c# - 模型为空？

Question

我读过很多关于 null 模型的类似帖子，但我的案例非常非常简单，Create 操作上的模型仍然是 null。我究竟做错了什么？？？

情况是这样的:一个主视图，内部有两个强类型的部分 View ，每个 View 都绑定(bind)到主模型的一个公共(public)属性。任何帮助表示赞赏。模型:

public class SimpleModel1
{
    public IEnumerable<string> SomeStrings1 { get; set; }
}

public class SimpleModel2
{
    public IEnumerable<string> SomeStrings2 { get; set; }
}

public class ComplexModel
{
    public SimpleModel1 model1 { get; set; }
    public SimpleModel2 model2 { get; set; }
    public IEnumerable<string> SomeStringsComplex { get; set; }
}

他 Controller :

public ActionResult Create()
    {
        ComplexModel complex = new ComplexModel();
        complex.model1 = new SimpleModel1();
        complex.model1.SomeStrings1 = new List<string> { "a1", "a2", "a3"};

        complex.model2 = new SimpleModel2();
        complex.model2.SomeStrings2 = new List<string> { "b1", "b2", "b3" };

        complex.SomeStringsComplex = new List<string> { "c1", "c2", "c3" };
        return View(complex);
    }

    [HttpPost]
    public ActionResult Create(ComplexModel model)
    {
        if (ModelState.IsValid)
        {
            var test = model.SomeStringsComplex;
        }
        return View();
    }

观看次数:2 个强大的局部 View ——每个 View 都用于模型

<%@ Control Language="C#"     
Inherits="System.Web.Mvc.ViewUserControl<MvcApp1.Models.SimpleModel2>" %>

<fieldset>
    <legend>Fields</legend>
    <% foreach (string item in Model.SomeStrings2)
            {%>
            <p>
            <label for="Title">Item Title:</label>
            <%= Html.TextBox(item,item)%>               
            </p>
            <%
            }
         %>
</fieldset>

1个主视图:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master"
    Inherits="System.Web.Mvc.ViewPage<MvcApp1.Models.ComplexModel>" %>

<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
 Create
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

<h2>Create</h2>
 <% using (Html.BeginForm()) {%>
 <fieldset>
<div> Own values
<% foreach (string item in Model.SomeStringsComplex)
            {%>
            <p>
            <label for="Title">Item Title:</label>
            <%= Html.TextBox(item,item) %>          
            </p>
            <%
            }
         %>
</div>
<div>Simple values 1
<%Html.RenderPartial("SimpleModelView1", this.ViewData.Model.model1, new ViewDataDictionary()); %>
</div>

<div>Simple values 2
<%Html.RenderPartial("SimpleModelView2", Model.model2, new ViewDataDictionary()); %>
</div>
<p>
            <input type="submit" value="Create" />
        </p>
</fieldset>
 <% } %>

Answer 1

我要大胆地说，在将 ComplexModel 发回服务器时，您的模型验证失败

您的模型验证根本不必失败。您没有从 if block 中返回任何内容，因此您总是返回一个没有关联模型的 View :

if (ModelState.IsValid)
{
    var test = model.SomeStringsComplex;
}
return View(); // View is called with no Model data

根据您的代码判断，这会导致 Create View 在没有模型的情况下被实例化。这可以很简单地解决:

[HttpPost]
public ActionResult Create(ComplexModel model)
{
    if (ModelState.IsValid)
    {
        var test = model.SomeStringsComplex;
        // Do something to Create the object

        RedirectToAction("Index");
    }

    // Model State is invalid, return so the user can correct
    return View(model);
}