.asp webform user control event

add control folder, add cousescontrol.ascx

add drop down list to cousescontrol.ascx

change auto post back to true in property window

//course control.ascx.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using Ctti.Data;

namespace CttiDemo.Controls

{

    public partial class CoursesControl : System.Web.UI.UserControl

    {

        //Step 3: define the public event

        public event CourseSelectionDelegate CourseSelect;

        private CTTIEntities1 DB = new CTTIEntities1();

        //Property returns the selected value of the DDL as an int instead of string

        public int SelectedId

        {

            get

            {

                return int.Parse(uxCourses.SelectedValue);

            }

        }

        protected void Page_Load(object sender, EventArgs e)

        {

            //populate the DDL

            if (!IsPostBack)

            {

                uxCourses.DataSource = DB.Courses.Select(c => new { Id = c.Id,

                                                         Name = c.CourseName }).ToList();

                uxCourses.DataTextField = "Name";

                uxCourses.DataValueField = "Id";

                uxCourses.DataBind();

                //raise the event first time page loads so event handler can load form

                uxCourses_SelectionChanged(this, null);

            }

        }

        protected void uxCourses_SelectionChanged(object sender, EventArgs args)

        {

            //Step 4: raise the event

            //if event is not raised, raise event

            if(CourseSelect != null)

            {

                //we need to get the course from the data layer using the id value from DDL

                int id = int.Parse(uxCourses.SelectedValue);

                Course crs = DB.Courses.Find(id);

                var c = new CourseEventArgs

                {

                    Id = crs.Id,

                    CourseCode = crs.CourseCode,

                    CourseName = crs.CourseName,

                    Description = crs.Description,

                    Duration = crs.Duration,

                    Fee = crs.Fee

                };

                //fire event everywhere 

                CourseSelect.Invoke(this, c);

            }

        }

    }

    //Step 1: define a custom event args class

    public class CourseEventArgs : EventArgs

    {

        public int Id { get; set; }

        public string CourseCode { get; set; }

        public string CourseName { get; set; }

        public decimal Fee { get; set; }

        public int Duration { get; set; }  

        public string Description { get; set; } 

    }

    //Step 2: define a delegate

    public delegate void CourseSelectionDelegate(object sender, CourseEventArgs args);

}

------------------------------------------------------------------

drag coursecontrol onto courses.aspx webform

//course.aspx.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace CttiDemo

{

    public partial class Courses : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

           //drop down list from coursecontrol.ascx fires event, courses.asp receives event

            uxCourses.CourseSelect += UxCourses_CourseSelect;            

        }

        //event handler

        private void UxCourses_CourseSelect(object sender, Controls.CourseEventArgs args)

        {

            uxName.Text = args.CourseName;

            uxCode.Text = args.CourseCode;

            uxFee.Text = args.Fee.ToString("c");

            uxDuration.Text = args.Duration.ToString() + " hrs";

            uxDescription.Text = args.Description;

        }

    }

}