Binding custom properties' values of an instance of ExpandoObject to a .NET Windows Forms controls

Question

Context: Visual Studo 2012/C# 5.0

I have a .NET Windows Form with three textbox controls: firstNameTextBox, lastNameTextBox and ageTextBox, and a simple custom class

public class Customer
{
 public string FirstName { get; set; }
 public string LastName { get; set; }
 public int Age { get; set; }
}

and I'd like to bind the properties of an instance of Customer custom class to my Windows Forms controls. So I write:

private dynamic _customer;
private void Form_Load(object sender, EventArgs e)
{
 _customer = new Customer()
 {
 FirstName = "Andrew",
 LastName = "Chandler",
 Age = 23
 };
 this.firstNameTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", _customer, "FirstName"));
 this.lastNameTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", _customer, "LastName"));
 this.ageTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", _customer, "Age"));
}

and that works well. Then I slightly change the code by making it using an anonymous type:

private dynamic _customer;
private void Form_Load(object sender, EventArgs e)
{
 _customer = new 
 {
 FirstName = "Andrew",
 LastName = "Chandler",
 Age = 23
 };
 this.firstNameTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", _customer, "FirstName"));
 this.lastNameTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", _customer, "LastName"));
 this.ageTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", _customer, "Age"));

}

and that also works rather well, although in this case I do have only one-way binding. Then I change my code even more:

private dynamic _customer;
private void Form_Load(object sender, EventArgs e)
{ 
 _customer = new ExpandoObject();
 _customer.FirstName = "Andrew";
 _customer.LastName = "Chandler";
 _customer.Age = 23;
 this.firstNameTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", _customer, "FirstName"));
 this.lastNameTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", _customer, "LastName"));
 this.ageTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", _customer, "Age"));
}

and I'm getting runtime error:

'Cannot bind to the property or column FirstName on the DataSource. Parameter name: dataMember'

Question: How can I bind an instance of System.Dynamic.ExpandoObject (or System.Dynamic.DynamicObject) having a set of dynamic custom properties to a Windows Forms set of (textbox) controls?

Note 1: A solution with an aggregating/container helper class would be OK for me.

Note 2: I have spent a few hours googling and trying to apply different techniques (including the ones I have found here on StackOverflow) but I have failed.

Here is an 'Elegant' solution based on Hans Passant hint:

private dynamic _customer;
private void Form_Load(object sender, EventArgs e)
{
 _customer = new ExpandoObject();
 _customer.FirstName = "Andrew";
 _customer.LastName = "Chandler";
 _customer.Age = 23;
 bindExpandoField(this, "FirstNameTextBox", "Text", _customer, "FirstName");
 bindExpandoField(this, "lastNameTextBox", "Text", _customer, "LastName");
 bindExpandoField(this, "ageTextBox", "Text", _customer, "Age");
}
private void bindExpandoField(
 Control hostControl,
 string targetControlName,
 string targetPropertyName,
 dynamic expandoObject,
 string sourcePropertyName)
{
 Control targetControl = hostControl.Controls[targetControlName];
 var IDict = (IDictionary<string, object>)expandoObject;
 var bind = new Binding(targetPropertyName, expandoObject, null);
 bind.Format += (o, c) => c.Value = IDict[sourcePropertyName];
 bind.Parse += (o, c) => IDict[sourcePropertyName] = c.Value;
 targetControl.DataBindings.Add(bind);
}

Answer 1

Data binding uses Reflection, that works poorly on ExpandoObject since its "properties" are not actually properties on the underlying object. ExpandoObject implements IDictionary but that only binds easily on a list control, like ListBox.

It is not entirely impossible, you have to explicitly implement the Binding.Format and Parse events. Like this:

dynamic bag = new ExpandoObject();
bag.foo = "bar";
var bind = new Binding("Text", bag, null);
bind.Format += (o, c) => c.Value = bag.foo;
bind.Parse += (o, c) => bag.foo = c.Value;
textBox1.DataBindings.Add(bind);

That works, but of course doesn't score any elegance points.

• ShamilS: Actually your solution works well for me and it can be made elegant. Thanks a lot!
• ShamilS: Hans, I have just posted solution based on your hint above, in the bottom part of my question body text. Thank you.
• ShamilS: Hans, please have a look I have used your hint in C# 5.0 'Universal' WinForms TextBox Text 'Two-Way' Binder 'StackOverflow note'. Please comment on it if you find it interesting. Thank you.