Question

I want to bind a textBox’s data to a Dictionary<string,string> entry. I am trying to achieve this through data binding, so the content get updated after the user edited the textBox.

This is a demo code of what I have done:

A classA that has a Name and List dictionary:

class ClassA
{
    public string Name { get; set; }
    public Dictionary<string, string> List { get; set; }

    public ClassA()
    {
        this.Name = "Hello";

        this.List = new Dictionary<string, string>
        {
            {"Item 1", "Content 1"},
            {"Item 2", "Content 2"}
        };
    }
}

In the Form, I bind textBox1 to Name and textBox2 to List["Item 1"]:

ClassA temp = new ClassA();

public Form1()
{
    InitializeComponent();

    textBox1.DataBindings.Add("Text", temp, "Name");
    textBox2.DataBindings.Add("Text", temp.List["Item 1"], "");

    label1.DataBindings.Add("Text", temp, "Name");
}

private void textBox2_TextChanged(object sender, EventArgs e)
{
    label1.Text = temp.List["Item 1"];
}

If I change textBox1 text, label1 content (Name) will successfully updated.

But if I change textBox2 text, label1 content will show the original List["Item 1"] value.

How can I bind textBox2 to List["Item 1"] correctly?

Answer 1

Use explicit binding and consume its events to achieve your goal

        Binding binding = new Binding("Text", temp, "List");
        binding.Parse += new ConvertEventHandler(binding_Parse);
        binding.Format += new ConvertEventHandler(binding_Format);
        textBox2.DataBindings.Add(binding); 

Parse event will occur when the value of a data-bound control changes.

    void binding_Parse(object sender, ConvertEventArgs e)
    {
        temp.List["Item 1"] = e.Value.ToString();
        label1.Text = temp.List["Item 1"]; 
    }

Format event will occur when the property of a control is bound to a data value.

    void binding_Format(object sender, ConvertEventArgs e)
    {
        if (e.Value is Dictionary<string, string>) 
        { 
            Dictionary<string, string> source = (Dictionary<string, string>)e.Value;
            e.Value = source["Item 1"];

        } 
    }