IDXDataErrorInfo Interface

Provides methods to return error information for a business object’s properties.

Namespace: DevExpress.XtraEditors.DXErrorProvider

Assembly: DevExpress.Data.v19.2.dll

Declaration

C#

public interface IDXDataErrorInfo

VB.NET

Public Interface IDXDataErrorInfo

Remarks

A business object can implement the IDXDataErrorInfo interface to indicate if any property contains an invalid value, and as a result provide error information for these properties. Errors supplied via this interface are handled by a DXErrorProvider component. To track errors, the DXErrorProvider must be bound to the business object, or to a collection of business objects via the DXErrorProvider.DataSource property.

If a business object’s properties are edited in Developer Express editors (for example, a TextEdit, SpinEdit, etc) and errors are set via the IDXDataErrorInfo interface, the DXErrorProvider will track the errors and indicate them by displaying error icons within the editors. Hovering over the error icons displays the supplied error text.

Example

The following example demonstrates how to implement error notifications for a custom business object at the data source level, using the IDXDataErrorInfo interface. Error information will be handled by the DXErrorProvider component, which will indicate any error to an end-user.

In this example, the business object is represented by a custom MyRecord class. It contains two properties (FirstName and LastName) that cannot be empty. This class’ records are stored in a BindingSource component and edited using text editors (the FirstName and LastName properties are edited in a textEdit1 and textEdit2 controls respectively).

The requirement is to visually indicate errors within the editors, if the record’s FirstName or LastName property contain an empty string. In this example, the error information is provided on the data source level. The MyRecord class implements the IDXDataErrorInfo interface and returns the error information via the IDXDataErrorInfo.GetPropertyError method. To display the supplied errors within the editors, a DXErrorProvider component needs to be added to the form. It indicates errors as error icons, which can be hovered over to display error text.

To automatically track errors supplied by a data source, the DXErrorProvider component must be bound to this data source via the DXErrorProvider.DataSource property. In this example, the DXErrorProvider.DataSource property is set to the BindingSource.

The following image illustrates the resulting form after it has been opened at runtime. The editors contain empty strings, and as a result error icons are displayed within the editors:

C#

using DevExpress.XtraEditors.DXErrorProvider;

private void Form1_Load(object sender, EventArgs e) {
    // Specify the type of records stored in the BindingSource.
    bindingSource1.DataSource = typeof(MyRecord);
    // Create an empty MyRecord and add it to the BindingSource.
    MyRecord rec = new MyRecord();            
    rec.FirstName = "";
    rec.LastName = "";
    bindingSource1.Add(rec);
    // Bind the text editors to the MyRecord.FirstName and MyRecord.LastName properties.
    textEdit1.DataBindings.Add(new Binding("EditValue", this.bindingSource1, 
      "FirstName", true));
    textEdit2.DataBindings.Add(new Binding("EditValue", this.bindingSource1, 
       "LastName", true));
    // Bind the DXErrorProvider to the data source.
    dxErrorProvider1.DataSource = bindingSource1;
    // Specify the container of controls (textEdit1 and textEdit2) 
    // which are monitored for errors.
    dxErrorProvider1.ContainerControl = this;
}

//...
// A custom record class.
public class MyRecord : IDXDataErrorInfo {
    private string firstName;
    private string lastName;
    public MyRecord() { }
    public string FirstName {
        get { return firstName; }
        set { firstName = value; }
    }
    public string LastName {
        get { return lastName; }
        set { lastName = value; }
    }
    // Implements the IDXDataErrorInfo.GetPropertyError method.
    public void GetPropertyError(string propertyName, ErrorInfo info) {
        if (propertyName == "FirstName" && FirstName == "" ||
            propertyName == "LastName" && LastName == "") {
            info.ErrorText = String.Format("The '{0}' field cannot be empty", propertyName);
        }
    }
    // IDXDataErrorInfo.GetError method
    public void GetError(ErrorInfo info) { }        
}

VB.NET

Imports DevExpress.XtraEditors.DXErrorProvider

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) _
  Handles MyBase.Load
    ' Specify the type of records stored in the BindingSource.
    bindingSource1.DataSource = GetType(MyRecord)
    ' Create an empty MyRecord and add it to the BindingSource.
    Dim rec As MyRecord = New MyRecord
    rec.FirstName = ""
    rec.LastName = ""
    bindingSource1.Add(rec)
    ' Bind the text editors to the MyRecord.FirstName and MyRecord.LastName properties.
    TextEdit1.DataBindings.Add(New Binding("EditValue", Me.bindingSource1, _
      "FirstName", True))
    TextEdit2.DataBindings.Add(New Binding("EditValue", Me.bindingSource1, _
       "LastName", True))
    ' Bind the DXErrorProvider to the data source.
    DxErrorProvider1.DataSource = bindingSource1
    ' Specify the container of controls (textEdit1 and textEdit2) 
    ' which are monitored for errors.
    DxErrorProvider1.ContainerControl = Me
End Sub

'...
' A custom record class.
Public Class MyRecord
    Implements IDXDataErrorInfo

    Private _firstName As String
    Private _lastName As String
    Public Sub New()
        MyBase.New()
    End Sub
    Public Property FirstName() As String
        Get
            Return _firstName
        End Get
        Set(ByVal value As String)
            _firstName = value
        End Set
    End Property
    Public Property LastName() As String
        Get
            Return _lastName
        End Get
        Set(ByVal value As String)
            _lastName = value
        End Set
    End Property

    ' Implements the IDXDataErrorInfo.GetPropertyError method.
    Public Sub GetPropertyError(ByVal propertyName As String, ByVal info As ErrorInfo) _
      Implements IDXDataErrorInfo.GetPropertyError
        If ((propertyName = "FirstName" AndAlso FirstName = "") _
        OrElse (propertyName = "LastName" AndAlso LastName = "")) Then
            info.ErrorText = String.Format("The '{0}' field cannot be empty", propertyName)
        End If
    End Sub

    ' Implements the IDXDataErrorInfo.GetPropertyError method.
    Public Sub GetError(ByVal info As ErrorInfo) Implements IDXDataErrorInfo.GetError
    End Sub
End Class