Question

我是MVC的新手。我希望得到＆＃34; fromDate＆＃34;和＃34; ToDate＆＃34;从一个角度来看。在同一视图中，我需要三个空的隐藏的DropDownLists。

点击提交按钮后，这些DropDownLists应该是可见的，并根据所选日期填充数据。

但是我得到的是空参考＆＃39;视图页面上出错。

我的观看页面

<h2>View Data in Database</h2>
<table><tr><td>
@using(Html.BeginForm("ViewPage1","Home"))
{
   <table><tr><td>From Date:</td>
              <td>@html.TextBoxFor(m=>m.FromDate,"{0:dd/MM/yyyy}")</td>
          </tr>
          <tr><td>To Date:</td>
              <td>@html.TextBoxFor(m=>m.ToDate,"{0:dd/MM/yyyy}")</td>
          </tr>
          <tr><td><input type="submit" Value="Show"></td>
              <td><input type="submit" Value="Show"></td>
          </tr>
   </table>
   <div id="ShowDropBoxes">
   <table>
        <tr><td>@Html.CheckBox("Production Order:", new{id="ck1"})</td>
            <td>@Html.DropDownlistFor(m=>m.ProdNo, Model.ProdOrdList, "Select Production Order")</td>
        </tr>
         <tr><td>@Html.CheckBox("Part Number:", new{id="ck2"})</td>
            <td>@Html.DropDownlistFor(m=>m.PartNo, Model.PartNoList, "Select Part Number")</td>
        </tr>
         <tr><td>@Html.CheckBox("Status:", new{id="ck3"})</td>
            <td>@Html.DropDownlistFor(m=>m.StatusTxt, Model.StatusList, "Select Status")</td>
        </tr>
   </table>
   </div>

我的模型

  public class HomeModel
  {
      public DateTime FromDate {get; set; }
      public DateTime ToDate {get; set; }
      public string ProdNo {get; set; }
      public string PartNo {get; set; }
      public int status {get; set; }
      public System.Web.Mvc.SelectList ProdNoList {get; set; }
      public System.Web.Mvc.SelectList PartNoList {get; set; }
      public System.Web.Mvc.SelectList StatusList {get; set; }
  }

控制器是： -

  public class HomeController: Controller
  {
       Repository List_in_Repository = new Repository();

       public ActionResult ViewPage1()
       {
           return View();
       }
       [HttpPost]
       public ActionResult ViewPage(HomeModel model)
       {
             string fromdate = model.FromDate.Tostring("yyyyMMdd");
             string todate = model.ToDate.Tostring("yyyyMMdd");
             model.ProdNoList = new SelectList(List_in_Repository.GetProductionOrders(fromdate,todate));
             model.PartNoList= new SelectList(List_in_Repository.GetPartNumbers(fromdate,todate));
             model.StatusList = new SelectList(List_in_Repository.GetStatus(fromdate,todate));
            return View(model);
       }
   }

Answer 1

您的GET方法不会为属性$GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['realurl'] = array ( '_DEFAULT' => array ( 'init' => array ( 'enableCHashCache' => '1', 'appendMissingSlash' => 'ifNotFile', 'enableUrlDecodeCache' => '1', 'enableUrlEncodeCache' => '1', ), 'redirects' => array ( ), 'preVars' => array ( '0' => array ( 'GETvar' => 'no_cache', 'valueMap' => array ( 'nc' => '1', ), 'noMatch' => 'bypass' ), '1' => array ( 'GETvar' => 'L', 'valueMap' => array ( 'de' => '0', 'en' => '1', 'cs' => '2' ), 'noMatch' => 'bypass' ), '2' => array ( 'GETvar' => 'lang', 'valueMap' => array ( 'de' => 'de', ), 'noMatch' => 'bypass', ), ), 'pagePath' => array ( 'type' => 'user', 'userFunc' => 'EXT:realurl/class.tx_realurl_advanced.php:&tx_realurl_advanced->main', 'spaceCharacter' => '-', 'languageGetVar' => 'L', 'expireDays' => '7', ), 'fixedPostVars' => array ( 'newsDetailConfiguration' => array( array( 'GETvar' => 'tx_news_pi1[action]', 'valueMap' => array( 'detail' => '', ), 'noMatch' => 'bypass' ), array( 'GETvar' => 'tx_news_pi1[controller]', 'valueMap' => array( 'Legamaster' => '', ), 'noMatch' => 'bypass' ), array( 'GETvar' => 'tx_news_pi1[news]', 'lookUpTable' => array( 'table' => 'tx_news_domain_model_news', 'id_field' => 'uid', 'alias_field' => 'title', 'addWhereClause' => ' AND NOT deleted', 'useUniqueCache' => 1, 'useUniqueCache_conf' => array( 'strtolower' => 1, 'spaceCharacter' => '-' ), 'languageGetVar' => 'L', 'languageExceptionUids' => '', 'languageField' => 'sys_language_uid', 'transOrigPointerField' => 'l10n_parent', 'autoUpdate' => 1, 'expireDays' => 180, ) ) ), 'newsCategoryConfiguration' => array( array( 'GETvar' => 'tx_news_pi1[overwriteDemand][categories]', 'lookUpTable' => array( 'table' => 'sys_category', 'id_field' => 'uid', 'alias_field' => 'title', 'addWhereClause' => ' AND NOT deleted', 'useUniqueCache' => 1, 'useUniqueCache_conf' => array( 'strtolower' => 1, 'spaceCharacter' => '-' ) ) ) ), 'newsTagConfiguration' => array( array( 'GETvar' => 'tx_news_pi1[overwriteDemand][tags]', 'lookUpTable' => array( 'table' => 'tx_news_domain_model_tag', 'id_field' => 'uid', 'alias_field' => 'title', 'addWhereClause' => ' AND NOT deleted', 'useUniqueCache' => 1, 'useUniqueCache_conf' => array( 'strtolower' => 1, 'spaceCharacter' => '-' ) ) ) ), ), 'postVarSets' => array ( '_DEFAULT' => array ( 'article' => array( array( 'GETvar' => 'tx_news_pi1[action]', 'noMatch' => 'bypass' ), array( 'GETvar' => 'tx_news_pi1[controller]', 'noMatch' => 'bypass' ), array( 'GETvar' => 'tx_news_pi1[year]', ),，SelectList和ProdNoList初始化PartNoList，因此当您尝试在StatusList中访问它们时抛出异常。

你GET方法需要使用空列表添加初始值（例如使用@Html.DropDownlistFor(m => m.ProdNo, Model.ProdOrdList ...)）

当您最初显示视图时，您不清楚如何“隐藏”下拉列表，但您应该考虑在POST方法中设置为Enumerable.Empty<T>()的视图模型属性（bool DisplayDropDowns）在返回视图之前。然后你可以使用

检查值

true

这意味着@if(Model.DisplayDropDowns) { .... // render dropdowns }不需要在GET方法中初始化，因为SelectList块中的代码永远不会被执行。

另请注意，POST方法应包含if

从同一视图中获取这些值后，从控制器传递值

1 个答案: