Get and Set Properties using .NET Reflection

Introduction

I would like to set the text value on a textbox control. It sounds easy enough. First, I would like to create a textbox web control then I would like to access one of its properties “Text” and set the text to “Hello World”. Well what do you need to do to write your code in a generic way so you are can abstraction of the fact that the web control is actually a text box, it could be any web control.

We will visit different ways to be able to this.

Sample 1

Let’s start with the basics. I want to create a dynamic control a text box. Next, I need to set statically the Text property and as a last step the control is added to the control tree on the page.

On the mark up page we have a place holder control. We will add controls dynamically to the place holder.

<asp:PlaceHolder runat="server" ID="myPlaceHolder" />

On code-behind, we will define a method that will create our dynamic controls:

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
        _CreateDynamicTextBox ();
}
private void _CreateDynamicTextBox()
{
    TextBox ctrl = new TextBox();
    ctrl.ID = "DynamicTextBox";
    ctrl.EnableViewState = false;
    ctrl.Text = "Hello World";
    myPlaceHolder.Controls.Add(ctrl);
}

Sample 2

The next step is actually to use reflection to be able to set the value of the property dynamically. Make sure the namespace is added one your code-behind file

using System.Reflection;
...
private void _CreateDynamicTextBox()
{
    TextBox ctrl = new TextBox();
    ctrl.ID = "DynamicTextBox";
    ctrl.EnableViewState = false;
    PropertyInfo propertyBold = ctrl.GetType().GetProperty("Text",
    BindingFlags.Instance | BindingFlags.IgnoreCase | BindingFlags.Public);
    propertyBold.SetValue(ctrl, "Hello World", null);
    myPlaceHolder.Controls.Add(ctrl);
}

Sample 3

If we intend to update looping throw the properties then we could proceed as the following.

private void _CreateDynamicTextBox()
{
    TextBox ctrl = new TextBox();
    ctrl.ID = "DynamicTextBox";
    ctrl.EnableViewState = false;
    if (ctrl != null)
    {
        foreach (PropertyInfo property in ctrl.GetType().GetProperties())
        {
            if (property.CanWrite)
            {
                if (property.PropertyType == typeof(String))
                {
                    // Set properties on the dynamic control 
                    if (property.Name == "Text")
                        property.SetValue(ctrl, "Hello World", null);
                }
            }
        }
    }
    myPlaceHolder.Controls.Add(ctrl);
}

Conclusion

We learnt how to set dynamically properties using different techniques.

On our next chapter, we will learn how to set sub properties for example the Size property of a TextBox control has sub properties like Unit and UnitType classes.

If we also stress our attention to a technique I developed to set the FontInfo which is a sealed class. This will allow us to define properties like the font name, bold, underline, strikeout…

Thanks for reading. I hope that this article helped you out.

MSDN Reference

• Get Value: http://msdn.microsoft.com/en-us/library/system.reflection.propertyinfo.getvalue(VS.71).aspx
• Set Value: http://msdn.microsoft.com/en-us/library/aa330197(VS.71).aspx