[NotMapped] Attribute causes a cast error

[Letsion]

[NotMapped] Attribute causes a cast error with the MapIgnoreAnotationHandler.

Fix:
Write your Own Anotation Handler for NotMappedAttribute:

using System.ComponentModel.DataAnnotations.Schema;
using Detached.Mappers;
using Detached.Mappers.Annotations;
using Detached.Mappers.Types.Class;

namespace BOB.Backend.Common.AttributeHandlers
{
    public class NotMappedAnnotationHandler : AnnotationHandler<NotMappedAttribute>
    {
        public override void Apply(NotMappedAttribute annotation, MapperOptions mapperOptions, ClassType typeOptions, ClassTypeMember memberOptions)
        {
            memberOptions.Ignore(true);
        }
    }
}

[leonardoporro]

Hi Nico,
Yup, there was a missing handler over there.. removed in 7.1.2.
I thought we agreed not to stop mapping for [NotMapped] but only for [MapIgnore].

A better workardound would be options.AnnotationHandlers.Remove(typeof(NotMappedAttribute));

Anyway, you already know how to create your own handlers, so, excellent..

[Letsion]

The problem was, it should still map the properties with NotMapped, which are not in the database.
Now when I remove NotMapped from the AnnotationHandlers Dictornary, it wants to load and track the Ef Core, but they are not in the database = error.
Suggested solution:
For the NotMapped attribute, map the values from the DTo to the entity, but don't try to load/track them from the database.