.net-coreentity-framework-coreblazoref-code-firstentity-framework-migrations

.NET Core / Blazor model attribute that doesn't get persisted to database


I have a model in my Blazor app that I want to create a "transitory" attribute for. This attribute is used internally in the app, but I do not want to persist it to the database.

However, when I change my model, it seems that the build process wants to create a database migration and change the database structure, adding the new attribute.

Is there a way to add a non-persistent attribute to the model, that will be ignored for database writes, but can be populated when the model is being handled in the app?


Solution

  • To create attributes on your models without worrying about EF Core automatically mapping the attributes to column in the DB or create migrations, you can annotate these attributes with the [NotMapped] annotation. This also works at the class level to mark the entire entity as not mapped to a DB table:

    public class Foo
    {
        public int Id { get; set; }
        public int SomeValue { get; set; }
    
        // Field will not be mapped to a DB Entity
        [NotMapped]
        public int Priority {get; set; }
    
        public DateTime CreatedOn { get; set; }
    }
    
    // Class will not be mapped to a DB Entity
    [NotMapped]
    public class Bar
    {
        public int Id { get; set; }
        public int SomeValue { get; set; }
        public DateTime CreatedOn { get; set; }
    }
    

    See also: exclude-property-if-column-is-not-in-database and learnentityframeworkcore.com/notmapped