Question

I’m trying to clean up some pretty ugly form population code in the code behind of an aspx that looks like this:

SchoolCensus1.Checked = (bool)questions[0].SchoolCensus1;
SchoolCensus1Info.Text = questions[0].SchoolCensus1Info;
SchoolCensus2.Checked = (bool)questions[0].SchoolCensus2;
SchoolCensus2Info.Text = questions[0].SchoolCensus2Info;
SchoolCensus3.Checked = (bool)questions[0].SchoolCensus3;
SchoolCensus3Info.Text = questions[0].SchoolCensus3Info;

This goes on for quite a while.

What I have so far is this:

Type questionsType = questions[0].GetType();
PropertyInfo[] properties = questionsType.GetProperties();

        foreach (PropertyInfo property in properties)
        {
            if (property.PropertyType == typeof(Nullable<Boolean>))
            {
                CheckBox chkBox = container.FindControl(property.Name) as CheckBox;
                if (chkBox != null)
                    chkBox.Checked = (bool)property.GetValue(questions[0], null);
            }
            else if (property.PropertyType == typeof(String))
            {
                TextBox txtBox = container.FindControl(property.Name) as TextBox;
                if (txtBox != null)
                    txtBox.Text = (string)property.GetValue(questions[0], null);
            }
        }

This does what I need it to do, but I want to break out this part into a method to DRY it up a little more:

TextBox txtBox = container.FindControl(property.Name) as TextBox;
if (txtBox != null)
    txtBox.Text = (string)property.GetValue(questions[0], null);

Any advice as to the method needed to cope with the changing Control type? I’m guessing generics is what I need, but that really isn’t something I have much experience in.

Thanks in advance!

Answer 1

Be careful what you wish for…

No error control whatsoever, but here goes the generics version of your 2nd code block.

static class ControlAssign
{

    public static void Assign(Control target, object source, PropertyInfo prop)
    {
        Setters[prop.PropertyType](prop, source, target);
    }

    static ControlAssign()
    {
        Setters[typeof(string)] = (prop, src, target) =>
        {
            ((TextBox)target).Text =
                (string)prop.GetValue(src, null);
        };

        Setters[typeof(bool?)] = (prop, src, target) =>
        {
            ((CheckBox)target).Checked =
                (bool)prop.GetValue(src, null);
        };

        Setters[typeof(bool)] = (prop, src, target) =>
        {
            ((CheckBox)target).Checked =
                (bool)prop.GetValue(src, null);
        };
    }

    public delegate void Action<T, U, V>(T t, U u, V v);

    readonly static Dictionary<Type, Action<PropertyInfo, object, Control>> Setters = new Dictionary<Type, Action<PropertyInfo, object, Control>>();
}