c# - 需要 ASP.NET Core 2.0 分页帮助

Question

再次需要帮助。所以我目前正在研究 ASP.NET Core 2.0 Paging，但它无法正常工作。

我按照这里的教程 https://learn.microsoft.com/en-us/aspnet/core/data/ef-mvc/sort-filter-page

但是，问题是教程使用的是 Entity Framework 数据集还是 IQuery？然而，我正在使用 List<>。有谁知道如何解决这个问题或将我的列表转换为 EF 数据集或其他东西？

Controller 分页.cs:

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 - 1) * pageSize).Take(pageSize).ToListAsync();
    return new PaginatedList<T>(items, count, pageIndex, pageSize);
}

Controller :

public async Task<IActionResult> Index(string sortOrder, string currentFilter, string searchString, int? page)
{
    ViewData["CurrentSort"] = sortOrder;
    ViewBag.CurrentSort = sortOrder;
    var students = addList();

    ViewData["NameSortParm"] = String.IsNullOrEmpty(sortOrder) ? "name_desc" : "";
    if (searchString != null)
    {
        page = 1;
    }
    else
    {
        searchString = currentFilter;
    }

    ViewBag.CurrentFilter = searchString;


    switch (sortOrder)
    {
        case "name_desc":
            students = students.OrderByDescending(s => s.Name).ToList();
            break;
        default:
            break;
    }

    if (searchString != null)
    {
        page = 1;
    }
    else
    {
        searchString = currentFilter;
    }

    ViewData["CurrentFilter"] = searchString;
    int pageSize = 3;
    return View(await PaginatedList<Student>.CreateAsync(students.AsNoTracking(), page ?? 1, pageSize));
    // return View(PaginatedList<Student>(students, page ?? 1, pageSize));
}

如果您查看上面的代码，它仅适用于从 EF 检索的数据集。

CountAsync()、students.AsNoTracking() 不起作用，因为它是一个列表。

有人知道我该怎么办吗？如果您需要什么，请告诉我。

谢谢!

编辑:

public IQueryable<Student> addList()
{
    var studentList = new List<Student>();
    studentList.Add(new Student
    {
        Id = 1,
        Name = "David",
        ClassName = "Moria"
    });

    studentList.Add(new Student
    {
        Id = 2,
        Name = "Jenny",
        ClassName = "Moria"
    });

    studentList.Add(new Student
    {
        Id = 3,
        Name = "Crystal",
        ClassName = "Moria"
    });

    studentList.Add(new Student
    {
        Id = 4,
        Name = "jenny",
        ClassName = "Moria"
    });

    studentList.Add(new Student
    {
        Id = 5,
        Name = "Andria",
        ClassName = "Moria"
    });

    studentList.Add(new Student
    {
        Id = 6,
        Name = "Sweet",
        ClassName = "Moria"
    });

    studentList.Add(new Student
    {
        Id = 7,
        Name = "Susan",
        ClassName = "Moria"
    });
    return studentList.AsQueryable();
}

Answer 1

你的 addList()只是在内存中创建一组硬编码数据。使用异步方法(实际上会降低性能)或使用 IQueryable 是没有意义的(您没有查询外部数据源)。

我建议重命名您的 addlist更有意义的方法，比如FetchStudents() .自从您生成 List<Student>在方法中，它应该返回 IList<Student>

public IList<Student> FetchStudents()
{
    ....
    return studentList;
}

接下来更改 CreateAsync()接受方法IEnumerable<T>并删除异步调用

public static PaginatedList<T> Create(IEnumerable<T> source, int pageIndex, int pageSize)
{
    var count = source.Count();
    var items = source.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();
    return new PaginatedList<T>(items, count, pageIndex, pageSize);
}

最后修改Index()方法

public IActionResult Index(string sortOrder, string currentFilter, string searchString, int? page)
{
    ....
    var students = FetchStudents();
    ....
    return View(PaginatedList<Student>.Create(students, page ?? 1, pageSize));
}