.net core default value when saving but identity info is different dbcontext

Question

On all my database tables i want to store the userid in a field called CreatedBy. I have a property on a base entity class for this. My db context class currently looks like this:

namespace Infrastructure.Data
{
    public class ManagementContext : DbContext
    {
        public ManagementContext(DbContextOptions<ManagementContext> options)
            : base(options)
        {
        }

        public DbSet<Department> Department { get; set; }        

        public override Task<int> SaveChangesAsync(bool acceptAllChangesOnSucess, CancellationToken cancellationToken = default(CancellationToken))
        {
            var AddedEntities = ChangeTracker.Entries().Where(E => E.State == EntityState.Added).ToList();

            AddedEntities.ForEach(E =>
            {
                E.Property("CreatedOn").CurrentValue = DateTime.UtcNow;
              //E.Property("CreatedBy").CurrentValue = ????
            });

            var EditedEntities = ChangeTracker.Entries().Where(E => E.State == EntityState.Modified).ToList();
            EditedEntities.ForEach(E =>
            {
                E.Property("LastModifiedOn").CurrentValue = DateTime.UtcNow;
            });
            return base.SaveChangesAsync(acceptAllChangesOnSucess, cancellationToken);
        }
    }
}

My identity user / info is in a different context (as seen in the ewebshop demo) How would i go about setting the value of CreatedBy? Should this be done elsewhere?

Answer 1

Based on the comment on your post, the CreatedBy column value always gets its value from the connected user so you need to do these steps:

Firstly, you need to configure the DI about how to get the current connected user like below into your ConfigureServices of Startup class:

services.AddScoped<IPrincipal>(
    provider => provider.GetService<IHttpContextAccessor>().HttpContext.User);

Secondly, inject an instance of IPrincipal into your DbContext like below:

public ManagementContext(DbContextOptions<ManagementContext> options, IPrincipal principal)
    : base(options)
{
    this.principal = principal;
}

Finally when setting the value of CreatedBy column you get the current user by finding it from the value of this.principal.Identity.Name .