EntityFramework进阶（五）- 分页

本系列原创博客代码已在EntityFramework6.0.0测试通过，转载请标明出处

我们创建分页信息类CommonPagedList，包含了字段总条数，总页数，当前页码，页大小，当前页数据。

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

/*

* CopyRight ©2017 All Rights Reserved

* 作者:Rex Sheng

*/

namespace SuperNet.EntityFramework.PagedList

{

    /// <summary>

    /// 共通分页类

    /// </summary>

    /// <typeparam name="T"></typeparam>

    public class CommonPagedList<T> : List<T>

       where T : class

    {

        public int TotalItemCount { get; set; }

        public int PageSize { get; set; }

        public int PageIndex { get; set; }

        public int TotalPageCount { get; set; }

        private CommonPagedList() { }

        public CommonPagedList(CommonPagedList<T> list)

        {

            this.PageIndex = list.PageIndex;

            this.PageSize = list.PageSize;

            this.TotalItemCount = list.TotalItemCount;

            this.TotalPageCount = list.TotalPageCount;

            AddRange(list);

        }

        public CommonPagedList(IQueryable<T> list, int pageIndex, int pageSize)

        {

            if (pageIndex <= )

                pageIndex = ;

            this.TotalItemCount = list.Count();

            this.PageSize = pageSize;

            this.TotalPageCount = this.TotalItemCount % this.PageSize ==  ? this.TotalItemCount / this.PageSize : this.TotalItemCount / this.PageSize + ;

            pageIndex = pageIndex > this.TotalPageCount ? this.TotalPageCount : pageIndex;

            this.PageIndex = pageIndex;

            if (this.PageIndex > this.TotalPageCount)

                this.PageIndex = this.TotalPageCount;

            if (pageIndex <= )

            {

                pageIndex = ;

            }

            if (this.PageIndex <= )

            {

                this.PageIndex = ;

            }

            var query = list.Skip((pageIndex - ) * pageSize).Take(pageSize);

            AddRange(query);

        }

        public CommonPagedList(IEnumerable<T> list, int pageIndex, int pageSize, int totalItemCount)

        {

            if (pageIndex <= )

                pageIndex = ;

            this.TotalItemCount = totalItemCount;

            this.TotalPageCount = totalItemCount % pageSize ==  ? totalItemCount / pageSize : totalItemCount / pageSize + ;

            pageIndex = pageIndex > this.TotalPageCount ? this.TotalPageCount : pageIndex;

            if (pageIndex <= )

                pageIndex = ;

            this.PageIndex = pageIndex;

            this.PageSize = pageSize;

            AddRange(list);

        }

    }

}

调用的时候，我们创建扩展方法来实现

using System;

using System.Collections.Generic;

using System.Linq;

using System.Linq.Expressions;

using System.Text;

using System.Threading.Tasks;

/*

* CopyRight ©2017 All Rights Reserved

* 作者:Rex Sheng

*/

namespace SuperNet.EntityFramework.PagedList

{

    public static class PagedListExtension

    {

        /// <summary>

        /// 共通分页类扩展

        /// </summary>

        /// <typeparam name="T">查询返回类</typeparam>

        /// <param name="allItems">要查询的数据</param>

        /// <param name="pageIndex">要查询的页码</param>

        /// <param name="pageSize">每页大小</param>

        /// <returns></returns>

        public static CommonPagedList<T> ToCommonPagedList<T>(this IOrderedQueryable<T> allItems, int pageIndex, int pageSize) where T : class

        {

            CommonPagedList<T> Result = new CommonPagedList<T>(allItems, pageIndex, pageSize);

            return Result;

        }

        /// <summary>

        /// 单个字段排序分页查询

        /// </summary>

        /// <typeparam name="T">查询返回类</typeparam>

        /// <typeparam name="TKey">排序字段类型</typeparam>

        /// <param name="allItems">要查询的数据</param>

        /// <param name="orderator">排序字段表达式</param>

        /// <param name="asc">是否升序</param>

        /// <param name="pageIndex">要查询的页码</param>

        /// <param name="pageSize">每页大小</param>

        /// <returns></returns>

        public static CommonPagedList<T> ToCommonPagedList<T, TKey>(this IQueryable<T> allItems, Expression<Func<T, TKey>> orderator, bool asc, int pageIndex, int pageSize) where T : class

        {

            var source = asc ? allItems.OrderBy(orderator) : allItems.OrderByDescending(orderator);

            CommonPagedList<T> Result = new CommonPagedList<T>(source, pageIndex, pageSize);

            return Result;

        }

        /// <summary>

        /// 多个字段排序分页查询

        /// </summary>

        /// <typeparam name="T">查询返回类</typeparam>

        /// <typeparam name="TKey1">排序字段类型1</typeparam>

        /// <typeparam name="TKey2">排序字段类型2</typeparam>

        /// <param name="allItems">要查询的数据</param>

        /// <param name="orderator1">排序字段表达式1</param>

        /// <param name="orderator2">排序字段表达式2</param>

        /// <param name="asc1">是否升序1</param>

        /// <param name="asc2">是否升序2</param>

        /// <param name="pageIndex">要查询的页码</param>

        /// <param name="pageSize">每页大小</param>

        /// <returns></returns>

        public static CommonPagedList<T> ToCommonPagedList<T, TKey1, TKey2>(this IQueryable<T> allItems, Expression<Func<T, TKey1>> orderator1, Expression<Func<T, TKey2>> orderator2, bool asc1, bool asc2, int pageIndex, int pageSize) where T : class

        {

            var source = asc1 ? (asc2 ? allItems.OrderBy(orderator1).ThenBy(orderator2) : allItems.OrderBy(orderator1).ThenByDescending(orderator2))

                : (asc2 ? allItems.OrderByDescending(orderator1).ThenBy(orderator2) : allItems.OrderByDescending(orderator1).ThenByDescending(orderator2));

            CommonPagedList<T> Result = new CommonPagedList<T>(source, pageIndex, pageSize);

            return Result;

        }

        /// <summary>

        /// 共通分页类

        /// </summary>

        /// <typeparam name="T">查询返回类</typeparam>

        /// <param name="allItems">要查询的数据</param>

        /// <param name="pageIndex">要查询的页码</param>

        /// <param name="pageSize">每页大小</param>

        /// <returns></returns>

        public static CommonPagedList<T> ToCommonPagedList<T>(this IOrderedEnumerable<T> allItems, int pageIndex, int pageSize) where T : class

        {

            CommonPagedList<T> Result = new CommonPagedList<T>(allItems.AsQueryable(), pageIndex, pageSize);

            return Result;

        }

    }

}

巴特西

EntityFramework进阶（五）- 分页

最新文章

热门文章