c# - Mvc Asp 排序项目

Question

我在我的应用程序中使用 PagedList.MVC 进行分页。这工作正常。分页工作正常，OrderBy 下拉列表也工作正常。当我从下拉列表中选择值时，它会给出所需的排序结果。我的意思是，如果我选择 A-Z，那么它会按升序对项目进行排序，但是当我单击第二页或下一页时，它不会对任何项目进行排序，并且 url 会变成这样

http://localhost:41213/Home/Products?page=2&pageSize=6

还有我怎样才能使这个 pageSize=6 成为动态的？我希望将其放入 {5,10,15,20} 之类的下拉列表中，当用户选择一个值时，它应该显示所选的项目数。

Controller

    [HttpGet]
    public ActionResult Products(int? OrderBy, int page=1, int pageSize=6)
    {
        private Shopping db = new Shopping();
        switch (OrderBy)
        {
            case 1:
                List<Product> listProductsasc = db.Products.OrderBy(p => p.Name).ToList();
                PagedList<Product> modelasc = new PagedList<Product>(listProductsasc, page, pageSize);
                return View(modelasc);
            case 2:
                List<Product> listProductsdesc = db.Products.OrderByDescending(p => p.Name).ToList();
                PagedList<Product> modeldesc = new PagedList<Product>(listProductsdesc, page, pageSize);
                return View(modeldesc);
            default:
                List<Product> listProducts = db.Products.ToList();
                PagedList<Product> modeldefault = new PagedList<Product>(listProducts, page, pageSize);
                return View(modeldefault);
        }
    }

查看

@model PagedList.IPagedList<FypStore.Models.Product>
@using PagedList.Mvc
<div class="row">
        <div class="col-sm-6">
            @using (Html.BeginForm("Products", "Home", FormMethod.Get, new { id = "Form1" }))
            {
                <div class="col-sm-8">
                    Sort by:
                    @Html.DropDownList("OrderBy", new List<SelectListItem>

                     {
                        new SelectListItem{ Text="A-Z", Value = "1" },
                        new SelectListItem{ Text="Z-A", Value = "2" }
                     }, "-- Order By --")

                </div>
                <div class="col-sm-4">
                    <div class="form-group">
                        <div class="col-md-offset-2 col-md-10">
                            <input type="submit" class="btn btn-default" value="Filter" />
                        </div>
                    </div>
                </div>
            }
        </div>
</div>
<br />

@Html.PagedListPager(Model, page => Url.Action("Products", new { page, pageSize = Model.PageSize }))
Showing @Model.FirstItemOnPage to @Model.LastItemOnPage of @Model.TotalItemCount Products

Answer 1

需要修改PagedListPager()方法的路由参数，使其包含排序顺序的值，例如

@Html.PagedListPager(Model, page => Url.Action("Products", new { OrderBy = ViewBag.SortOrder, page, pageSize = Model.PageSize }))

然后在方法中，包含

ViewBag.SortOrder = OrderBy;

在返回 View 之前。然而，更好的方法是使用包含 View 使用的属性的 View 模型，这将解决代码的其他问题(例如，如果您选择 "Z-A" 选项并提交表单，当您返回它，集合已排序，但下拉列表显示 "-- Order By --" 表示其未排序。您的 View 模型应该是

public class ProductsVM
{
  [Display(Name = "Sort by:")]
  public int? OrderBy { get; set; }
  public IEnumerable<SelectListItem> OrderList { get; set; }
  public int Page { get; set; }
  public int PageSize { get; set; }
  PagedList<Product> Products { get; set; }
}

Controller 方法是

[HttpGet]
public ActionResult Products(int? orderBy, int page=1, int pageSize=6)
{
  private Shopping db = new Shopping();
  IEnumerable<Product> products = db.Products; // not .ToList()
  if (orderBy == 1)
  {
    products = products.OrderBy(p => p.Name);
  }
  else if (orderBy == 2)
  {
    products = products.OrderByDescending(p => p.Name)
  }

  ProductsVM model = new ProductsVM
  {
    OrderBy = orderBy,
    OrderList = new List<SelectListItem>
    {
      new SelectListItem{ Text="A-Z", Value = "1" },
      new SelectListItem{ Text="Z-A", Value = "2" }
    },
    Page = page,
    PageSize = pageSize,
    Products = new PagedList<Product>(products, page, pageSize);
  };
  return View(model);
}

最后修改 View 以使用 View 模型

@model ProductsVM
....
@using (Html.BeginForm("Products", "Home", FormMethod.Get))
{
  @Html.LabelFor(m => m.OrderBy)
  @Html.DropDownListForFor(m => m.OrderBy, Model.OrderList, "-- Order By --")
  <input type="submit" class="btn btn-default" value="Filter" />
}

@Html.PagedListPager(Model.Products, page => Url.Action("Products", new { orderBy = Model.OrderBy, page, pageSize = Model.PageSize }))
Showing @Model.Products.FirstItemOnPage to @Model.Products.LastItemOnPage of @Model.Products.TotalItemCount Products