Question

尝试在Controller中实现PagedList时，我一直收到此错误。确切的错误读取

＆＃39; DataIntelligence.Models.Execution＆＃39;不包含＆＃39; ToPagedList＆＃39;的定义没有扩展方法＆＃39; ToPagedList＆＃39;接受类型＆＃39; DataIntelligence.Models.Execution＆＃39;的第一个参数。可以找到（你错过了使用指令或汇编引用吗？）`

我不明白为什么。我看过类似的问题，但似乎无法找到我想要的答案。我想知道是否有人可以提供帮助。

控制器

using DataIntelligence.Models;
using PagedList;
using PagedList.Mvc;
using System;
using System.Linq;
using System.Web.Mvc;

public ActionResult Execution(int? page, int id = 0)
{
    var execution = db.Executions.Find(id);

    if (execution == null)
    {
        return HttpNotFound();
    }

    ViewBag.ExecutionSeconds = (execution.End - execution.Start).ToString(@"dd\.hh\:mm\:ss\.fff");

    int pageSize = Int32.Parse(System.Configuration.ConfigurationManager.AppSettings["DefaultPageSize"]);
                int pageNumber = (page ?? 1);
    return View(execution.ToPagedList(pageNumber, pageSize));
}

执行模型

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Web;


namespace DataIntelligence.Models
{
    [Table("Execution")]
    public class Execution
    {
        public int Id { get; set; }
        public Int16 PackageId { get; set; }
        public DateTime Start { get; set; }
        public DateTime End { get; set; }
        public Boolean Successful { get; set; }

        public virtual ICollection<Step> Steps { get; set; }
    }
}

视图

@model PagedList.IPagedList<DataIntelligence.Models.Execution>
@using PagedList.Mvc;

<link href="Content/PagedList.css" rel="stylesheet" type="text/css" />

@{
    ViewBag.Title = "Execution Details";
}
<script language="javascript" type="text/javascript" src="jquery-1.8.3.js">    </script>
<script>
    function goBack() {
        window.history.back();
    }
</script>
<div class="jumbotron">
    <h2>Execution Details</h2>
</div>

<fieldset>
    <legend>Execution Id - @Html.DisplayFor(model => model.Id)</legend>

    <div class="row">
        <div class="col-sm-3">
            <div class="display-label">
                @Html.DisplayNameFor(model => model.PackageId)
            </div>
            <div class="display-field">
                <a href="@Url.Action("Package", new { id=Model.PackageId})"> @Html.DisplayFor(model => model.PackageId) </a>
            </div>
        </div>

        <div class="col-sm-3">
            <div class="display-label">
                @Html.DisplayNameFor(model => model.Start)
            </div>
            <div class="display-field">
                @Html.DisplayFor(model => model.Start)
            </div>
        </div>
        <div class="col-sm-3">
            <div class="display-label">
                @Html.DisplayNameFor(model => model.End)
            </div>
            <div class="display-field">
                @Html.DisplayFor(model => model.End)
            </div>
        </div>
        <div class="col-sm-3">
            <div class="display-label">
                Execution Time
            </div>
            <div class="display-field">
                @ViewBag.ExecutionSeconds
            </div>
        </div>
    </div>
    <div class="row">
        <div class="col-sm-3">
            <div class="display-label">
                @Html.DisplayNameFor(model => model.Successful)
            </div>
            <div class="display-field">
                @Html.DisplayFor(model => model.Successful)
            </div>
        </div>
    </div>
    <br />
</fieldset>

<table>
    <tr>
        <th>
            Step ID
        </th>
        <th id="stepname">
            Name
        </th>
        <th id="stepdate">
            Date
        </th>
    </tr>

    @foreach (var step in Model.Steps) {
       <tr>
            <td>
               @Html.DisplayFor(modelItem => step.Id)
            </td>
            <td id="steps">
                @Html.DisplayFor(modelItem => step.Name)
            </td>
            <td id="date">
                @Html.DisplayFor(modelItem => step.Date)
            </td>
        </tr>
    }
</table>
<button class="btn btn-link" onclick="goBack()" style="padding-right: 0px; padding-top: 0px; padding-bottom: 0px; padding-left: 0px;">Back</button>

Page @(Model.Steps.PageCount < Model.Steps.PageNumber ? 0 :  Model.Steps.PageNumber) of @Model.Steps.PageCount
@Html.PagedListPager(Model.Steps, page => Url.Action("Execution", new { page, sortOrder = ViewBag.CurrentSort}))

Answer 1

DbSet.Find方法返回实体的单个实例，而不是枚举。因此将ToPagedList应用于此是没有意义的。如果您确实想将其包装在分页列表中，可以将查询更改为：

var executions = db.Executions.Where(e => e.Id == id);

这将为您提供只有一个值的IEnumerable结果。

修改

阅读完评论后，您似乎确实只想对Steps属性进行分页。要做到这一点，最好创建一个视图模型而不是将数据库实体直接传递给视图，注意我如何将Steps属性的类型更改为分页列表：

public class ExecutionViewModel
{
    public int Id { get; set; }
    public Int16 PackageId { get; set; }
    public DateTime Start { get; set; }
    public DateTime End { get; set; }
    public Boolean Successful { get; set; }

    public virtual PagedList.IPagedList<Step> Steps { get; set; }
}

没有你的控制器变成这样：

public ActionResult Execution(int? page, int id = 0)
{
    var execution = db.Executions.Find(id);

    if (execution == null)
    {
        return HttpNotFound();
    }

    ViewBag.ExecutionSeconds = (execution.End - execution.Start).ToString(@"dd\.hh\:mm\:ss\.fff");

    int pageSize = Int32.Parse(System.Configuration.ConfigurationManager.AppSettings["DefaultPageSize"]);
    int pageNumber = (page ?? 1);

    var executionModel = new ExecutionViewModel
    {
        Id = execution.Id,
        PackageId = execution.PackageId,
        Start = execution.Start,
        End = execution.End,
        Successful = execution.Successful,
        Steps = execution.Steps.ToPagedList(pageNumber, pageSize)
    };
    return View(executionModel);
}

不要忘记更改视图以获取新对象：

@model DataIntelligence.ViewModels.ExecutionViewModel

Answer 2

通过NuGet添加以下内容：

PM> Install-Package PagedList.MVC

在您的控制器中，添加以下内容：

using PagedList;

在您看来，添加以下内容：

@using PagedList.Mvc;

不包含ToPagedList的定义

控制器

执行模型

视图

2 个答案:

修改