Web API Custom ModelBinder Required child object

Question

I am using ASP.NET Web API 2,and I'm trying to validate this child object from my request

the [DataAnnotation Required] is working well on my parent object, but its not working when the a [required] property in child object is missing.

below the sample of my model

In the below posted data, when I'm trying to insert in the table [Users] using the below request (missed the DeviceName in the child object Devices), the [Devices] is not validated against the Data annotations. This means that I don't got an error in the ModelState indicates that the DeviceName field is required. Note: The User object is model binding and validation is working good.

Also the custom ModelBinder is not fired

Model:

[Serializable]
[Table("Users")]
public partial class Users
{
    [Key]
    [Column("ID")]
    public int ID { get; set; }

    [Required]
    [DataType(DataType.Text)]
    [Column("UserName")]
    public string UserName { get; set; }

    public virtual ICollection<UserDevice> UserDevices { get; set; }
}

[Serializable]
[Table("Users_Devices")]
public partial class UserDevice
{
    [Key]
    [Column("ID")]
    public int ID { get; set; }

    [Column("DeviceName")]
    [DataType(DataType.Text)]
    [Required]
    public string DeviceName { get; set; }

    [Column("DeviceDescription")]
    [DataType(DataType.Text)]
    [Required]
    public string DeviceName { get; set; }

    [Column("UserID", TypeName = "int")]
    public int UserID { get; set; }
    [ForeignKey("UserID")]
    public virtual Users User { get; set; }
}

Controller:

public async Task<IHttpActionResult> Post([ModelBinder(typeof(APIUsersModelBinder))] Users user)
    {
        if (!ModelState.IsValid)
            return BadRequest(ModelState);

        _db.Users.Add(user);
        await _db.SaveChangesAsync();

        return Created(user);
    }

Request Body:

{
    "UserName":"TestUser",
     "Devices":
        [{
            "DeviceDescription":"Description"
        }]
}

Thanks in advance.

Answer 1

After a lot of search I found that there is no other way than firing the validations manually as mentioned in this link

http://www.tsjensen.com/blog/post/2011/12/23/Custom+Recursive+Model+Validation+In+NET+Using+Data+Annotations.aspx