Working with Dynamic Data Controls: Finding, Set Value, Get Value

Once you start working with ASP.NET, FormView, and the DynamicData controls you will soon learn that it isn’t as convenient to get and set values as you might like. You may also want to find controls not by their name, but by the column / property that they are bound to in the ADO.NET Entity Model.

I have put together some extensions to the Control class that make doing all these things much easier. All you have to do is create a class in your project called ControlExtensions. Copy and paste the code below into it. Change the namespace as needed. Then on the page you want to use it, just include the namespace. Then when you look at the methods on any control you will see the methods below. I have tested the code below with a FormView and also with DynamicControls on a User Control  that is then on a FormView. In both cases, the code works well.

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.DynamicData;
using System.ComponentModel;

namespace DistiPromo.Helpers
{
    public static class ControlExtensions
    {

        /// <summary>
        /// This will find the Dynamic Data control for the specified column (name from Entity model)
        /// </summary>
        /// <param name="control">the control (such as FormView or UserControl) that directly contains the control you are looking for</param>
        /// <param name="columnName">the name of the column (from the Entity Model) that you are looking for</param>
        /// <returns>The DynamicData Control for the column that you are looking for</returns>
        public static Control FindFieldTemplate(this Control control, string columnName)
        {
            // code copied from internal method: System.Web.DynamicData.DynamicControl.GetControlIDFromColumnName
            // Since it is internal, it could change, but I needed to get to it
            return control.FindControl("__" + columnName);
        }

        public static FieldTemplateUserControl FindFieldTemplateUserControl(this Control control, string columnName)
        {
            var userControl = ((FieldTemplateUserControl)(control.FindFieldTemplate(columnName)));
            if (userControl == null) throw new Exception("Could not find FieldTemplate in Control for " + columnName);
            return userControl;
        }

        public static Control FindControlForColumn(this Control control1, string columnName)
        {
            var control = FindFieldTemplateUserControl(control1, columnName).DataControl;
            if (control == null) throw new Exception("Could not find control in Control for " + columnName);
            return control;
        }

        public static T FindControlForColumn<T>(this Control control, string columnName) where T : Control
        {
            return FindControlForColumn(control, columnName) as T;
        }

        public static object GetValueForColumn(this Control control, string columnName)
        {
            var actualControl = FindFieldTemplateUserControl(control, columnName).DataControl;
            return GetValue(control, actualControl);
        }

        public static T GetValue<T>(this Control control, string columnName)
        {
            object rawVal = GetValueForColumn(control, columnName);
            //return (T)Convert.ChangeType(rawVal, typeof(T));

            // this is a little better because it handles nullable types also
            return (T)TypeDescriptor.GetConverter(typeof(T)).ConvertFrom(rawVal);
        }

        public static T GetValue<T>(this Control control1, Control control)
        {
            object rawVal = GetValue(control1, control);
            //return (T)Convert.ChangeType(rawVal, typeof(T));

            // this is a little better because it handles nullable types also
            return (T)TypeDescriptor.GetConverter(typeof(T)).ConvertFrom(rawVal);
        }

        public static object GetValue(this Control control, Control actualControl)
        {
            if (actualControl is ITextControl)
            {
                return (actualControl as ITextControl).Text;
            }
            else if (actualControl is ICheckBoxControl)
            {
                return (actualControl as ICheckBoxControl).Checked;
            }
            else if (actualControl is ListControl)
            {
                return (actualControl as ListControl).SelectedValue;
            }
            else if (actualControl is HiddenField)
            {
                return (actualControl as HiddenField).Value;
            }
            else throw new Exception("Could not get value of unknown control type: " + actualControl.GetType().ToString());

        }

        public static void SetValue(this Control control, string columnName, object value)
        {
            Control actualControl = FindControlForColumn(control, columnName);
            SetValue(control, actualControl, value);
        }

        public static void SetValue(this Control control, Control actualControl, object value)
        {

            if (actualControl is ITextControl)
            {
                (actualControl as ITextControl).Text = Convert.ToString(value);
            }
            else if (actualControl is ICheckBoxControl)
            {
                (actualControl as ICheckBoxControl).Checked = Convert.ToBoolean(value);
            }
            else if (actualControl is ListControl)
            {
                (actualControl as ListControl).SelectedValue = Convert.ToString(value);
            }
            else if (actualControl is HiddenField)
            {
                (actualControl as HiddenField).Value = Convert.ToString(value);
            }
            else throw new Exception("Could not set value of unknown control type: " + actualControl.GetType().ToString());
        }
    }
}