如何使用绑定源判断用户是否修改了数据？

Question

我有一个绑定到绑定源的 DataGridView，该绑定源绑定到 List。用户单击一行，进入带有文本框等的表单。文本框是数据绑定的，如下所示：

if (txtID.DataBindings.Count == 0)
    txtID.DataBindings.Add("Text", bindingSource, "Title");

我希望能够检测用户在单击关闭按钮时是否修改了控件中的任何数据，以便我可以提示他们会说“您有未保存的工作。要保存吗？”

如何在绑定源上检测到这一点？

更新：我已经发现我可以执行bindingSource.EndEdit()，它将更改推送到列表中的项目。在我的项目中，我可以说如果 Dirty 抛出一个消息框，但如果他们单击“否”来保存信息，则 CancelEdit 将不起作用。

Answer 1

如果列表中的对象支持 INotifyPropertyChanged 事件，并将 List 替换为 BindingList您可以订阅 ListChanged 事件，用于获取用户所做的任何更改的通知。

Answer 2

如果您绑定到 DataSet 那么您很幸运：它有一个 HasChanges 属性。您可以通过对数据集调用 GetChanges 来获取实际更改。这将返回一个新数据集，其中包含所有更改行的副本

Answer 3

我现在做了这个功能。你可以这样使用：

if (changedOrNew(myBindingSource)){
    // Do something!
}

public bool changedOrNew(BindingSource bs){
    EntityObject obj = (EntityObject)bs.Current;
    if (obj==null)
        return false;
    return (obj.EntityState == EntityState.Detached ||
            obj.EntityState == EntityState.Added ||
            obj.EntityState == EntityState.Modified);
}

Answer 4

在尝试了不同的事情之后，我最终得到了这段代码：

private MyClass currentItem = null;
private bool itemDirty = false; // can be used for "do you want to save?"

private void bindingSource_CurrentChanged(object sender, EventArgs e)
{
    var handler = new PropertyChangedEventHandler((s, e2) => itemDirty = true);

    var crnt = currentItem as INotifyPropertyChanged;
    if(crnt != null) crnt.PropertyChanged -= handler;

    currentItem = (MyClass)bindingSource.Current;

    crnt = currentItem as INotifyPropertyChanged;
    if(crnt != null) crnt.PropertyChanged += handler;

    itemDirty = false;
}

尽管我在 Windows 窗体的实例字段中保存了大量状态信息，但它对我来说工作得很好。但是，使用 CurrentChanged 和 CurrentItemChanged 并没有帮助我。

Answer 5

一种更简单的方法是订阅 BindingSource 的 ListChanged 事件并根据事件类型设置 IsDirty 标志。

categoryBindingSource.ListChanged += 
new System.ComponentModel.ListChangedEventHandler(categoryBindingSource_ListChanged);

并在事件方法中设置 IsDirty = true...

void customerAccountBindingSource_ListChanged(object sender, system.ComponentModel.ListChangedEventArgs e)
{
    if (e.ListChangedType == System.ComponentModel.ListChangedType.ItemChanged)
        _isDirty = true;
}

这里需要注意的是，它无法检测修改后的值何时仍与原始值相同。如果需要该级别的准确性，可以另外使用 Memberwise.Clone。

Answer 6

我设置了一个相当简单的机制，如下所示：

1. 绑定控件后，我运行一个方法来查找所有绑定的
   控制并保存它们的当前值（我执行ReadValue()只是为了
   确保我已从字典中的数据源获取值
   将控件映射到其值（有一个小方法可以获取
   我拥有的每种控件的适当值）。
2. 我还为每个事件添加了一个更改事件处理程序（同样，具体的
   事件由控件类型决定，但它们都指向
   相同的处理程序）
3. 更改处理程序根据字典检查当前值
   价值。如果不同，那么它会相应地采取行动（在我的例子中
   将关闭按钮切换为取消按钮）。如果是一样的话
   它检查所有其他绑定控件，以便如果没有
   不同的是可以将取消切换回关闭；这是一个很好的功能
   当更改被撤消时它也可以识别这种方法，
   即使是通过重新输入原始值。
4. 在离开之前，如果有需要保存的更改，我会循环遍历
   再次绑定控件以执行 WriteValue()，以防万一 WinForms 没有执行
   抽出时间去传播一些改变。

如果有人感兴趣，我可以分享来源。

Answer 7

如果您的绑定源使用数据表，您可以这样做：

    public bool HasChanges()
    {
        bool Result = false;

        myBindingSource.EndEdit();
        Result = ((DataTable)myBindingSource.DataSource).GetChanges(DataRowState.Modified) != null;


        return Result;
    }

Answer 8

我知道这是一篇旧文章，但这里有一个带有 IsDirtyFlag 的扩展 BindingSource - 您可以按照自己的意愿调整它 - 我几年前从网络上的另一个帖子中提取了此代码 - 做了一些非常小的更改，我认为它最初是在VB - 我转换为 C# ..

using System.ComponentModel.Design;
using System.Windows.Forms;
using System.ComponentModel;
using System.Data;
using System;


public class BindingSourceExIsDirty : System.Windows.Forms.BindingSource, INotifyPropertyChanged
{

