Add database trigger with Entity Framework Code First Migrations

Question

I use Entity Framework Migrations for code first to control my database model. It works charming and I can handle until now everything. But now I need to add one database tr

Answer 1

Recently I faced similar problem and didn't find a solution to not write sql manually. So I wrote a little package which allows to write migrations using Ef Core entity builder like this:

modelBuilder.Entity()
    .AfterInsert(trigger => trigger
        .Action(triggerAction => triggerAction
            .Upsert(transaction => new { transaction.UserId },
                insertedTransaction => new UserBalance { UserId = transaction.UserId, Balance = insertedTransaction.Sum },
                (insertedTransaction, oldBalance) => new UserBalance { Balance = oldBalance.Balance + insertedTransaction.Sum })));

This code will be translated into sql and applied to migrations will be looks like

public partial class AddTriggers : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.Sql("CREATE FUNCTION LC_TRIGGER_AFTER_INSERT_TRANSACTION() RETURNS trigger as $LC_TRIGGER_AFTER_INSERT_TRANSACTION$ BEGIN INSERT INTO user_balances (user_id, balance) VALUES (NEW.user_id, NEW.sum) ON CONFLICT (user_id) DO UPDATE SET balance = user_balances.balance + NEW.sum; RETURN NEW;END;$LC_TRIGGER_AFTER_INSERT_TRANSACTION$ LANGUAGE plpgsql;CREATE TRIGGER LC_TRIGGER_AFTER_INSERT_TRANSACTION AFTER INSERT ON transactions FOR EACH ROW EXECUTE PROCEDURE LC_TRIGGER_AFTER_INSERT_TRANSACTION();");
    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.Sql("DROP TRIGGER LC_TRIGGER_AFTER_INSERT_TRANSACTION ON transactions;DROP FUNCTION LC_TRIGGER_AFTER_INSERT_TRANSACTION();");
    }
}

Maybe it will be helpful for someone.