MVC和实体框架中的嵌套查找

Question

I'm running into a problem with a project I'm working on. I'm relatively new to MVC so I'm hoping this is something simple!

I'm trying to perform an edit on an object, but the object in question has a couple of ICollections that it can't seem to bind to.

The class I'm trying to update is called 'Key', and the definition is:

public partial class Key
{
    public Key()
    {
        this.KeyFields = new HashSet<KeyField>();
        this.KeyServices = new HashSet<KeyService>();
    }

    public int ID { get; set; }
    public System.Guid APIKey { get; set; }
    public string SiteURL { get; set; }
    public bool Active { get; set; }
    public virtual ICollection<KeyField> KeyFields { get; set; }
    public virtual ICollection<KeyService> KeyServices { get; set; }
}

The KeyField and KeyService classes are:

public partial class KeyField
{
    public int ID { get; set; }
    public int SiteKey { get; set; }
    public int Field { get; set; }
    public bool Active { get; set; }

    public virtual Field Field1 { get; set; }
    public virtual Key Key { get; set; }
}

public partial class KeyService
{
    public int ID { get; set; }
    public int SiteKey { get; set; }
    public int Service { get; set; }
    public bool Active { get; set; }

    public virtual Key Key { get; set; }
    public virtual Service Service1 { get; set; }
}

The related Service class is:

public partial class Service
{
    public Service()
    {
        this.KeyServices = new HashSet<KeyService>();
    }

    public int ID { get; set; }
    public string Name { get; set; }
    public int Service_View { get; set; }

    public virtual ICollection<KeyService> KeyServices { get; set; }
    public virtual View View { get; set; }

    [NotMapped]
    public bool IsSelected { get; set; }
}

and the related Field class is:

public partial class Field
{
    public Field()
    {
        this.KeyFields = new HashSet<KeyField>();
    }

    public int ID { get; set; }
    public string Title { get; set; }
    public int Field_View { get; set; }

    public virtual View View { get; set; }
    public virtual ICollection<KeyField> KeyFields { get; set; }

    [NotMapped]
    public bool IsSelected { get; set; }
}

The View is using a custom model called 'KeyDetailsModel'. It contains an instance of the 'Key' object and 2 IEnumerables. These are there so that I can output all the fields and services in the database into a list of checkboxes on the View. The fields and services that should be preselected on the View are ICollections in the Key class. the definition is:

public class KeyDetailsModel
{
    public Key Key { get; set; }
    public IEnumerable<Field> Fields { get; set; } 
    public IEnumerable<Service> Services { get; set; } 
}

The is the code in the controller that sets up the 'display' page:

    public ViewResult KeyDetails(int id)
    {
        var fieldChannel = new Repo<Field>();
        var serviceChannel = new Repo<Service>();

        //gets the key information
        var key = _keyChannel.GetById(id);

        //gets all the fields in the database
        var fields = fieldChannel.GetAll();

        //gets all the services in the database
        var services = serviceChannel.GetAll();

        //gets the KeyFields for the key, and sets the IsSelected flag for the related Field
        foreach (var f in fields)
        {
            var selectedField = (from sf in key.KeyFields
                                 where sf.ID == f.ID && sf.SiteKey == id
                                 select sf).FirstOrDefault();

            if (selectedField != null)
            {
                f.IsSelected = true;
            }
        }

        //gets the KeyServices for the key, and sets the IsSelected flag for the related Service
        foreach (var f in services)
        {
            var selectedService = (from ss in key.KeyServices
                                 where ss.ID == f.ID && ss.SiteKey == id
                                 select ss).FirstOrDefault();

            if (selectedService != null)
            {
                f.IsSelected = true;
            }
        }

        //create the model
        var KeyDetailsModel = new KeyDetailsModel
        {
            Fields = fields,
            Key = key,
            Services = services
        };

        return View(KeyDetailsModel);
    }

This is the method in the controller that will perform the edit:

    [HttpPost]
    public ActionResult KeyDetails(KeyDetailsModel KeyDetailsModel)
    {
        if (KeyDetailsModel != null && ModelState.IsValid)
        {
            return View(KeyDetailsModel);
        }
        else
        {
            return View(KeyDetailsModel);
        }
    }

