C# - Binding TextBox to an integer

Question

How to bind a TextBox to an integer? For example, binding unit to textBox1.

public partial class Form1 : Form
{
    int unit;

    public Form1()
    {
        InitializeComponent();


    }

    private void Form1_Load(object sender, EventArgs e)
    {
        textBox1.DataBindings.Add("Text", unit, "???");
    }

Answer 1

One of the things I like to do is to create "presentation" layer for the form. It is in this layer that I declare the properties that are bound to the controls on the form. In this case, the control is a text box.

In this example I have a form with a textbox to display an IP Address

We now create the binding source through the textbox properties. Select DataBindings->Text. Click the down arrow; select 'Add Project Data Source'.

This starts up that Data Source wizard. Select Object. Hit 'Next'.

Now select the class that has the property that will be bounded to the text box. In this example, I chose PNetworkOptions. Select Finish to end the wizard. The BindingSource will not be created.

The next step is to select the actual property from the bound class. From DataBindings->Text, select the downarrow and select the property name that will be bound to the textbox.

In the class that has your property, INotifyPropertyChanged must implemented for 2-way communication for IP Address field

public class PNetworkOptions : IBaseInterface, INotifyPropertyChanged
{
    private string _IPAddress;


    private void NotifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }

    public string IPAddress
    {
        get { return _IPAddress; }
        set
        {
            if (value != null && value != _IPAddress)
            {
                _IPAddress = value;
                NotifyPropertyChanged("IPAddress");
            }
        }
    }
}

In the form constructor, we have to specifically define the binding

Binding IPAddressbinding = mskTxtIPAddress.DataBindings.Add("Text", _NetOptions, "IPAddress",true,DataSourceUpdateMode.OnPropertyChanged);

Answer 2

You can use a binding source (see comment). The simplest change is:

public partial class Form1 : Form
{
    public int Unit { get; set; }
    BindingSource form1BindingSource;

    private void Form1_Load (...)
    {
        form1BindingSource.DataSource = this;
        textBox1.DataBindings.Add ("Text", form1BindingSource, "Unit");
    }
}

However, you'll gain some conceptual clarity if you separate out the data a bit:

public partial class Form1 : Form
{
    class MyData {
        public int Unit { get; set; }
    }

    MyData form1Data;
    BindingSource form1BindingSource;

    private void Form1_Load (...)
    {
        form1BindingSource.DataSource = form1Data;
        textBox1.DataBindings.Add ("Text", form1BindingSource, "Unit");
    }
}

HTH. Note access modifiers omitted.

Answer 3

It would need to be a public property of an instance; in this case, the "this" would suffice:

public int Unit {get;set;}
private void Form1_Load(object sender, EventArgs e)
{
    textBox1.DataBindings.Add("Text", this, "Unit");
}

For two-way notification, you'll need either UnitChanged or INotifyPropertyChanged:

private int unit;
public event EventHandler UnitChanged; // or via the "Events" list
public int Unit {
    get {return unit;}
    set {
        if(value!=unit) {
            unit = value;
            EventHandler handler = UnitChanged;
            if(handler!=null) handler(this,EventArgs.Empty);
        }
    }
}

If you don't want it on the public API, you could wrap it in a hidden type somewhere:

class UnitWrapper {
    public int Unit {get;set;}
}
private UnitWrapper unit = new UnitWrapper();
private void Form1_Load(object sender, EventArgs e)
{
    textBox1.DataBindings.Add("Text", unit, "Unit");
}

For info, the "events list" stuff goes something like:

    private static readonly object UnitChangedKey = new object();
    public event EventHandler UnitChanged
    {
        add {Events.AddHandler(UnitChangedKey, value);}
        remove {Events.AddHandler(UnitChangedKey, value);}
    }
    ...
    EventHandler handler = (EventHandler)Events[UnitChangedKey];
    if (handler != null) handler(this, EventArgs.Empty);