Question

Suppose I have two models A and B

Now I want to copy some information from an instance of A to an instance of B by clicking a button

Is there a way of doing it?

Answer 1

This process is called cloning an object and the complexity of it depends on what kind of information you would like to clone.

If you simply want to clone an object’s fields, you would do something like this:

old_object = A.find(old_object_id)
new_object = B.new

new_object.field_one = old_object.field_one
new_object.field_two = old_object.field_two
new_object.save!

If, however, you want to also clone the old object’s associations, you will need to do that by hand.

Say for the sake of argument that A had a has_many association of B objects called bees, and B has_many C objects called sees, this could get a little complex:

old_object.bees.each do |bee|
   new_bee = bee.clone
   new_bee.sees.each do |see|
      new_see = see.clone
      new_see.save!
   end
   new_object.bees.push(new_bee)
end
new_object.save!