Finally, the cshtml page is:

@model EdinburghNapier.EAWebLayer.Admin.Models.KeyDetailsModel

@{
   ViewBag.Title = "KeyDetails";
   Layout = "~/Views/Shared/_Layout.cshtml";
 }

<h2>Key Details</h2>

@using (Html.BeginForm("KeyDetails", "Key", FormMethod.Post))
{
<fieldset>
    <legend>Key</legend>

    <div class="display-label">
        @Html.DisplayNameFor(model => model.Key.APIKey)
    </div>
    <div class="display-field">
        @Html.EditorFor(model => model.Key.APIKey)
    </div>

    <div class="display-label">
        @Html.DisplayNameFor(model => model.Key.SiteURL)
    </div>
    <div class="display-field">
        @Html.EditorFor(model => model.Key.SiteURL)
    </div>

    <div class="display-label">
        @Html.DisplayNameFor(model => model.Key.Active)
    </div>
    <div class="display-field">
        @Html.EditorFor(model => model.Key.Active)
    </div>


    <div class="display-field">
        <ul>
            @foreach (var f in Model.Fields)
            {
                <li>
                    <input type="checkbox"
                           name="Key.KeyFields" value="@f.ID" id="Field_@f.ID"
                           checked="@f.IsSelected"/>
                    <label for="@f.ID">@f.Title</label>
                </li>
            }
        </ul>
    </div>

    <div class="display-field">
        <ul>
            @foreach (var f in Model.Services)
            {
                <li>
                    <input type="checkbox"
                   name="Key.KeyServices" value="@f.ID" id="Service_@f.ID"
                   checked="@f.IsSelected"/>
                    <label for="@f.ID">@f.Name</label>
                </li>
            }
        </ul>
    </div>
</fieldset>    
@Html.HiddenFor(model => model.Key.ID)
<input type="submit" value="Save"/>
}

What is happening when I submit the form is that the 'KeyFields' and 'KeyServices' properties of the 'Key' class in the 'KeyDetailsModel' are always 0. The edit screen doesn not seem to be able to bind the check box lists to the properties. One consequence of this is that the status of the ModelState is always false when I submit.

I've been bashing my head against a wall over this for a couple of days now, hope someone can help! I appreciate that I may have supplied too much code and too little explanation - please let me know if that's the case!

Answer 1

You are binding your checkboxes in incorrect way, you should read a bit more about it, you can check some article like this: http://haacked.com/archive/2008/10/23/model-binding-to-a-list.aspx/

Your code should be changed, so that each checkbox had an indexer in its name:

<div class="display-field">
    <ul>
        @for (var i = 0; i < Model.Fields.Count(); i++)
             {
            <li>
                <input type="checkbox"
                       name="@Html.NameFor(x=>x.Fields[i])" value="@Model.Fields[i].ID" id="@Html.IdFor(x=>x.Fields[i])"
                       checked="@Model.Fields[i].IsSelected" />
                <label for="@Html.NameFor(x=>x.Fields[i])">@Model.Fields[i].Title</label>
            </li>
        }
    </ul>
</div>

<div class="display-field">
    <ul>
        @for (var i = 0; i < Model.Services.Count(); i++)
                {
                <li>
                    <input type="checkbox"
                           name="@Html.NameFor(x=>x.Services[i])" value="@Model.Services[i].ID" id="@Html.IdFor(x=>x.Services[i])"
                           checked="@Model.Services[i].IsSelected" />
                    <label for="@Html.NameFor(x=>x.Services[i])">@Model.Services[i].Name</label>
                </li>
        }
    </ul>
</div>

You will also have to make your Services and Fields properties an array here:

public class KeyDetailsModel
{
    public Key Key { get; set; }
    public Field[] Fields { get; set; } 
    public Service[] Services { get; set; } 
}

Alternately, you can just use @Html.CheckBoxFor(x=>x.Fields[i].IsSelected inside the cycle, stick to Mvc Helpers, they really make the difference.