学习ASP.NET Core Razor 编程系列十七——分组

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks; 

namespace RazorMvcBooks.Models.ViewModels
{

    public class EnrollmentPublishGroup
    {
        public string Publish { get; set; }
        public int BooksCount { get; set; } 

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using Microsoft.AspNetCore.Mvc.RazorPages;
using RazorMvcBooks.Models.ViewModels; 

namespace RazorMvcBooks.Pages
{

    public class AboutModel : PageModel
    {

        public string Message { get; set; }

        public async Task OnGetAsync()
        {
            Message = "Your application description page."; 

            IQueryable<EnrollmentPublishGroup> data =
                from book in _context.Book
                group book by book.Publishing into publishGroup

                select new EnrollmentPublishGroup()
                {

                    Publish = publishGroup.Key,
                    BooksCount = publishGroup.Count()

                }; 

            BookGroup =  await data.AsNoTracking().ToListAsync();

        }
        private readonly RazorMvcBooks.Models.BookContext _context;

        public AboutModel(RazorMvcBooks.Models.BookContext context)

        {
            _context = context;
        } 

        public IList<EnrollmentPublishGroup> BookGroup { get; set; }
    }

}

 

@page
@model AboutModel
@{
    ViewData["Title"] = "书籍统计信息";
}

<h2>@ViewData["Title"]</h2>
<h3>@Model.Message</h3> 

<p>Use this area to provide additional information.</p> 

<h2>书籍统计信息</h2>

<table>
    <tr>
        <th>
            出版社

        </th>
        <th>
            书籍数量

        </th>
    </tr> 

    @foreach (var item in Model.BookGroup)
    {

        <tr>
            <td>
                @Html.DisplayFor(modelItem => item.Publish)

            </td>
             <td align="right">

                @item.BooksCount
            </td>

        </tr>
    }
</table>