elena-kim / study-efcore

Study EntityFramework Core

Docs

• Ignoring a class property in Entity Framework 4.1 Code First

  NotMapped Attribute

  public class Customer
  {
      public int CustomerID { set; get; }
      public string FirstName { set; get; } 
      public string LastName { set; get; } 
      [NotMapped]
      public int Age { set; get; }
  }

  OnModelCreating function

  public class SchoolContext : DbContext
  {
      public SchoolContext(DbContextOptions<SchoolContext> options) : base(options)
      {
      }
      
      protected override void OnModelCreating(ModelBuilder modelBuilder)
      {
          modelBuilder.Entity<Customer>().Ignore(t => t.FullName);
          base.OnModelCreating(modelBuilder);
      }
      
      public DbSet<Customer> Customers { get; set; }
  }

• Entity Framework Extensions

  UpdateFromQuery

  // UPDATE all customers that are inactive for more than two years
  var date = DateTime.Now.AddYears(-2);
  context.Customers
      .Where(x => x.IsActive && x.LastLogin < date)
      .UpdateFromQuery(x => new Customer {IsActive = false});
  
  // UPDATE customers by id
  context.Customers.Where(x => x.ID == userId).UpdateFromQuery(x => new Customer {IsActive = false});

  DeleteFromQuery

  // DELETE all customers that are inactive
  context.Customers.Where(x => !x.IsActive).DeleteFromQuery();
  
  // DELETE customers by id
  context.Customers.Where(x => x.ID == userId).DeleteFromQuery();

  Performance Comparisons

  Operations	1,000 Entities	2,000 Entities	5,000 Entities
  SaveChanges	1,000 ms	2,000 ms	5,000 ms
  UpdateFromQuery	1 ms	1 ms	1 ms
  DeleteFromQuery	1 ms	1 ms	1 ms

• EF-Core ORM