Question

刚刚使用Paged List插件将分页添加到我的视图中，我只能将数据带回一页。如果您单击“下一步”或任何其他可用页码，页面将重新提交，您最后会看到一个空白表格。

我逐步完成代码，发现传递回控制器的视图模型对象完全为null。有没有人知道这种方法（即导航到不同的分页列表页面时保留视图模型数据）？

查看模型

public class ZipCodeIndex
{
    [DisplayName("Zip Code")]
    public string searchZip { get; set; }
    public IEnumerable<SelectListItem> StateCodes { get; set; }
    [DisplayName("Effective on this date")]
    public string searchDate { get; set; }
    [DisplayName("State")]
    public string searchState { get; set; }
    [DisplayName("Territory")]
    public string searchTerritory { get; set; }
    [DisplayName("New Territory")]
    public string newTerritory { get; set; }
    [DisplayName("New Description")]
    public string newDescription { get; set; }
    [DisplayName("New Effective Date")]
    public string newEffectiveDate { get; set; }

    public IPagedList<ZipCodeTerritory> pagedTerritoryList { get; set; }
    public List<ZipCodeTerritory> zipCodeTerritory { get; set; }

    public ZipCodeIndex() 
    {
        zipCodeTerritory = new List<ZipCodeTerritory>();
        SetStateCodes();
    }

    //Set state code drop down list
    private void SetStateCodes()
    {
        AgentResources db = new AgentResources();
        StateCodes = (from z in db.ZipCodeTerritory
                      select z.StateCode).Select(x => new SelectListItem
                      {
                          Text = x,
                          Value = x
                      }).Distinct().ToList();

        db.Dispose();
    }
}

控制器

    public ViewResult Index(int? page, string errorMessage = "", ZipCodeIndex search = null)
    {
        //set Paged List counter variables
        int pageNumber = page ?? 1;
        int pageSize = 300;

        //If TempData conntains information method call came from another controller action
        if (TempData.Count > 0)
        {
            //Instantiate ZipCodeIndex view model object if it exists
            search = (ZipCodeIndex)TempData["ZipCodeIndexData"];

            //Clear out previous search results
            search.zipCodeTerritory.Clear();
        }

        //Proceed with search
        try
        {
            //If search criteria is null page is loading for the first time so send blank view 
            if (String.IsNullOrWhiteSpace(search.searchZip) &&
                String.IsNullOrWhiteSpace(search.searchDate) &&
                String.IsNullOrWhiteSpace(search.searchState))
            {
                if (!string.IsNullOrWhiteSpace(search.searchTerritory))
                {
                    ViewBag.ErrorMessage = "State or Zip Code required for search.";
                }

                //Convert list to IPagedList for pagining on Index
                search.pagedTerritoryList = search.zipCodeTerritory.ToPagedList(pageNumber, pageSize);

                return View(search);
            }

            //Determine if necessary search criteria has been sent
            if (String.IsNullOrWhiteSpace(search.searchZip) && String.IsNullOrWhiteSpace(search.searchState))
            {
                ViewBag.ErrorMessage = "Either State or Zip Code Must be Specified";

                //Convert list to IPagedList for pagining on Index
                search.pagedTerritoryList = search.zipCodeTerritory.ToPagedList(pageNumber, pageSize);

                return View(search);
            }

            DateTime effectiveDate;

            //Convert date string to DateTime type
            if (String.IsNullOrWhiteSpace(search.searchDate))
            {
                effectiveDate = DateTime.MinValue;
            }
            else
            {
                effectiveDate = Convert.ToDateTime(search.searchDate);
            }

            //Conduct search by State Code/Date alone
            if (String.IsNullOrWhiteSpace(search.searchZip))
            {
                if (string.IsNullOrWhiteSpace(search.searchTerritory))
                {
                    search.zipCodeTerritory = (from z in db.ZipCodeTerritory
                                               where z.StateCode.Equals(search.searchState) &&
                                                     z.EffectiveDate >= effectiveDate
                                               select z).ToList();
                }
                else
                {
                    search.zipCodeTerritory = (from z in db.ZipCodeTerritory
                                               where z.StateCode.Equals(search.searchState) &&
                                                     z.IndDistrnId.Equals(search.searchTerritory) &&
                                                     z.EffectiveDate >= effectiveDate
                                               select z).ToList();
                }

                //Convert list to IPagedList for pagining on Index
                search.pagedTerritoryList = search.zipCodeTerritory.ToPagedList(pageNumber, pageSize);

            }

            return View(search);
    }

查看

@model Monet.ViewModel.ZipCodeIndex

@{
    ViewBag.Title = "Zip Code Territory Search";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

@using PagedList.Mvc;
@using PagedList;

