EF Core Data Attributes are not overwritten by ModelMetadataType attributes

Question

I have an EF Core partial class from our database table that includes data annotations, such as Required.

I also have a Metadata class and another partial that as far as I can tell 'should' be overwriting those EF annotations, but that is not happening.

snippet of EF class:

namespace Business  
{  
    public partial class Staff  
    {  
        [Key]  
        public int ID { get; set; }  
        [Required]  
        [StringLength(50)]  
        public string FirstName { get; set; }  
        [Required]  
        [StringLength(50)]  
        public string LastName { get; set; }  
    }  
}  

snippet of Metadata class:

namespace Business  
{  
    /// <summary>  
    /// The Staff object  
    /// </summary>  
    public class StaffMD  
    {  
        [DisplayName("ID")]  
        [Description("The unique key for a Staff")]  
        [Required(ErrorMessage = "ID is required")]  
        public int ID { get; set; }  
        [DisplayName("First Name")]  
        [Description("The First Name for a Staff")]  
        [Required(ErrorMessage = "First Name is required")]  
        [MaxLength(50, ErrorMessage = "First Name can only be {1} characters")]  
        public string FirstName { get; set; }  
        [DisplayName("Last Name")]  
        [Description("The Last Name for a Staff")]  
        [Required(ErrorMessage = "Last Name is required")]  
        [MaxLength(50, ErrorMessage = "Last Name can only be {1} characters")]  
        public string LastName { get; set; }  
    }  
  
    [ModelMetadataType(typeof(StaffMD))]  
    public partial class Staff  
    {  
    }  
}  

snippet of view:

@model Staff  
@using Business;  
  
@{  
    ViewData["Title"] = "Create - Staff";  
}  
  
@using (Html.BeginForm("Create", "Staff", null, FormMethod.Post, true, null))  
{  
    <p>  
        <div class="formContainer" id="formContainerParent">  
            <div class="formContainer-item">  
                <h2 class="formContainer-header" id="formHeadingOne">  
                    <label class="formContainer-headerContent">  
                        Create Staff  
                    </label>  
                </h2>  
                <div id="formContentOne" class="formContainer-body" aria-labelledby="formHeadingOne">  
                    <div class="formContainer-bodyContent">  
                        <div class="row">  
                            <div class="col-md-3">  
                                <div>  
                                    @Html.AccessibleRequiredLabelFor(model => model.FirstName, null, null, new { @class = "control-label" })  
                                </div>  
                                <div>  
                                    @Html.TextBoxFor(model => model.FirstName, null, new { @class = "form-control" })  
                                    @Html.ValidationMessageFor(model => model.FirstName)  
                                </div>  
                            </div>  
                            <div class="col-md-3">  
                                <div>  
                                    @Html.AccessibleRequiredLabelFor(model => model.LastName, null, null, new { @class = "control-label" })  
                                </div>  
                                <div>  
                                    @Html.TextBoxFor(model => model.LastName, null, new { @class = "form-control" })  
                                    @Html.ValidationMessageFor(model => model.LastName)  
                                </div>  
                            </div>  
                        </div>  
                    </div>  
                </div>  
            </div>  
        </div>  
    </p>  
}  

Image of application using 'default' Required message from EF core attribute

Answer 1

Hi @Daniel ,

The MetadataTypeAttribute attribute enables you to associate a class with a data-model partial class. In this associated class you provide additional metadata information that is not in the data model. So, if the data-model partial class (EF class) and associated class both sets the RequiredAttribute attribute, it will use the data-model partial class (EF class)'s RequiredAttribute attribute.

So, to use the ModelMetadataType's validation message, you can remove the DataAnnotations from the EF class:

 namespace Business  
 {  
     public partial class Staff  
     {  
         [Key]  
         public int ID { get; set; }   
         public string FirstName { get; set; }   
         public string LastName { get; set; }  
     }  
 }  

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Best regards,
Dillion