EF .NET 6 Data Annotations with database-first: cannot make annotations work

Question

Here's a model class (generated by scaffolding, nothing changed):

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

namespace EFDBFirst.Models
{
    public partial class Product
    {
        public Product()
        {
            OrderDetails = new HashSet<OrderDetail>();
        }

        public int ProductId { get; set; }
        public string ProductName { get; set; } = null!;
        public int? SupplierId { get; set; }
        public int? CategoryId { get; set; }        
        public string? QuantityPerUnit { get; set; }
        public decimal? UnitPrice { get; set; }
        public short? UnitsInStock { get; set; }
        public short? UnitsOnOrder { get; set; }
        public short? ReorderLevel { get; set; }
        public bool Discontinued { get; set; }

        public virtual Category? Category { get; set; }
        public virtual ICollection<OrderDetail> OrderDetails { get; set; }
    }
}

In order to preserve data annotation attributes after running scaffold-dbcontext, I assumed I would

1. Create a Metadata class, like so:

using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Diagnostics;

namespace EFDBFirst.Models
{    
    public partial class ProductMetadata
    {
        [Required(ErrorMessage = @"Qty/Unit is required")]
        [Display(Name ="QPU")]
        public string? QuantityPerUnit { get; set; }
    }
}

2. Create a partial Product class where I link the metadata class:

using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

namespace EFDBFirst.Models
{
    [MetadataType(typeof(ProductMetadata))]
    public partial class Product
    {
    }
}

But the display name doesn't show, and the required attribute isn't enforced.

Things I've already done:

• Clean and Rebuild
• Cleared the browser cache AND tried a different browser
• Close and re-open Visual Studio 2022
• Ensured that the namespace and class accessibility match exactly

BTW, if I add the attribute directly into the original model class, everything works as expected.

Any ideas? I can't for the life of me figure out what's (not) going on here....

Answer 1

MetadataType is outdated, and we shall use ModelMetadataType instead. Get OP's confirmation that it can solve the issue.