Advanced ASPX GridView Pagination and Data Entities

#region Copyright (c) 2010 Raul Iloc
/*
{***************************************************************************}
{                                                                           }
{       Copyright (c) 2010  RAUL ILOC (rauliloc@yahoo.com)                  }
{       ALL RIGHTS RESERVED                                                 }
{                                                                           }
{   THE WORK IS PROVIDED UNDER THE TERMS OF THIS CODE PROJECT OPEN LICENSE. }
{   THE WORK IS PROTECTED BY COPYRIGHT AND/OR OTHER APPLICABLE LAW.         }
{   ANY USE OF THE WORK OTHER THAN AS AUTHORIZED UNDER THIS LICENSE         }
{   OR COPYRIGHT LAW IS PROHIBITED.                                         }
{                                                                           }
{                                                                           }
{  BY EXERCISING ANY RIGHTS TO THE WORK PROVIDED HEREIN, YOU ACCEPT AND     }
{  AGREE TO BE BOUND BY THE TERMS OF THIS LICENSE. THE AUTHOR GRANTS YOU    }
{  THE RIGHTS CONTAINED HEREIN IN CONSIDERATION OF YOUR ACCEPTANCE OF SUCH  }
{  TERMS AND CONDITIONS. IF YOU DO NOT AGREE TO ACCEPT AND BE BOUND BY THE  }
{  TERMS OF THIS LICENSE, YOU CANNOT MAKE ANY USE OF THE WORK.              }
{                                                                           }
{***************************************************************************}
*/
#endregion Copyright (c) 2010 Raul Iloc

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
//
using Ra.GridView.Data;
using Ra.GridView.Util;
using Ra.GridView.Web.Data;

namespace Ra.GridView.Web
{
    /// <summary>
    /// Defines the contat list page.
    /// </summary>
    public partial class ContactListPage : BaseListPage
    {
        /// <summary>
        /// Gets the selected group ID from filter.
        /// </summary>
        public int GroupID
        {
            get
            {
                int groupID = 0;
                int.TryParse(_groupDropDownList.SelectedItem.Value, out groupID);
                //
                return groupID;
            }
        }

        /// <summary>
        /// Raises Init event used to associate this page with its data. 
        /// </summary>
        /// <param name="e">The arguments.</param>
        protected override void OnInit(EventArgs e)
        {
            //
            // ContactListPageData must be linked here with its page. 
            //
            ContactListPageData.Page = this;
            //
            base.OnInit(e);
        }

        /// <summary>
        /// Init event used to init the filter controls.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The arguments.</param>
        protected void Page_Init(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                try
                {
                    //
                    // Init the center drop down list used as filter control
                    //
                    List<Group> centerList = DataContext.Groups.ToList<Group>();
                    SortedDictionary<string, int> sortedData = new SortedDictionary<string, int>();
                    foreach (Group center in centerList)
                    {
                        if (!sortedData.ContainsValue(center.ID))
                            sortedData.Add(center.Name, center.ID);
                    }
                    //
                    _groupDropDownList.DataSource = sortedData;
                    _groupDropDownList.DataValueField = "value";
                    _groupDropDownList.DataTextField = "key";
                    _groupDropDownList.DataBind();
                    //
                    _groupDropDownList.Items.Insert(0, new ListItem("All Groups", "0"));
                    //
                    _groupDropDownList.SelectedIndex = 0;
                }
                catch (Exception ex)
                {
                    RaGridViewEventLog.LogException(ex);
                    this.ErrorMessage = "Error in loading the data from the database!";
                }
            }
        }

        /// <summary>
        /// Load event used to init the page.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The arguments.</param>
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
               try
                {
                    if (Request.QueryString["ContactID"] != null)
                    {
                        int ContactID;
                        int.TryParse(Request.QueryString["ContactID"], out ContactID);
                        ContactListPageData.ContactID = ContactID; // Search only one Contact!
                    }
                    else
                    {
                        ContactListPageData.ContactID = 0; // Allow to search by using filter!
                    }
                }
                catch (Exception ex)
                {
                    RaGridViewEventLog.LogException(ex);
                    this.ErrorMessage = "Error in loading the data from the database!";
                }
            }
        }

        /// <summary>
        /// Raised when a button is clicked in the GridView control.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The arguments.</param>
        protected void _contactsGridView_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            if (e.CommandName == "DeleteContact")
            {
                Contact contact = null;
                //
                try
                {
                    int contactID = Convert.ToInt32(e.CommandArgument);
                    //
                    contact = DataContext.Contacts.Single(item => item.ID == contactID);
                    contact.Deleted = true; //Mark as deleted!
                    //
                    DataContext.SaveChanges();
                    //
                    // Refresh the grid!
                    //
                    if (ContactListPageData.ContactID == 0)
                        RefreshGrid(true);
                    else
                        this.Response.Redirect("ContactListPage.aspx", false);
                }
                catch (Exception ex)
                {
                    RaGridViewEventLog.LogException(ex);
                    this.ErrorMessage = "Error in deleting the entity from the database!";
                }
            }
        }

        /// <summary>
        /// Refresh the grid.
        /// </summary>
        /// <param name="afterDelete">Must be true after delete operation.</param>
        private void RefreshGrid(bool afterDelete = false)
        {
            ContactListPageData.AfterDelete = afterDelete;
            _contactsGridView.DataBind();
        }

        /// <summary>
        /// _applyFilterButton Click event used to apply the fiter.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The arguments.</param>
        protected void _applyFilterButton_Click(object sender, EventArgs e)
        {
            //
            // Load data for new filter.
            // Note that the ContactID and NewFilter flags must be set before data binding!
            //
            ContactListPageData.ContactID = 0; 
            ContactListPageData.NewFilter = true;
            _contactsGridView.DataBind();
            _contactsGridView.PageIndex = 0;
        }

        /// <summary>
        /// _contactsGridView RowDataBound event used to link JavaScripts with link buttons.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The arguments.</param>
        protected void _contactsGridView_RowDataBound(object sender, GridViewRowEventArgs e)
        {
             if (e.Row.RowIndex < 0)
                return;
            //
            DataRow dataRow = ((DataRowView)e.Row.DataItem).Row;
            int userID = (int)dataRow["ID"];
            //
            ImageButton editLinkButton = (ImageButton)e.Row.FindControl("_editLinkButton");
            editLinkButton.Attributes.Add("onClick", "ShowEntityEditor('" + userID + "');return false;");
            //
            ImageButton addNewLinkButton = (ImageButton)e.Row.FindControl("_addNewLinkButton");
            addNewLinkButton.Attributes.Add("onClick", "ShowEntityEditor('0');return false;");
        }

        /// <summary>
        /// _refreshGridPopupButton Click used to refresh the grid.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The arguments.</param>
        protected void _refreshGridPopupButton_Click(object sender, EventArgs e)
        {
            if (Session["NewContactID"] != null)
            {
                int id = (int)Session["NewContactID"];
                Session["NewContactID"] = null;
                //
                // Show only the new created entity! 
                //
                ContactListPageData.ContactID = id; 
                _contactsGridView.DataBind();
            }
            else
            {
                //
                // Refresh the current page of the grid.
                //
                _contactsGridView.DataBind();
            }
        }

    }
}