WinForm binding radio button

Question

I use VS2010 and then drag and drop Member datagridview to design view. After that I drag and drop name member textfield to design view and then try to edit and save. It's work properly.

And then I drag and drop sex radio button to design view. But binding it does't work.

How can I binding in this situation?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Test7
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void memberBindingNavigatorSaveItem_Click(object sender, EventArgs e)
        {
            this.Validate();
            this.memberBindingSource.EndEdit();
            this.tableAdapterManager.UpdateAll(this.dbDataSet);

        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'dbDataSet.Member' table. You can move, or remove it, as needed.
            this.memberTableAdapter.Fill(this.dbDataSet.Member);
            // TODO: This line of code loads data into the 'dbDataSet.Member' table. You can move, or remove it, as needed.
            this.memberTableAdapter.Fill(this.dbDataSet.Member);

        }


        private void memberBindingNavigatorSaveItem_Click_1(object sender, EventArgs e)
        {
            this.Validate();
            this.memberBindingSource.EndEdit();
            this.tableAdapterManager.UpdateAll(this.dbDataSet);

        }
    }
}

Answer 1

Here are two possible solutions.

---

Binding Format and Parse events

The Binding class has a built-in facility for on-the-fly transformations of bound data in the form of the Format and Parse events.

Here's how you would use those events with just the "Male" radiobutton. Create the binding in code, not in the designer:

// create binding between "Sex" property and RadioButton.Checked property
var maleBinding = new Binding("Checked", bindingSource1, "Sex");
// when Formatting (reading from datasource), return true for M, else false
maleBinding.Format += (s, args) => args.Value = ((string)args.Value) == "M";
// when Parsing (writing to datasource), return "M" for true, else "F"
maleBinding.Parse += (s, args) => args.Value = (bool)args.Value ? "M" : "F";
// add the binding
maleRb.DataBindings.Add(maleBinding);

// you don't need to bind the Female radiobutton, just make it do the opposite
// of Male by handling the CheckedChanged event on Male:
maleRb.CheckedChanged += (s, args) => femaleRb.Checked = !maleRb.Checked;

---

Computed Property

Another approach is to add a computed property to your datasource:

public bool IsMale
{ 
    get { return Sex == "M"; }
    set 
    {  
        if (value)
            Sex = "M";
        else
            Sex = "F";
    }
}

Now you can simply bind the Male radiobutton to this property on your datasource (just don't show this property in the grid).

And again you can hook up Female to Male like so:

maleRb.CheckedChanged += (s, args) => femaleRb.Checked = !maleRb.Checked;

Answer 2

While I realize this has already been answered, I thought I would provide an option that gives design time binding ability.

Make a new Custom RadioButton Object. This is done with the following code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace MSLabExample
{
    class RadioButtonBind : RadioButton
    {
        private string _selectValue = string.Empty;
        public string SelectValue
        {
            get { return _selectValue; }
            set
            {
                if (value == Text) Checked = true;
                else Checked = false;
                _selectValue = value;
            }
        }

        public RadioButtonBind()
        {
            this.CheckedChanged += new EventHandler(RadioButtonBind_CheckedChanged);
            this.TextChanged += new EventHandler(RadioButtonBind_TextChanged);

        }
        void RadioButtonBind_TextChanged(object sender, EventArgs e)
        {
            if (Checked) _selectValue = Text;
        }

        void RadioButtonBind_CheckedChanged(object sender, EventArgs e)
        {
            if (Checked) _selectValue = Text;
        }
    }
}

The basic concept of the above control is to use a string value that can be bound and will check itself if the bound string value is equal to the radio button text.

By using the radio button text, it allows easy understanding of the proper checked value, and also allows the SelectValue to be updated by simply changing the radio button text. No extra code is needed when modifying the radio button.

Now you simply bind the SelectedValue property for all radio buttons in the same group to some string property.

Limitations:

1. Two radio buttons in the same group cannot have the same text (but is this really a limitation?)
2. At design time, the checked values of the radio buttons may not appear accurate (i.e. two radio button in the same group may appear to be checked). This should not occur at runtime however.

Note when creating a custom control, the project must be built before the custom object is available in the toolbox.