Posts Tagged ‘databinding’

Strongly typed databinding

Monday, March 23rd, 2009

Databinding proves to be very useful in some cases, but often turns out to be a maintenance nightmare. Since it requires strings with the property names to be passed as parameters of the Binding object. When the class, where a textbox is binded to, changes over time, so do property names. But since these property names are passed around as a string, they do not raise compile errors, causing unexpected behaviour of the application.

Here’s how you can make these bindings strongly typed, causing compilation errors if the property name of a class would change. Imagine we would like to bind a textbox to the Name property of the Person class, here’s the function that is going to help us. This function has a lambda expression returning a string and receiving a Person as parameter.

public string GetPropertyName(Expression<Func<Person, string>> propertySelector)
{
   MemberExpression memberExpression = propertySelector.Body as MemberExpression;
   MemberInfo propertyInfo = memberExpression.Member;
   return propertyInfo.Name;
}

The original binding code would like this, notice the “Name” string.

m_TextEditPerson.DataBindings.Add(new Binding("Text", m_Person, "Name"));

Here’s the new binding statement.

m_TextEditPerson.DataBindings.Add(new Binding("Text", m_Person, GetPropertyName(x => x.Name)));