MVC - 列表中的 ICollection 在开机自检时不会返回到控制器

Question

在我的编辑屏幕中，我似乎无法在POST时获得模型中的ICollection返回到控制器。为了简单起见，有两个模型，一个Pattern表：

[Table("Pattern")]
public partial class Pattern
{
    public Pattern()
    {
        PatternFeatureAssociations = new HashSet<PatternFeatureAssociation>();
    }
    [Key]
    public int PkID { get; set; }
    [Required]
    public string PatternNumber { get; set; }
    public DateTime? CreatedOn { get; set; }
    public int? CrearedBy { get; set; }
    public DateTime? UpdatedOn { get; set; }
    public int? UpdatedBy { get; set; }
    public virtual ICollection<PatternFeatureAssociation> PatternFeatureAssociations { get; set; }
}

和PatternFeatureAssociation表：

[Table("PatternFeatureAssociation")]
public partial class PatternFeatureAssociation
{
    [Key]
    public int PkID { get; set; }
    public int PatternID { get; set; }
    public int FeatureName { get; set; }
    public int FeatureDesc { get; set; }
    public DateTime CreatedOn { get; set; }
    public int CreatedBy { get; set; }
    public DateTime? UpdatedOn { get; set; }
    public int? UpdatedBy { get; set; }
    public virtual Pattern Pattern { get; set; }
}

然后我有一个包含以下内容的ViewModel：

public class EditingViewModel
{
    public List<Pattern> patterns { get; set; }
    other values...
}

我的视图（这是部分版本）然后从ViewModel:离开

@model TEST.ViewModels.EditingViewModel
@using (Html.BeginForm("Edit", "Patterns", FormMethod.Post))
{
<input class="btnSave" type="submit" value="Save Changes" />
<br /><br />
for (int s = 0; s < Model.patterns.Count; s++)
{
    @Html.HiddenFor(modelItem => Model.patterns[s].PatternNumber)
    @Html.HiddenFor(modelItem => Model.patterns[s].PkID)
    <p><b>Pattern Number: </b>@Html.DisplayFor(modelItem => Model.patterns[s].PatternNumber)</p>
    @foreach (var item in Model.patterns[s].PatternFeatureAssociations)
    { 
        @Html.HiddenFor(modelItem => item.PkID)
        @Html.HiddenFor(modelItem => item.PatternID)
        <h3>Feature Name</h3>
        <div>@Html.EditorFor(modelItem => item.FeatureName)</div>
        <h3>Feature Description</h3>
        <div>@Html.EditorFor(modelItem => item.FeatureDesc)</div>               
    }
}  
}

但是，当我单击"保存"并返回到控制器时，ViewModel不会返回PatternFeatureAssociations数据。在获取视图的过程中，数据确实全部通过。

    [HttpPost]
    public ActionResult Edit(EditingViewModel searchedit)
    {
        return View();
    }

Answer 1

您需要使用for循环而不是foreach:进行索引

     @for(var i = 0; i < Model.patterns[s].PatternFeatureAssociations; i++)
        { 
            @Html.HiddenFor(modelItem => Model.patterns[s].PatternFeatureAssociations[i].PkID)
            @Html.HiddenFor(modelItem => Model.patterns[s].PatternFeatureAssociations[i].PatternID)        
            <h3>Feature Name</h3>
            <div>@Html.EditorFor(modelItem => Model.pattern    s[s].PatternFeatureAssociations[i].FeatureName)</div>    
            <h3>Feature Description</h3>
            <div>@Html.EditorFor(modelItem => Model.patterns[s].PatternFeatureAssociations[i].FeatureDesc)</div>               
    }

这将确保使用模型绑定器所期望的预期命名约定生成相关输入。

模型绑定到列表