Data bound custom control with updating data when changed

Question

I have a question related to Data Binding

If we have class A with some property for example “UserName” and text control T1 bound as follow :

T1.DataBindings.Add("Text",A,"UserName",true,DataSourceUpdateMode.OnPropertyChanged);

I.e. property will be updated when user edit text

Now if instead of text box we have custom control C1 with control property “ControlProp” ( for example of type MyEnum ) and it is bound to class B with property MyProp of type MyEnum as following :

C1.DataBindings.Add("ControlProp ",B," MyProp",true,DataSourceUpdateMode.OnPropertyChanged);

The question is : how can be ensured behavior of custom control similar to text box described above , i.e. class B property will be updated when ControlProp changed ? Your help will be very valuable . Tnanks

Are you asking about the UC property or the class B property? — Henk Holterman
– Henk Holterman, Commented Mar 9, 2010 at 21:38
By other words my question : how can I ensure that with DataSourceUpdateMode.OnPropertyChanged custom control will behave similar to standard ( for example TextBox) control? — lm.
– lm., Commented Mar 9, 2010 at 22:16

Jerry · Accepted Answer · 2011-03-23 21:38:26Z

1

First, your class B have to implement INotifyPropertyChanged interface. This is the complete code or class B

public class ClassB : System.ComponentModel.INotifyPropertyChanged
{
    private string myprop;

    public string MyProp
    {
    get
    {
        return myprop;
    }
    set
    {
        if (value != myprop)
        {
        myprop = value;
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new System.ComponentModel.PropertyChangedEventArgs("MyProp"));
        }


        }


    }
    }

    #region INotifyPropertyChanged Members

    public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;

    #endregion

}

Then, suposse that your custom control have a label inside, and you want to bind the text of the label with your instance of class B. For example:

public partial class MyCustomControl : UserControl
{
    public MyCustomControl()
    {
        InitializeComponent();
    }

    public string MyCustomProperty
    {
        get
        {
            return label1.Text;
        }
        set
        {
            label1.Text = value;
        }
    }
}

If you bind the property MyProp of class B to MyCustomProperty of your custom control, when you change the property in your object, label1 should change its text.

    ClassB objectB = new ClassB();

    C1.DataBindings.Add("MyCustomProperty", objectB, "MyProp", true, DataSourceUpdateMode.OnPropertyChanged);

    objectB.MyProp = "Text 1";
    objectB.MyProp = "Text 2";

    // The final text is Text2

edited Mar 23, 2011 at 21:38

Jerry

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answered Mar 9, 2010 at 22:19

Javier

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2 Comments

lm. Over a year ago

Thanks for reply . What about opposite direction : for example custom control contains set of radio buttons bound to some field of enum type . How to ensure that underlying data will be updated before the control loses the focus ?

Javier Over a year ago

I´m trying but I doesn´t update the object field at right time... I´ll tell you if I figure out how...

lm. · Accepted Answer · 2010-03-11 07:06:44Z

0

I think I found the solution : Added Inotifypropertychange to the control definition : public partial class MyCustomControl : UserControl, INotifyPropertyChanged And in the controls property setter I raise the event ( as in Javier Morillo's example )

Thanks to all

answered Mar 11, 2010 at 7:06

lm.

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