Do I Edit the Migration Too to Show the Belongs To

Question

Do I edit the corresponding migration also to show the belongs_to (and the has_many)? I have a many to many relationship where I am using the "has_many :through" association. When I place in the individual classes the 'has_many :through' and the 'belongs_to' associations, do I also edit the corresponding migrations to reflect those changes?
I would like those changes to be reflected in the database also, but I don't know whether there was a way to run one of the migration generator commands that would have included these associations.
Also, I have already run the migration so is there a way to create a new migration that would simply add these associations? I would prefer not to edit existing migrations.

Answer 1

1. No, there is no need to change the existing migrations. The relationship declarations (has_many and so on) have not direct effect on the database contents, they just tell Rails what to expect in the database.

2. Whenever you make a change to the database use a new migration. You will just get yourself (and likely the database) very confused if you try to add to an existing migration.

3. Work right through a good tutorial such as railstutorial.org (which is free to use online) before starting you own experiments. That will show you the basics of Rails.