PagedList.cs :  » Bloggers » Mayando » JelleDruyts » Web » Mvc » Paging » C# / CSharp Open Source

using System;
using System.Collections.Generic;
using System.Linq;

namespace JelleDruyts.Web.Mvc.Paging{
    /// <summary>
    /// A list that allows paging.
    /// </summary>
    /// <typeparam name="T">The type of the items in the list.</typeparam>
    /// <remarks>
    /// Adapted from an early version of the paged list available at http://pagedlist.codeplex.com/.
    /// </remarks>
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1710:IdentifiersShouldHaveCorrectSuffix")]
    public class PagedList<T> : List<T>, IPagedList<T>
    {
        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="PagedList&lt;T&gt;"/> class.
        /// </summary>
        /// <param name="source">The source.</param>
        /// <param name="index">The index.</param>
        /// <param name="pageSize">Size of the page.</param>
        public PagedList(IEnumerable<T> source, int index, int pageSize) : this(source, index, pageSize, null)
    {
    }

        /// <summary>
        /// Initializes a new instance of the <see cref="PagedList&lt;T&gt;"/> class.
        /// </summary>
        /// <param name="source">The source.</param>
        /// <param name="index">The index.</param>
        /// <param name="pageSize">Size of the page.</param>
        /// <param name="totalCount">The total count.</param>
    public PagedList(IEnumerable<T> source, int index, int pageSize, int? totalCount)
    {
      Initialize(source.AsQueryable(), index, pageSize, totalCount);
    }

        /// <summary>
        /// Initializes a new instance of the <see cref="PagedList&lt;T&gt;"/> class.
        /// </summary>
        /// <param name="source">The source.</param>
        /// <param name="index">The index.</param>
        /// <param name="pageSize">Size of the page.</param>
    public PagedList(IQueryable<T> source, int index, int pageSize) : this(source, index, pageSize, null)
    {
    }

        /// <summary>
        /// Initializes a new instance of the <see cref="PagedList&lt;T&gt;"/> class.
        /// </summary>
        /// <param name="source">The source.</param>
        /// <param name="index">The index.</param>
        /// <param name="pageSize">Size of the page.</param>
        /// <param name="totalCount">The total count.</param>
    public PagedList(IQueryable<T> source, int index, int pageSize, int? totalCount)
    {
      Initialize(source, index, pageSize, totalCount);
        }

        #endregion

        #region IPagedList Members

        /// <summary>
        /// Gets the page count.
        /// </summary>
        public int PageCount { get; private set; }
        /// <summary>
        /// Gets the total item count.
        /// </summary>
    public int TotalItemCount { get; private set; }
        /// <summary>
        /// Gets the current page index.
        /// </summary>
    public int PageIndex { get; private set; }
        /// <summary>
        /// Gets the current page number.
        /// </summary>
    public int PageNumber { get { return PageIndex + 1; } }
        /// <summary>
        /// Gets the size of the pages.
        /// </summary>
    public int PageSize { get; private set; }
        /// <summary>
        /// Gets a value indicating whether there is a previous page.
        /// </summary>
    public bool HasPreviousPage { get; private set; }
        /// <summary>
        /// Gets a value indicating whether there is a next page.
        /// </summary>
    public bool HasNextPage { get; private set; }
        /// <summary>
        /// Gets a value indicating whether this is the first page.
        /// </summary>
    public bool IsFirstPage { get; private set; }
        /// <summary>
        /// Gets a value indicating whether this is the last page.
        /// </summary>
    public bool IsLastPage { get; private set; }

    #endregion

        #region Initialize

        /// <summary>
        /// Initializes the paged list.
        /// </summary>
        /// <param name="source">The source.</param>
        /// <param name="index">The index.</param>
        /// <param name="pageSize">Size of the page.</param>
        /// <param name="totalCount">The total count.</param>
    protected void Initialize(IQueryable<T> source, int index, int pageSize, int? totalCount)
    {
      //### argument checking
      if (index < 0)
      {
        throw new ArgumentOutOfRangeException("index", "PageIndex cannot be below 0.");
      }
      if (pageSize < 0)
      {
        throw new ArgumentOutOfRangeException("pageSize", "PageSize cannot be less than 0.");
      }

      //### set source to blank list if source is null to prevent exceptions
      if (source == null)
      {
        source = new List<T>().AsQueryable();
      }

      //### set properties
      if (!totalCount.HasValue)
      {
        TotalItemCount = source.Count();
      }
      PageSize = pageSize;
      PageIndex = index;
      if (TotalItemCount > 0)
      {
        PageCount = (int)Math.Ceiling(TotalItemCount / (double)PageSize);
      }
      else
      {
        PageCount = 0;
      }
      HasPreviousPage = (PageIndex > 0);
      HasNextPage = (PageIndex < (PageCount - 1));
      IsFirstPage = (PageIndex <= 0);
      IsLastPage = (PageIndex >= (PageCount - 1));

      //### add items to internal list
      if (TotalItemCount > 0)
      {
        AddRange(source.Skip((index) * pageSize).Take(pageSize).ToList());
      }
        }

        #endregion
    }
}