ASP.NET MVC模型绑定外键关系

这是我的观点-这是一个自定义模型绑定器,当被要求获取PropertyValue时,它会查看该属性是否是我的模型程序集中的对象,并具有IRepository<&燃气轮机;在我的NInject IKernel注册。如果它可以从Ninject获取IRepository,它将使用它来检索外键对象。

public class ForeignKeyModelBinder : System.Web.Mvc.DefaultModelBinder
{
    private IKernel serviceLocator;

    public ForeignKeyModelBinder( IKernel serviceLocator )
    {
        Check.Require( serviceLocator, "IKernel is required" );
        this.serviceLocator = serviceLocator;
    }

    /// <summary>
    /// if the property type being asked for has a IRepository registered in the service locator,
    /// use that to retrieve the instance.  if not, use the default behavior.
    /// </summary>
    protected override object GetPropertyValue( ControllerContext controllerContext, ModelBindingContext bindingContext,
        PropertyDescriptor propertyDescriptor, IModelBinder propertyBinder )
    {
        var submittedValue = bindingContext.ValueProvider.GetValue( bindingContext.ModelName );
        if ( submittedValue == null )
        {
            string fullPropertyKey = CreateSubPropertyName( bindingContext.ModelName, "Id" );
            submittedValue = bindingContext.ValueProvider.GetValue( fullPropertyKey );
        }

        if ( submittedValue != null )
        {
            var value = TryGetFromRepository( submittedValue.AttemptedValue, propertyDescriptor.PropertyType );

            if ( value != null )
                return value;
        }

        return base.GetPropertyValue( controllerContext, bindingContext, propertyDescriptor, propertyBinder );
    }

    protected override object CreateModel( ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType )
    {
        string fullPropertyKey = CreateSubPropertyName( bindingContext.ModelName, "Id" );
        var submittedValue = bindingContext.ValueProvider.GetValue( fullPropertyKey );
        if ( submittedValue != null )
        {
            var value = TryGetFromRepository( submittedValue.AttemptedValue, modelType );

            if ( value != null )
                return value;
        }

        return base.CreateModel( controllerContext, bindingContext, modelType );
    }

    private object TryGetFromRepository( string key, Type propertyType )
    {
        if ( CheckRepository( propertyType ) && !string.IsNullOrEmpty( key ) )
        {
            Type genericRepositoryType = typeof( IRepository<> );
            Type specificRepositoryType = genericRepositoryType.MakeGenericType( propertyType );

            var repository = serviceLocator.TryGet( specificRepositoryType );
            int id = 0;
#if DEBUG
            Check.Require( repository, "{0} is not available for use in binding".FormatWith( specificRepositoryType.FullName ) );
#endif
            if ( repository != null && Int32.TryParse( key, out id ) )
            {
                return repository.InvokeMethod( "GetById", id );
            }
        }

        return null;
    }

    /// <summary>
    /// perform simple check to see if we should even bother looking for a repository
    /// </summary>
    private bool CheckRepository( Type propertyType )
    {
        return propertyType.HasInterface<IModelObject>();
    }

}

显然,您可以用Ninject替换DI容器和您自己的存储库类型。

<%= Html.DropDownList( "ManufacturerID",
        (IEnumerable<SelectListItem>)ViewData["Manufacturers"] ) %>

具有

ViewData["Manufacturers"] = db.Manufacturers
                              .Select( m => new SelectListItem
                                            {
                                               Text = m.Name,
                                               Value = m.ManufacturerID
                                            } )
                               .ToList();

public JsonResult Save(int id,
                       [Bind(Include="Name, Description, ManufacturerID")]Car car)

也许这是一个比较晚的版本,但您可以使用自定义模型绑定器来实现这一点。通常我会用与@tvanofosson相同的方法来做,但我有一个案例,我将UserDetails添加到AspNetMembershipProvider表中。因为我也只使用POCO(并从EntityFramework映射它),所以我不想使用id,因为从业务角度来看它是不合理的,所以我创建了一个模型,只用于添加/注册用户。此模型具有用户的所有属性以及角色属性。我想将角色的文本名称绑定到它的RoleModel表示。基本上我就是这么做的:

public class RoleModelBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        string roleName = controllerContext.HttpContext.Request["Role"];

        var model = new RoleModel
                          {
                              RoleName = roleName
                          };

        return model;
    }
}

ModelBinders.Binders.Add(typeof(RoleModel), new RoleModelBinder());

<%= Html.DropDownListFor(model => model.Role, new SelectList(Model.Roles, "RoleName", "RoleName", Model.Role))%>

我希望这对你有帮助。