Active Record Relation - new vs build
These are the same as of this writing. build is an alias of new. (See: rails/activerecord/lib/active_record/relation.rb)
- Used for association.
- Returns an object in memory but doesn’t modify the database.
- Automatically fill in a
user_idattribute equal to its associated user’s id.
# GOOD: Idiomatically correct
@user = users(:michael)
@micropost = @user.microposts.build(content: "Lorem ipsum")
# BAD: Idiomatically incorrect (functionally the same as above)
@user = users(:michael)
@micropost = Micropost.new(content: "Lorem ipsum", user_id: @user.id)