entity-framework - 使用 Entity Framework 处理并发的最佳方式

Question

我正在使用 Entity Framework 4.1。处理与 Entity Framework 并发的最佳方法是什么。是否有内置功能可以在 Entity Framework 中处理它？
我可以不向表中添加额外的列以保持行版本吗？

Answer 1

您可以在表中设置一个名为 RowVersion 的列，并告诉 Entity Framework 您希望该列包含在所有 UPDATE 和 DELETE 语句的 where 子句中。然后确保为所有更改的实体增加此字段。我是这样做的:

//make all entities that need concurrency implement this and have RowVersion field in database
public interface IConcurrencyEnabled
{
    int RowVersion { get; set; }
}
public class MyDbContext : DbContext
{
    public override int SaveChanges()
    {
        foreach(var dbEntityEntry in ChangeTracker.Entries().Where(x => x.State == EntityState.Added || x.State == EntityState.Modified))
        {
            IConcurrencyEnabled entity = dbEntityEntry.Entity as IConcurrencyEnabled;
            if (entity != null)
            {
                entity.RowVersion = entity.RowVersion + 1;
            }
        }
        return base.SaveChanges();
    }
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        //do all your custom model definition but have the following also:
        modelBuilder.Entity<myEntity>().Property(x => x.RowVersion).IsConcurrencyToken();
    }
}