.net core模糊查询及分页

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;namespace FineUICore.Examples
{
public class PaginatedList<T> : List<T>
{
public int PageIndex { get; private set; }//当前页
public int TotalPages { get; private set; }//总页数 public PaginatedList(List<T> items, int count, int pageIndex, int pageSize)//count：总条数 ，pageIndex：当前页，pageSize：每页显示行数
{
PageIndex = pageIndex;
TotalPages = (int)Math.Ceiling(count / (double)pageSize); this.AddRange(items);
}
//判断是否为首页
public bool HasPreviousPage
{
get
{
return (PageIndex > );
}
}
//判断是否为尾页
public bool HasNextPage
{
get
{
return (PageIndex < TotalPages);
}
} public static async Task<PaginatedList<T>> CreateAsync(IQueryable<T> source, int pageIndex, int pageSize)
{
var count = await source.CountAsync();
var items = await source.Skip((pageIndex - ) * pageSize).Take(pageSize).ToListAsync();
return new PaginatedList<T>(items, count, pageIndex, pageSize);
}
}
}

public async Task<IActionResult> Index(
string sortOrder,
string currentFilter,
string searchString,
int? page)
{
ViewData["CurrentSort"] = sortOrder;
ViewData["NameSortParm"] = String.IsNullOrEmpty(sortOrder) ? "name_desc" : "";
ViewData["DateSortParm"] = sortOrder == "Date" ? "date_desc" : "Date"; if (searchString != null)
{
page = ;
}
else
{
searchString = currentFilter;
} ViewData["CurrentFilter"] = searchString; var students = from s in _context.Students
select s;
if (!String.IsNullOrEmpty(searchString))
{
students = students.Where(s => s.LastName.Contains(searchString)
|| s.FirstMidName.Contains(searchString));
}
switch (sortOrder)
{
case "name_desc":
students = students.OrderByDescending(s => s.LastName);
break;
case "Date":
students = students.OrderBy(s => s.EnrollmentDate);
break;
case "date_desc":
students = students.OrderByDescending(s => s.EnrollmentDate);
break;
default:
students = students.OrderBy(s => s.LastName);
break;
} int pageSize = ;
return View(await PaginatedList<Student>.CreateAsync(students.AsNoTracking(), page ?? , pageSize));
}

@model PaginatedList<ContosoUniversity.Models.Student>@{
ViewData["Title"] = "Index";
}<h2>Index</h2>
<p>
<a asp-action="Create">Create New</a>
</p><form asp-action="Index" method="get">
<div class="form-actions no-color">
<p>
Find by name: <input type="text" name="SearchString" value="@ViewData["currentFilter"]" />
<input type="submit" value="Search" class="btn btn-default" /> |
<a asp-action="Index">Back to Full List</a>
</p>
</div>
</form><table class="table">
<thead>
<tr>
<th>
<a asp-action="Index" asp-route-sortOrder="@ViewData["NameSortParm"]" asp-route-currentFilter="@ViewData["CurrentFilter"]">Last Name</a>
</th>
<th>
First Name
</th>
<th>
<a asp-action="Index" asp-route-sortOrder="@ViewData["DateSortParm"]" asp-route-currentFilter="@ViewData["CurrentFilter"]">Enrollment Date</a>
</th>
<th></th>
</tr>
</thead>
<tbody>
@foreach (var item in Model)
{
<tr>
<td>
@Html.DisplayFor(modelItem => item.LastName)
</td>
<td>
@Html.DisplayFor(modelItem => item.FirstMidName)
</td>
<td>
@Html.DisplayFor(modelItem => item.EnrollmentDate)
</td>
<td>
<a asp-action="Edit" asp-route-id="@item.ID">Edit</a> |
<a asp-action="Details" asp-route-id="@item.ID">Details</a> |
<a asp-action="Delete" asp-route-id="@item.ID">Delete</a>
</td>
</tr>
}
</tbody>
</table>@{
var prevDisabled = !Model.HasPreviousPage ? "disabled" : "";
var nextDisabled = !Model.HasNextPage ? "disabled" : "";
}<a asp-action="Index"
asp-route-sortOrder="@ViewData["CurrentSort"]"
asp-route-page="@(Model.PageIndex - 1)"
asp-route-currentFilter="@ViewData["CurrentFilter"]"
class="btn btn-default @prevDisabled">
Previous
</a>
<a asp-action="Index"
asp-route-sortOrder="@ViewData["CurrentSort"]"
asp-route-page="@(Model.PageIndex + 1)"
asp-route-currentFilter="@ViewData["CurrentFilter"]"
class="btn btn-default @nextDisabled">
Next
</a>