如何在C＃中使用Entity Framework使用字符串值生成自动增量编号

Question

Is it possible to auto generate entity value using Entity Framework? For example a registration id such as 2015ACAD0001 - in this value, the first 4 digits show the year, the next 3 digits show any prefix according to requirement, and the remaining digits are auto increment no as per specific year and prefix

Answer 1

Yes, with a computed column:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Foo>()
        .Property(p => p.RegistrationId)
        .HasComputedColumnSql([SQL HERE]);
}

How to calculate the exact id is on you. Generally-speaking, it just needs to be a SQL expression that evaluates to the type of the column you're computing for, in this case: a string.