    #region "DECLARATIONS AND PROPERTIES"

    private string _displayMember;
    private DataTable _dataTable;
    private DataSet _dataSet;
    private BindingSource _parentBindingSource;
    private System.Windows.Forms.Form _form;
    private System.Windows.Forms.Control _usercontrol;




    private bool _isCurrentDirtyFlag = false;
    public bool IsCurrentDirty {
        get { return _isCurrentDirtyFlag; }
        set {
            if (_isCurrentDirtyFlag != value) {
                _isCurrentDirtyFlag = value;
                this.OnPropertyChanged(value.ToString());
                //call the event when flag is set
                if (value == true) {
                    OnCurrentIsDirty(new EventArgs());

                }
            }
        }
    }


    private string _objectSource;
    public string ObjectSource {
        get { return _objectSource; }
        set {
            _objectSource = value;
            this.OnPropertyChanged(value);
        }
    }


private bool _autoSaveFlag;

public bool AutoSave {
    get { return _autoSaveFlag; }
    set {
        _autoSaveFlag = value;
        this.OnPropertyChanged(value.ToString());
    }
} 

    #endregion

    #region "EVENTS"


    //Current Is Dirty Event
    public event CurrentIsDirtyEventHandler CurrentIsDirty;

    // Delegate declaration.
    public delegate void CurrentIsDirtyEventHandler(object sender, EventArgs e);

    protected virtual void OnCurrentIsDirty(EventArgs e)
    {
        if (CurrentIsDirty != null) {
            CurrentIsDirty(this, e);
        }
    }

    //PropertyChanged Event 
//  public event PropertyChangedEventHandler INotifyPropertyChanged.PropertyChanged;

    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string info)
    {

        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(info));
        }       

    }



    #endregion

    #region "METHODS"



    private void _BindingComplete(System.Object sender, System.Windows.Forms.BindingCompleteEventArgs e)
    {

        if (e.BindingCompleteContext == BindingCompleteContext.DataSourceUpdate) {

            if (e.BindingCompleteState == BindingCompleteState.Success & !e.Binding.Control.BindingContext.IsReadOnly) {
                //Make sure the data source value is refreshed (fixes problem mousing off control)
                e.Binding.ReadValue();
                //if not focused then not a user edit.
                if (!e.Binding.Control.Focused)
                    return;

                //check for the lookup type of combobox that changes position instead of value
                if (e.Binding.Control as ComboBox != null) {
                    //if the combo box has the same data member table as the binding source, ignore it
                    if (((ComboBox)e.Binding.Control).DataSource != null) {
                        if (((ComboBox)e.Binding.Control).DataSource as BindingSource != null) {
                            if (((BindingSource)((ComboBox)e.Binding.Control).DataSource).DataMember == (this.DataMember)) {
                                return;
                            }

                        }

                    }
                }
                IsCurrentDirty = true;
                //set the dirty flag because data was changed
            }
        }



    }

    private void _DataSourceChanged(System.Object sender, System.EventArgs e)
    {
        _parentBindingSource = null;
        if (this.DataSource == null) {
            _dataSet = null;
        } else {
            //get a reference to the dataset
            BindingSource bsTest = this;
            Type dsType = bsTest.DataSource.GetType();
            //try to cast the data source as a binding source
            while ((bsTest.DataSource as BindingSource != null)) {
                //set the parent binding source reference
                if (_parentBindingSource == null)
                    _parentBindingSource = bsTest;
                //if cast was successful, walk up the chain until dataset is reached
                bsTest = (BindingSource)bsTest.DataSource;
            }
            //since it is no longer a binding source, it must be a dataset or something else
            if (bsTest.DataSource as DataSet == null) {
                //Cast as dataset did not work

                if (dsType.IsClass == false) {
                    throw new ApplicationException("Invalid Binding Source ");
                } else {
                    _dataSet = null;

                }

            } else {
                _dataSet = (DataSet)bsTest.DataSource;
            }


            //is there a data member - find the datatable
            if (!string.IsNullOrEmpty(this.DataMember)) {
                _DataMemberChanged(sender, e);
            }
            //CType(value.GetService(GetType(IDesignerHost)), IDesignerHost)
            if (_form == null)
                GetFormInstance();
            if (_usercontrol == null)
                GetUserControlInstance();
        }
    }

    private void _DataMemberChanged(System.Object sender, System.EventArgs e)
    {
        if (string.IsNullOrEmpty(this.DataMember) | _dataSet == null) {
            _dataTable = null;
        } else {
            //check to see if the Data Member is the name of a table in the dataset
            if (_dataSet.Tables(this.DataMember) == null) {
                //it must be a relationship instead of a table
                System.Data.DataRelation rel = _dataSet.Relations(this.DataMember);
                if ((rel != null)) {
                    _dataTable = rel.ChildTable;
                } else {
                    throw new ApplicationException("Invalid Data Member");
                }
            } else {
                _dataTable = _dataSet.Tables(this.DataMember);
            }
        }
    }

    public override System.ComponentModel.ISite Site {
        get { return base.Site; }
        set {
            //runs at design time to initiate ContainerControl
            base.Site = value;
            if (value == null)
                return;
            // Requests an IDesignerHost service using Component.Site.GetService()
            IDesignerHost service = (IDesignerHost)value.GetService(typeof(IDesignerHost));
            if (service == null)
                return;
            if ((service.RootComponent as Form != null)) {
                _form = (Form)service.RootComponent;
            } else if ((service.RootComponent as UserControl != null)) {
                _usercontrol = (UserControl)service.RootComponent;
            }

