EF Core Fluent API, set IsRequired on all entities to generate a non-null db column - entity-framework

Question

I'm working on a Razor pages web app which works directly with a db context...yes this is not ideal but is what I'm stuck with for the time being.
In the data model, each object inherits from a base entity class containing audit data, e.g.:
public class BaseEntity
{
[Key]
public int Id { get; set; }
public DateTime CreatedOn { get; set; }
public string CreatedBy { get; set; }
...etc.
public class Table1 : BaseEntity
{
public string TestItemName { get; set; }
}
In the database, I want CreatedBy to be required (not null), but I don't want to use the [Required] attribute since this will trigger the UI to validate the CreatedBy column. I don't want to expose this column in the UI and instead have service code which updates all of the audit properties based on Add/Insert.
What I'm looking for is a way via Fluent API which will give me the column type in the db that I need, e.g. NVARCHAR(MAX) NOT NULL.
I can accomplish this in the OnModelCreating method in the dbcontext:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Table1>()
.Property(o => o.CreatedBy)
.IsRequired();
However this would require me to create a similar entry for every table in the model.
Is there code I can use in OnModelCreating which could accomplish this for all entities? Something like this (this is just pseudo-code, but looking to give an idea):
var entityTypes = modelBuilder.Model.GetEntityTypes().Select(o => o.GetType()).ToList();
entityTypes.ForEach(e =>
{
e.Property("CreatedBy").IsRequired();
});

Answer 1

Implement your entity configurations in discrete classes that implement IEntityTypeConfiguration. Your implementations should inherit from a base implementation that configures BaseEntity and the Configure method should be virtual with overriding implementations calling the base class' method:
public abstract class BaseEntityConfiguration<TEntity>
: IEntityTypeConfiguration<TEntity>
where TEntity : BaseEntity
{
public virtual void Configure(EntityTypeBuilder<TEntity> builder)
{
builder.Property(be => be.CreatedBy)
.IsRequired();
// etc
}
}
public class SomeEntityConfiguration : BaseEntityConfiguration<SomeEntity>
{
public override void Configure(EntityTypeBuilder<SomeEntity> builder)
{
// call base class method to configure BaseEntity properties
base.Configure(builder);
// configure remaining SomeEntity-specific properties/etc
builder.TestItemName.IsRequired();
}
}
You'll need to inform the model builder to use your configuration classes. For example, if your config classes are in the same assembly as your DbContext:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.ApplyConfigurationsFromAssembly(
typeof(YourDbContext).Assembly);
}