUS_COMBO_DATA.Add(new CutsomStatus_Model { STATUS = 1, STATUS_NAME = "Undone" });
            STATUS_COMBO_DATA.Add(new CutsomStatus_Model { STATUS = 2, STATUS_NAME = "Done" });
            STATUS_COMBO_DATA.Add(new CutsomStatus_Model { STATUS = 3, STATUS_NAME = "Canceled" });
        }

        private void MainDataGrid_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
        {
            try
            {
                var WhatWasRow = e.Row.Item as MyCustomModel_Factor;
                var TheCurrentColumnName = MainDataGrid.CurrentColumn.SortMemberPath;
                var test = WhatWasRow.GetType().GetProperty(TheCurrentColumnName).GetValue(WhatWasRow);

                var Editedrow = (e.EditingElement as ComboBox);

                var test3 = ((System.Windows.Controls.Primitives.Selector)e.EditingElement).SelectedValue;
            }
            catch (Exception)
            { goto one rrorResumeNext; }

        one rrorResumeNext:;
        }
        private void MainDataGrid_RowEditEnding(object sender, DataGridRowEditEndingEventArgs e)
        {
            if (_handle)
            {
                _handle = false;
                MainDataGrid.CommitEdit();
                var ROW_ITM = e.Row.Item as MyCustomModel_Factor;
                //...Do Insert 
                dbms.Database.ExecuteSqlCommand($"INSERT INTO dbo.Factor (CustomerName,CommodityID,STATUS) VALUES (N'{ROW_ITM.CustomerName}',{ROW_ITM.CommodityID},{ROW_ITM.STATUS})");


                //I think i need somthing like this ↓_________________________________
                //ObservableCollection.WHOLE_DATA_FACTOR.IsEnabled = false;
                //ObservableCollection.TheCommodityCombo_DATA.IsEnabled = false;
                //ObservableCollection.STATUS_COMBO_DATA.IsEnabled = false;

                LoadDataAgian();
                _handle = true;

                //ObservableCollection.WHOLE_DATA_FACTOR.IsEnabled = true;
                //ObservableCollection.TheCommodityCombo_DATA.IsEnabled = true;
                //ObservableCollection.STATUS_COMBO_DATA.IsEnabled = true;
                //_______________________________________________________________________
                return;
                //After this line , most stop continue ,
                //but it will go for → ObservableCollections property { get; set; } to refreshing every item , it feels Requery
            }
        }

        private void LoadDataAgian()
        {
            WHOLE_DATA_FACTOR.Clear();
            var RST = dbms.Database.SqlQuery<MyCustomModel_Factor>("SELECT * FROM Factor").ToList();
            foreach (var item in RST)
            { WHOLE_DATA_FACTOR.Add(item); }
        }
    }

相關鏈接： 在 WPF 中更新 ObservableCollection 會導致螢屏閃爍；我該如何預防？

我可以以某種方式暫時禁用 WPF 資料系結更改嗎？

更新： -ItemsSource的DatGrid從Factor表中填充 -ItemsSource的DataGridComboBoxColumn填充有Commoditiy

當我想重新加載 DataGrid 的資料時，"select * from Factor"我只重新加載了 DataGrid 的 ItemsSource 而不是 DataGridComboBoxColumn 的 ItemsSource 為什么 DataGridComboBoxColumn 的 ItemsSource 會重繪 （好像在每個專案上移動）

注意：如果解釋不好，請查看我的代碼中的視頻和評論

此致

uj5u.com熱心網友回復：

每當您修改（添加/洗掉） 時ObservableCollection，Target都會觸發 并開始呼叫{set; get;}集合專案的 getter 以更新自身。

如果此行為不能滿足您的需求，您可以執行以下操作：

1. 替換ObservableCollection為List。

2. 讓類實作INotifyPropertyChanged介面，如下所示（基于您的代碼）：

public partial class MainWindow : Window, INotifyPropertyChanged {
    // ..
    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
    // ..
}

3. 每當您想從代碼更新 UI 時，您都可以使用以下命令顯式執行此操作OnPropertyChanged：

private void Window_Loaded(object sender, RoutedEventArgs e)
{
    //Filling DataGrid by ObservableCollection
    WHOLE_DATA_FACTOR = new List<MyCustomModel_Commodity>();
    var RST = dbms.Database.SqlQuery<MyCustomModel_Factor>("SELECT * FROM Factor").ToList();
    foreach (var item in RST)
      WHOLE_DATA_FACTOR.Add(item);
    OnPropertyChanged(nameof(WHOLE_DATA_FACTOR));
    // ..
}

請注意，我創建了 a new List<MyCustomModel_Commodity>()，因此要更新Target 系結到 a List，您必須給它一個新的參考，您也可以WHOLE_DATA_FACTOR = WHOLE_DATA_FACTOR.ToList()在呼叫之前執行OnPropertyChanged

標籤：C＃ wpf xml 数据网格 可观察的集合

上一篇：C#正則運算式匹配

下一篇：C#中的結果HMACSHA256與VB.net不同