web-app-template/backend/app/app.Data/DatabaseContext.cs

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.ChangeTracking;
using app.Interface.Repositories;
using app.Model;
using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace app.Data
{
    public class DatabaseContext : DbContext, IUnitOfWork
    {
        public DatabaseContext(DbContextOptions<DatabaseContext> options) : base(options) { }

        public DbSet<AuthUser> AuthUsers { get; set; }

        public Task<int> SaveChangesAsync()
        {
            var changedList = ChangeTracker.Entries<IAutoGenerateDateFields>().Where(x => x.State == EntityState.Added || x.State == EntityState.Modified);
            foreach (var item in changedList)
            {
                item.Entity.LastModifiedOn = DateTime.UtcNow;
                if (item.State == EntityState.Added)
                    item.Entity.CreatedOn = DateTime.UtcNow;
            }
            return base.SaveChangesAsync();
        }

        public override int SaveChanges()
        {
            var changedList = ChangeTracker.Entries<IAutoGenerateDateFields>().Where(x => x.State == EntityState.Added || x.State == EntityState.Modified);
            foreach (var item in changedList)
            {
                item.Entity.LastModifiedOn = DateTime.UtcNow;
                if (item.State == EntityState.Added)
                    item.Entity.CreatedOn = DateTime.UtcNow;
            }
            return base.SaveChanges();
        }

        public override Task<int> SaveChangesAsync(CancellationToken cancellationToken = default(CancellationToken))
        {
            // Datum der letzten Änderung, etc. setzen
            DateTimeOffset now = DateTimeOffset.UtcNow;
            var changedList = ChangeTracker.Entries<IAutoGenerateDateFields>().Where(x => x.State == EntityState.Added || x.State == EntityState.Modified);
            foreach (var item in changedList)
            {
                item.Entity.LastModifiedOn = now;
                if (item.State == EntityState.Added)
                    item.Entity.CreatedOn = now;
            }
            return base.SaveChangesAsync();
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);

            modelBuilder.Entity<AuthUser>()
                .HasIndex(au => au.EMail)
                .IsUnique(true);

            modelBuilder.Entity<AuthUser>()
                .HasIndex(au => au.ConfirmationId)
                .IsUnique(true);

            modelBuilder.Entity<AuthUser>()
                .HasIndex(au => au.ForgotPasswordId)
                .IsUnique(true);
        }
    }
}