Entity framework 4 EF 4 CTP 5保存多对多导航属性

我使用的是EF4 CTP5，无法将记录保存回数据库。我有Contact和ContactType实体。正如文章标题所述，我在表之间设置了多对多导航属性

问题在于验证ContactType值。ModelState.IsValid为false，因为它无法将从表单（ContactType id的字符串数组）传回的值转换为ContactType对象

波科氏

public partial class Contact
{
    public Contact()
    {            
        this.ContactTypes = new HashSet<ContactType>();
    }

    // Primitive properties
    public int ContactId { get; set; }
    public string ContactName { get; set; }

    // Navigation properties
    public virtual ICollection<ContactType> ContactTypes { get; set; }
}

public partial class ContactType
{
    public ContactType()
    {
        this.Contacts = new HashSet<Contact>();
    }

    // Primitive properties
    public int ContactTypeId { get; set; }
    public string Name { get; set; }

    // Navigation properties
    public virtual ICollection<Contact> Contacts { get; set; }
}

看法

因此，问题似乎很清楚，但我似乎找不到解决方案。我已尝试手动将ContactType id转换为ContactType对象，并将其添加到传递到编辑函数（称为“Contact”）的Contact对象中：

但这并没有起作用。我还使用

ModelState.SetModelValue("ContactTypes", val);

这也不管用。我觉得我缺少了一些基本的东西。有什么想法吗

---

谢谢，Steve

在这方面做了更多的工作之后，我找到了一个解决办法。基本上，我必须忽略验证错误，然后手动删除现有的ContactType，然后添加用户选择的ContactType。我确实尝试为Contact.ContactTypes属性构建自定义验证器，但ContactType对象始终传递给该方法；我我从未见过字符串数组。无可否认，这是我构建的第一个自定义验证器，所以可能我遗漏了一些东西

不管怎样，我最终得到的编辑方法是：

//
// POST: /Contact/Edit/5
[HttpPost]
public virtual ActionResult Edit(Contact contact)
{
    // clear up ModelState.IsValid for contact type
    ModelState.Remove("ContactTypes");

    if(ModelState.IsValid)
    {
        // remove all contact types for contact
        Contact dummy = context.Contacts.Single(c => c.ContactId == contact.ContactId);
        if(dummy.ContactTypes.Count > 0)
        {
            dummy.ContactTypes.Clear();
            context.Entry(dummy).State = EntityState.Modified;
            context.SaveChanges();
        }
        context.Detach(dummy);
        context.Contacts.Attach(contact);

        // add currently selected contact types, then save
        string[] ids = this.HttpContext.Request.Form["ContactTypes"].Split(',');
        for(int i = 0; i< ids.Length; i++)
        {
            int x = Convert.ToInt32(ids[i]);
            ContactType selectedType = context.ContactTypes.Single(t => t.ContactTypeId == x);
            contact.ContactTypes.Add(selectedType);                    
        }
        context.Entry(contact).State = EntityState.Modified;
        context.SaveChanges();

        ViewBag.Message = "Save was successful.";
    }

    ViewData["ContactTypes"] = contact.ContactTypes.Select(t => t.ContactTypeId);
    ViewData["ContactTypesAll"] = GetTypesList();            
    return View(contact);
}

ModelState.Values.ElementAt(2).Value
{System.Web.Mvc.ValueProviderResult}
    AttemptedValue: "5"
    Culture: {en-US}
    RawValue: {string[1]}

ModelState.Values.ElementAt(2).Errors[0]
{System.Web.Mvc.ModelError}
    ErrorMessage: ""
    Exception: {"The parameter conversion from type 'System.String' to type 'ProjectObjects.ContactType' failed because no type converter can convert between these types."}

contact.ContactTypes.Clear();
string[] ids = this.HttpContext.Request.Form["ContactTypes"].Split(',');
for(int i = 0; i< ids.Length; i++)
{
    int x = Convert.ToInt32(ids[i]);
    ContactType selectedType = context.ContactTypes.Single(t => t.ContactTypeId == x);
    contact.ContactTypes.Add(selectedType);
}

context.ChangeTracker.DetectChanges();

ModelState.SetModelValue("ContactTypes", val);

//
// POST: /Contact/Edit/5
[HttpPost]
public virtual ActionResult Edit(Contact contact)
{
    // clear up ModelState.IsValid for contact type
    ModelState.Remove("ContactTypes");

    if(ModelState.IsValid)
    {
        // remove all contact types for contact
        Contact dummy = context.Contacts.Single(c => c.ContactId == contact.ContactId);
        if(dummy.ContactTypes.Count > 0)
        {
            dummy.ContactTypes.Clear();
            context.Entry(dummy).State = EntityState.Modified;
            context.SaveChanges();
        }
        context.Detach(dummy);
        context.Contacts.Attach(contact);

        // add currently selected contact types, then save
        string[] ids = this.HttpContext.Request.Form["ContactTypes"].Split(',');
        for(int i = 0; i< ids.Length; i++)
        {
            int x = Convert.ToInt32(ids[i]);
            ContactType selectedType = context.ContactTypes.Single(t => t.ContactTypeId == x);
            contact.ContactTypes.Add(selectedType);                    
        }
        context.Entry(contact).State = EntityState.Modified;
        context.SaveChanges();

        ViewBag.Message = "Save was successful.";
    }

    ViewData["ContactTypes"] = contact.ContactTypes.Select(t => t.ContactTypeId);
    ViewData["ContactTypesAll"] = GetTypesList();            
    return View(contact);
}

public void Detach(object entity) 
{
    ((System.Data.Entity.Infrastructure.IObjectContextAdapter)this).ObjectContext.Detach(entity);
}