分页错误：仅 LINQ to Entities 中的排序输入支持“跳过”方法。方法 'OrderBy' 必须在方法 'Skip' 之前调用

Question

我正在 MVC 中的索引页面上进行分页..在这一行我收到错误

return View( employee.ToPagedList(Page ?? 1,3));

这里是索引方法

 public ActionResult Index(string searchBy, string search, int? Page, string sortBy)
    {
        ViewBag.SortNameParameter = string.IsNullOrEmpty(sortBy) ? "Name desc"
            : "";

        ViewBag.SortGenderParameter = string.IsNullOrEmpty(sortBy) ? "Gender desc"
            : "Gender";

        var employee = db.Employees.AsQueryable();

        if (searchBy == "Gender")
        {
            employee = employee.Where(x => x.Gender == search || search == null);
        }
        else
        {
            employee = employee.Where(x => x.FUllName .StartsWith(search ) || search == null);
        }

        switch (sortBy)
        {
            case "Name desc":
                employee = employee.OrderByDescending(x => x.FUllName);
                break;

            case "Default":
                employee = employee.OrderBy(x => x.FUllName);
                break;
        }

      return View( employee.ToPagedList(Page ?? 1,3));
    }

我没有使用Skip方法...但是有这个错误：

“Skip”方法仅支持 LINQ to 中的排序输入 实体。必须在方法之前调用方法“OrderBy” “跳过”。

我看过类似的帖子

The method 'Skip' is only supported for sorted input in LINQ to Entities. The method 'OrderBy' must be called before the method 'Skip'

How to solve "The method 'Skip' is only supported for sorted input in LINQ to Entities."

The method ‘Skip’ is only supported for sorted input in LINQ to Entities. The method ‘OrderBy’ must be called before the method ‘Skip’

ASP.NET MVC 3 PagedList. The method 'Skip' is only supported for sorted input in LINQ to Entities.

并做了以下更改...

1.将employee.Where代码放在switch语句前：

2. 在你的 switch 语句中添加一个默认情况，并让它抛出。 案例“默认”： throw new ArgumentException("error", sortBy);

1. 使用 IOrderedQueryable 类型。

   IQueryable 员工 = db.Employees.AsQueryable();

这不能解决问题..
大多数情况下，他们使用的是 Skip 方法..但我没有...而且其他帖子查询很复杂..

请提出遗漏的建议

Answer 1

你确实有一个Skip 方法。

PagedList 为您添加了它。检查代码。这就是分页的工作原理，Take 和 Skip。

我也认为你的案例陈述是为了

    switch (sortBy)
    {
        case "Name desc":
            employee = employee.OrderByDescending(x => x.FUllName);
            break;

        default: // Not: case "Default"
            employee = employee.OrderBy(x => x.FUllName);
            break;
    }

Answer 2

请试试这个代码

    var employee = db.Employees.ToList()// Try to change AsQueryable to Ilist or List

    if (searchBy == "Gender")
    {
        employee = employee.Where(x => x.Gender == search || search == null).ToPagedList(Page ?? 1,3);
    }
    else
    {
        employee = employee.Where(x => x.FUllName .StartsWith(search ) || search == null).ToPagedList(Page ?? 1,3);
    }
     switch (sortBy)
    {
        case "Name desc":
            employee = employee.OrderByDescending(x => x.FUllName);
            break;

        case "Default":
            employee = employee.OrderBy(x => x.FUllName);
            break;
    }

      return View( employee);