nop前端分页实现思路及步骤

注：nop本身已经有啦可以实现分页的类，所以我们直接去使用就可以啦 。

（编程部分）步骤如下：

第一步，针对Model操作，在需要使用分页的界面Model中将分页类作为该Model类的成员，并在Modle的构造函数中实例化。代码如下：

public class NeedMessagePagerModel : BaseNopModel
    {
        public NeedMessagePagerModel()
        {
            PagingFilteringContext = new NewsPagingFilteringModel();
      
        }

        public NewsPagingFilteringModel PagingFilteringContext { get; set; }
      
    }
//NeedMessagePagerModel 为界面Model

第二步，针对控制器操作，方法需要参数，代码如下：

public ActionResult NewSchoolMessage(NewsPagingFilteringModel command)
        {
            DxcMessagePagerModel modelList = new DxcMessagePagerModel();
            if (command.PageSize <= 0) command.PageSize = 10;
            if (command.PageNumber <= 0) command.PageNumber = 1;
          //entitys为从数据库中查询出的数据，并判断是否为空，不为空是进行分页操作
                 if(entitys==null){
                       return view();
                     }  
          
            var page = new PagedList<实体Model>(entitys, command.PageNumber - 1, command.PageSize);
            modelList.PagingFilteringContext.LoadPagedList(page);

            modelList.BaseMessagesItems = page.Select(x =>//BaseMessagesItems为在BaseMessageModel中自定义的并实例化的容器装所需数据的容器
            {
                BaseMessageModel model = new BaseMessageModel();
                model.Id = x.Id;
                model.Title = x.Title;
                model.PictureUrl = x.Picture == null ? "" : _pictureService.GetPictureUrl((int)x.Picture);
            
                return model;
            }).ToList();

            return View(modelList);
        }
//BaseMessageModel为另一个视图Model

第三步，针对视图端的操作，代码如下：

@{
                var pager = Html.Pager(Model.PagingFilteringContext).QueryParam("pagenumber");
            }
            @if (!pager.IsEmpty())
            {
                <div class="pager">
                    @pager
                </div>
            }

以下为：实现原理的版本（单独系统开发时可以根据步骤加入使用）

第一步，接口定义，代码如下：

public interface IPageableModel
    {
        /// <summary>
        /// The current page index (starts from 0)
        /// </summary>
        int PageIndex { get; }
        /// <summary>
        /// The current page number (starts from 1)
        /// </summary>
        int PageNumber { get; }
        /// <summary>
        /// The number of items in each page.
        /// </summary>
        int PageSize { get; }
        /// <summary>
        /// The total number of items.
        /// </summary>
        int TotalItems { get; }
        /// <summary>
        /// The total number of pages.
        /// </summary>
        int TotalPages { get; }
        /// <summary>
        /// The index of the first item in the page.
        /// </summary>
        int FirstItem { get; }
        /// <summary>
        /// The index of the last item in the page.
        /// </summary>
        int LastItem { get; }
        /// <summary>
        /// Whether there are pages before the current page.
        /// </summary>
        bool HasPreviousPage { get; }
        /// <summary>
        /// Whether there are pages after the current page.
        /// </summary>
        bool HasNextPage { get; }
    }

第二步，实现继承，代码如下：

public abstract class BasePageableModel : IPageableModel
    {
        #region Methods

        public virtual void LoadPagedList<T>(IPagedList<T> pagedList)
        {
            FirstItem = (pagedList.PageIndex * pagedList.PageSize) + 1;
            HasNextPage = pagedList.HasNextPage;
            HasPreviousPage = pagedList.HasPreviousPage;
            LastItem = Math.Min(pagedList.TotalCount, ((pagedList.PageIndex * pagedList.PageSize) + pagedList.PageSize));
            PageNumber = pagedList.PageIndex + 1;
            PageSize = pagedList.PageSize;
            TotalItems = pagedList.TotalCount;
            TotalPages = pagedList.TotalPages;
        }

        #endregion

        #region Properties

        public int FirstItem { get; set; }

        public bool HasNextPage { get; set; }

        public bool HasPreviousPage { get; set; }

        public int LastItem { get; set; }

        public int PageIndex
        {
            get
            {
                if (PageNumber > 0)
                    return PageNumber - 1;
                
                return 0;
            }
        }

        public int PageNumber { get; set; }

        public int PageSize { get; set; }

        public int TotalItems { get; set; }

        public int TotalPages { get; set; }

        #endregion
    }

第三步，继承抽象方法可以不实现从而直接使用父类的方法，（抽象方法不能实例化）。代码如下：

public partial class NewsPagingFilteringModel : BasePageableModel
    {
    }

最后步骤：通上述编程部分的步骤一，二，三。