How do I get ActiveRecord to show the next id (last + 1) in Ruby on Rails?

Question

Is there a compact way with ActiveRecord to query for what id it\'s going to use next if an object was going to be persisted to the database? In SQL, a query like this would

Answer 1

If you want to be sure no one else can take the 'new' index, you should lock the table. By using something like:

ActiveRecord::Base.connection.execute("LOCK TABLES table_name WRITE")

and

ActiveRecord::Base.connection.execute("UNLOCK TABLES")

But this is specific for each database engine.

The only correct answer for a sequential id column is:

YourModel.maximum(:id)+1

If you sort your model in a default scope, last and first will depend on that order.