        }
    }

    public System.Windows.Forms.Form GetFormInstance()
    {
        if (_form == null & this.CurrencyManager.Bindings.Count > 0) {
            _form = this.CurrencyManager.Bindings[0].Control.FindForm();

        }
        return _form;
    }

    /// <summary>
    /// Returns the First Instance of the specified User Control
    /// </summary>
    /// <returns>System.Windows.Forms.Control</returns>
    public System.Windows.Forms.Control GetUserControlInstance()
    {
        if (_usercontrol == null & this.CurrencyManager.Bindings.Count > 0) {
            System.Windows.Forms.Control[] _uControls = null;
            _uControls = this.CurrencyManager.Bindings[0].Control.FindForm().Controls.Find(this.Site.Name.ToString(), true);
            _usercontrol = _uControls[0];

        }
        return _usercontrol;
    }
    public BindingSourceExIsDirty()
    {
        DataMemberChanged += _DataMemberChanged;
        DataSourceChanged += _DataSourceChanged;
        BindingComplete += _BindingComplete;
    }

// PositionChanged
private override void _PositionChanged(object sender, EventArgs e)
{
    if (IsCurrentDirty) {
        // IsAutoSavingEvent
        if (AutoSave | MessageBox.Show(_msg, "Confirm Save", MessageBoxButtons.YesNo) == DialogResult.Yes) {
            try {
                //cast table as ITableUpdate to get the Update method
                //  CType(_dataTable, ITableUpdate).Update()
            } catch (Exception ex) {
                MessageBox.Show(ex, "Position Changed Error");
                // - needs to raise an event 
            }
        } else {
            this.CancelEdit();
            _dataTable.RejectChanges();
        }
        IsCurrentDirty = false;

    }
 base(e);
}


    #endregion

}

Answer 9

从我更新的问题中，我发现我必须使用 Memberwise.Clone 在 BeginEdit 中存储对象的当前版本，然后在 CancelEdit 中将其恢复到当前版本。

Answer 10

我总是做的是捕获控件的各个“更改”事件。在下面的示例中，我在本示例中使用了选项卡控件。 Try/Catch 是一个肮脏的解决方案，因为不必处理各种异常;-)

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    '
    ' some code        
    '
    BindingNavigatorSaveItem.Enabled = False
    For Each tabctl As Control In Me.TabControl1.Controls
        For Each ctl As Control In tabctl.Controls
            Try
                If ctl.GetType Is GetType(TextBox) Then
                    AddHandler DirectCast(ctl, TextBox).TextChanged, AddressOf GenDataChanged
                ElseIf ctl.GetType Is GetType(NumericUpDown) Then
                    AddHandler DirectCast(ctl, NumericUpDown).ValueChanged, AddressOf GenDataChanged
                ElseIf ctl.GetType Is GetType(ComboBox) Then
                    AddHandler DirectCast(ctl, ComboBox).SelectedValueChanged, AddressOf GenDataChanged
                ElseIf ctl.GetType Is GetType(CheckBox) Then
                    AddHandler DirectCast(ctl, CheckBox).CheckStateChanged, AddressOf GenDataChanged
                End If
            Catch ex As Exception
            End Try
        Next
    Next
End Sub

Private Sub GenDataChanged(sender As System.Object, e As System.EventArgs)
    BindingNavigatorSaveItem.Enabled = True
End Sub

Answer 11

我不确定在提出问题时它是否可用，但我使用 grid_CurrentCellDirtyStateChanged;事件

Answer 12

首先确保您设置了 DataSourceUpdateMode.OnPropertyChanged

txrFirstName.DataBindings.Add("Text", bindingSource1, "FirstName", false,DataSourceUpdateMode.OnPropertyChanged);

然后添加将此代码添加到您的 movenext 点击事件中

 if (((DataRowView)bindingSource1.Current).IsNew)
                {
                MessageBox.Show("Current Row IsNew");
                }
            if (((DataRowView)bindingSource1.CurrencyManager.Current).Row.HasVersion(DataRowVersion.Proposed))
                {
                MessageBox.Show("Current Row Modified");
                DialogResult dialogResult = MessageBox.Show("Current Row Modified", "Some Title", MessageBoxButtons.YesNo);
                if (dialogResult == DialogResult.Yes)
                    {
                    //do something
                    ((DataRowView)bindingSource1.CurrencyManager.Current).Row.AcceptChanges();
                    }
                else if (dialogResult == DialogResult.No)
                    {
                    //do something else
                    ((DataRowView)bindingSource1.CurrencyManager.Current).Row.RejectChanges();
                    }


                }
            else { 
                bindingSource1.MoveNext();
                }