ViewModel在POST後部分爲空

Question

我有一個MVC 4應用程序，我有一個ViewModel，它有幾個集合。在POST期間，集合爲空，但其他字段已填充。附上代碼請幫忙。

視圖模型

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

namespace BAQueryTool.Models 
{ 
    public class QueryDefinition 
    { 
     [Key] 
     public int ID { get; set; } 
    [Display(Name = "Query Name")] 
    [MaxLength(32)] 
    [Required(ErrorMessage = "Query name is required.")] 
    public string Name { get; set; } 

    [Display(Name = "Query String")] 
    [Required(ErrorMessage = "Query string is required.")] 
    [DataType(DataType.MultilineText)] 
    [MaxLength(8192)] 
    public string QueryString { get; set; } 

    [NotMapped] 
    [Display(Name = "Query String")] 
    [MaxLength(175)] 
    public string QueryStringShort 
    { 
     get 
     { 
      string s = string.Empty; 

      if (this.QueryString != null) 
      { 
       s = this.QueryString.Trim(); 
       if (s.Length >= 172) 
       { 
        return this.QueryString.Substring(0, 172) + "..."; 
       } 
      } 

      return s; 
     } 
    } 

    [Display(Name = "Query Parameters")] 
    public virtual ICollection<QueryParameter> QueryParameters { get; set; } 
} 

public class RunQueryDefinition 
{ 
    public QueryDefinition QueryDefinition { get; set; } 

    [Display(Name = "Run Query Parameters")] 
    public virtual ICollection<RunQueryParameter> RunQueryParameters { get; set; } 
} 

}

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

namespace BAQueryTool.Models 
{ 
    public enum ParameterDataType 
    { 
     Date, String 
    } 
public class QueryParameter 
{ 
    [Key] 
    public int ID { get; set; } 

    public int QueryDefinitionID { get; set; } 

    [Display(Name = "Parameter Name")] 
    [Required(ErrorMessage = "Parameter name is required.")] 
    [MaxLength(32)] 
    public string Name { get; set; } 

    [Display(Name = "Parameter Type")] 
    [Required(ErrorMessage = "Parameter name is required.")] 
    public ParameterDataType DataType { get; set; } 
} 

public class RunQueryParameter : QueryParameter 
{ 
    [Display(Name = "Parameter Value")] 
    [Required(ErrorMessage = "Parameter name is required.")] 
    public string Value { get; set; } 
} 

}

控制器

`  `// GET: /QueryDefinition/Run/5 
     public ActionResult Run(int? id) 
     { 
      if (id == null) 
      { 
       return new HttpStatusCodeResult(HttpStatusCode.BadRequest); 
      } 
      QueryDefinition querydefinition = db.QueryDefinitions.Find(id); 
      if (querydefinition == null) 
      { 
       return HttpNotFound(); 
      } 
      RunQueryDefinition runQueryDefinition = new RunQueryDefinition(); 
      runQueryDefinition.QueryDefinition = querydefinition; 
      runQueryDefinition.RunQueryParameters = new List<RunQueryParameter> { }; 
      foreach (var param in querydefinition.QueryParameters) 
      { 
       RunQueryParameter rqp = new RunQueryParameter(); 
       rqp.ID = param.ID; 
       rqp.QueryDefinitionID = param.QueryDefinitionID; 
       rqp.Name = param.Name; 
       rqp.DataType = param.DataType; 
       rqp.Value = Convert.ToString(DateTime.Now.ToShortDateString()); 
       runQueryDefinition.RunQueryParameters.Add(rqp); 
      } 
      return View(runQueryDefinition); 
     } 

     [HttpPost] 
     [ValidateAntiForgeryToken] 
     public ActionResult Run(RunQueryDefinition parameterList) 
     { 
      DateTime BeginDate; 
      DateTime EndDate; 

      try 
      { 
       //QueryDefinition querydefinition = db.QueryDefinitions.Find(id); 

       if (ModelState.IsValid) 
       { 

        return RedirectToAction("Index"); 
       } 
      } 
      catch (RetryLimitExceededException) 
      { 
       //Log the error 
       ModelState.AddModelError("", "Unable to save changes. Try again, and if the problem persists see your system administrator."); 
      } 

      return View(); 
     } 

查看

@model BAQueryTool.Models.RunQueryDefinition 

@{ 
    ViewBag.Title = "Run Query"; 
} 

<h2>Run Query Definition '@Html.DisplayFor(model => model.QueryDefinition.Name)'</h2> 

@using (Html.BeginForm("Run", "QueryDefinition", FormMethod.Post, null)) 
{ 
    @Html.AntiForgeryToken() 

    <div class="form-horizontal"> 
     <hr /> 
     <dl class="dl-horizontal"> 
      <dt> 
       @Html.DisplayNameFor(model => model.RunQueryParameters) 
      </dt> 
      <dd> 
       <table class="table"> 
        <tr> 
         <th>Parameter Name</th> 
         <th>Parameter Data Type</th> 
         <th>Parameter Value</th> 
        </tr> 
        @foreach (var item in Model.RunQueryParameters) 
        { 
         <tr> 
          <td> 
           @Html.DisplayFor(modelItem => item.Name) 
          </td> 
          <td> 
           @Html.DisplayFor(modelItem => item.DataType) 
          </td> 
          <td> 
           @Html.EditorFor(modelItem => item.Value) 
          </td> 
         </tr> 
        } 
       </table> 
      </dd> 

     </dl> 

     <div class="form-group"> 
      <div class="col-md-offset-1 col-md-10"> 
       <input type="submit" value="Run Query" class="btn btn-default" /> 
      </div> 
     </div> 
    </div> 
} 

<div> 
    @Html.ActionLink("Back to List", "Index") 
</div> 

@section Scripts { 
    @Scripts.Render("~/bundles/jqueryval") 
} 

主要的類是QueryDefinition類。有一個列出所有查詢定義的索引頁面。當用戶點擊「運行」鏈接時，將生成運行頁面並使用QueryDefinitions填充ID。 QueryParameters集合也被填充以及RunQueryParameters集合。當用戶輸入列值的值並單擊運行查詢時，會發生POST。在調試中，我注意到RunQueryDefinitions parameterList參數沒有完全填充，特別是集合QueryParameters和RunQueryParameters。

有什麼建議嗎？

Answer 1

不要使用foreach循環，使用循環代替該集合的索引值可以得到發佈：

@for(int i = 0; i < Model.RunQueryParameters.Count; i++) 
        { 
         <tr> 
          <td> 
           @Html.DisplayFor(modelItem => Model.RunQueryParameters[i].Name) 
          </td> 
          <td> 
           @Html.DisplayFor(modelItem => Model.RunQueryParameters[i].DataType) 
          </td> 
          <td> 
           @Html.EditorFor(modelItem => Model.RunQueryParameters[i].Value) 
          </td> 
         </tr> 
        } 

瞭解如何在this article.