<h2>Zip Code Territory</h2>

    @using (Html.BeginForm("Index", "ZipCodeTerritory", FormMethod.Post))
    {
        <div class="error" id="searchErrors">
            @ViewBag.ErrorMessage            
        </div>    
        <br/>
        <div id="searchBox" class="boxMe">
            <div id="zipBox">
                @Html.Raw("Zip Code")
                @Html.TextAreaFor(model => model.searchZip, new { style = "width: 300px;", placeholder = "Enter up to 35 comma separated zip codes" }) 
            </div>
            <div id="dateBox">
                @Html.LabelFor(model => model.searchDate)
                @Html.TextBoxFor(model => model.searchDate, new { style="width: 80px;"})
                <div id="terrBox">
                     @Html.LabelFor(model => model.searchTerritory)
                     @Html.TextBoxFor(model => model.searchTerritory, new { style = "width: 30px;padding-left:10px;", maxLength = 3 })                   
                </div>
            </div>
            <div id="stateBox">
                @Html.LabelFor(model => model.searchState)
                @Html.DropDownListFor(model => model.searchState, Model.StateCodes, "  ")
                <button type="submit" id="SearchButton">Search</button>
            </div>
        </div>
        <div style="clear: both;"></div>
    }

<br/>
@Html.ActionLink("Create New", "Create")
<br/>
<br/>
<div class="error" id="updateErrors">
    @ViewBag.UpdateAction            
</div>
@if (Model.zipCodeTerritory.Count > 0)
{
    using (Html.BeginForm("Update", "ZipCodeTerritory", FormMethod.Post))
    {
        @Html.HiddenFor(model => model.searchZip)
        @Html.HiddenFor(model => model.searchDate)
        @Html.HiddenFor(model => model.searchState)

        <div id="cloneBox">
            @Html.LabelFor(model => model.newTerritory)
            @Html.TextBoxFor(model => model.newTerritory, new { style = "width: 30px;padding-left:10px;", maxLength = 3 })
            @Html.LabelFor(model => model.newDescription)
            @Html.TextBoxFor(model => model.newDescription, new { style = "width: 250px;padding-left:10px;", maxLength = 30 })  
            @Html.LabelFor(model => model.newEffectiveDate)     
            @Html.TextBoxFor(model => model.newEffectiveDate, new { style = "width: 80px;padding-left:10px;" })   
        </div>
        <br/>
        <div id="buttonDiv">
            <button type="submit" id="CloneButton" name="button" value="clone">Update Selected Items</button>
            <button type="submit" id="deleteButton" name="button" value="delete">Delete Selected Items</button>            
        </div>
        <div id="pagingDiv">
            @Html.PagedListPager(Model.pagedTerritoryList, page => Url.Action("Index", new { page })) 
        </div>
        <table id="thetable" class="tablesorter" >
            <thead>
                <th>@Html.CheckBox("SelectAll")</th>
                <th>Channel</th>
                <th>Territory</th>
                <th>Description</th>
                <th>State</th>
                <th>Zip</th>
                <th>Effective</th>
                <th>End Date</th>
                <th>Last Update By</th>
                <th>Last Update Date</th>
                <th></th>
            </thead>
            <tbody id="tableBody">
                @for (int i = 0; i < Model.pagedTerritoryList.Count; i++)
                {
                    <tr>
                        <td>
                            @Html.CheckBoxFor(model => model.pagedTerritoryList[i].Update)
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].Update)
                        </td>
                        <td>
                            @Html.DisplayFor(model => model.pagedTerritoryList[i].ChannelCode)
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].ChannelCode)
                        </td>
                        <td>
                            @Html.DisplayFor(model => model.pagedTerritoryList[i].IndDistrnId)
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].IndDistrnId)
                        </td>
                        <td>
                            @Html.DisplayFor(model => model.pagedTerritoryList[i].DrmTerrDesc)
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].DrmTerrDesc)
                        </td>
                        <td>
                            @Html.DisplayFor(model => model.pagedTerritoryList[i].StateCode)
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].StateCode)
                        </td>
                        <td>
                            @Html.DisplayFor(model => model.pagedTerritoryList[i].ZipCode)
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].ZipCode)
                        </td>
                        <td>
                            @Html.DisplayFor(model => model.pagedTerritoryList[i].EffectiveDate)
                            @Html.HiddenFor(model => model.zipCodeTerritory[i].EffectiveDate)
                        </td>
                        <td>
                            @Html.DisplayFor(model => model.pagedTerritoryList[i].EndDate)
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].EndDate)
                        </td>
                        <td>
                            @Html.DisplayFor(model => model.pagedTerritoryList[i].LastUpdateId)
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].LastUpdateId)
                        </td>
                        <td>
                            @Html.DisplayFor(model => model.pagedTerritoryList[i].LastUpdateDate)
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].LastUpdateDate)
                        </td>
                        <td>
                            @Html.ActionLink("Edit", "Edit", new { id = Model.pagedTerritoryList[i].Id })
                            @Html.HiddenFor(model => model.pagedTerritoryList[i].Id)
                        </td>
                    </tr>
                }
            </tbody>
        </table>
    }
}

修改

发现this article并相应地更改了我的@Html.PagedListPager，但没有运气（仍然传递null视图模型对象，现在甚至传递null page参数...）< / p>

    <div id="pagingDiv">
        @Html.PagedListPager(Model.pagedTerritoryList, page => Url.Action("Index", new RouteValueDictionary()
            {
                { "Page", Page},
                { "search", Model }
            }), PagedListRenderOptions.PageNumbersOnly)
    </div>

Answer 1

我知道自从这个问题出现以来已经有一年左右了，但我最近找到了一个简单的解决方案来解决这个问题并想分享。最后一个答案是部分正确的，但有一个更简单的方法来实现这一点。

以下是将viewmodel数据从视图传递到控制器并保留数据的示例代码。

让我们说这是你的viewmodel：

public class SearchViewModel
{
    public int? Page { get; set; }
    public string data1 { get; set; }
    public string data2 { get; set; }
    public string data3 { get; set; }
    public string data4 { get; set; }
    public IPagedList SearchResults { get; set; }
    public string SearchButton { get; set; }
}

你的简单viewmodel构造方法（没有实际的搜索代码，用作例子）：

public ActionResult Index(SearchViewModel model) {

    //code using and constructing your returned search results

    var pageNumIndex = model.Page ?? 1;
    model.SearchR = results.ToPagedList(pageIndex, 25);
    return View(model);
}

然后在您看来，@ Html.PagedListPager看起来像：

@Html.PagedListPager(Model.SearchR, Page => Url.Action("Index", new RouteValueDictionary() {
    { "Page", Page },
    { "data1", Model.data1 },
    { "data2", Model.data2 },
    { "data3", Model.data3 },
    { "data4", Model.data4 },
}),
PagedListRenderOptions.PageNumbersOnly)

这种方法将RouteValueDictionary（）直接实现到Html.PagedListPager中。

我很难找到使用viewmodel方法的@ Html.PagedListPager解决方案，直到发现RouteValueDictionary（）直接方法。

Answer 2

您修改后的代码只会将参数发送到索引页面：Page，并进行搜索。页面是您想要的页面值，但搜索可能是您的模型类的ToString。

我自己一直在努力解决这个问题，并提出了以下解决方案：我已将此方法添加到我的模型中，

public RouteValueDictionary GenerateRouteValueDictionary(int page)
    {
        Page = page;
        RouteValueDictionary dic = new RouteValueDictionary
        {
            { QueryHelper.Print(() => Page), Page },
            { QueryHelper.Print(() => PreviousSortField), PreviousSortField },
            { QueryHelper.Print(() => SortOrder), SortOrder },
            { QueryHelper.Print(() => SearchString), SearchString }, 
            { QueryHelper.Print(() => IncludeHidden), IncludeHidden },
            { QueryHelper.Print(() => SearchOperator1), SearchOperator1 },
            { QueryHelper.Print(() => SearchField1), SearchField1 },
            { QueryHelper.Print(() => SearchField1Value), SearchField1Value },
            { QueryHelper.Print(() => WhereOperator), WhereOperator },
            { QueryHelper.Print(() => SearchOperator2), SearchOperator2 },
            { QueryHelper.Print(() => SearchField2), SearchField2 },
            { QueryHelper.Print(() => SearchField2Value), SearchField2Value },
            { QueryHelper.Print(() => FilterByDummyLocations), FilterByDummyLocations },
            { QueryHelper.Print(() => FilterByDummyProfile), FilterByDummyProfile },
            { QueryHelper.Print(() => FilterNoDevice), FilterNoDevice }
        };
        return dic;
    }

从我的cshtml中，我按如下方式生成分页列表：

@Html.PagedListPager(Model.SearchResults, page => Model.GenerateRouteValueDictionary(page)));

（QueryHelper.Print只是一个打印我提供的属性名称的方法...所以我有效地为每个链接重新创建查询字符串。可能不是处理这个问题的最好方法，但它确实有效。

还有另一种方法，首先在模型上设置页码，然后提供模型本身：

@Html.PagedListPager(Model.SearchResults, page => Url.Action(action, Model.SetPage(page)))

使用这种额外的模型方法：

    public SearchPbxUsersModel SetPage(int page)
    {
        Page = page;
        SearchPbxUsersModel myModel = this.MemberwiseClone() as SearchPbxUsersModel;
        myModel.SearchResults = null;
        return myModel;
    }

除了克隆之外，您还可以将任何您不喜欢的值置空（并且您甚至必须使某些值无效，例如IPagedList pagedTerritoryList）。

任何一种方法都有一个警告：

如果你还有一个多选控件，你将被卡住，并且必须手动编写你自己的动作链接（真是太痛苦了）。使用第一种方法不会起作用，因为使用multiselect可以多次使用多选控件的查询字符串属性（并且不会使用任何字典），而使用第二种方法，您的容器将保持选中状态值（例如List或IEnumerable）将获得ToString（），因此您的模型将保留一个值，而不是查看您选择的值，而是容器的串串。

使用分页列表时丢失所有视图模型数据

2 个答案: