How to make my seeds file Idempotent?

Question

In my deployment process I am running my seeds file. I want this to be Idempotent so I can run it multiple times without any issue.

Currently I get PG primary key errors if I run it multiple times.

My seeds pattern looks like this:

user = User.create(.....)
user.save!

foo = Foo.create(....)
foo.save!

How can I make this Idempotent?

Is this the best way?

if( user.exists?(some_column: some_value) )
else
  # do insert here 
end 

Answer 1

I believe you can make use of first_or_create

User.where(email: "[email protected]").first_or_create do |user|
  user.name = "John"
end

This will only create User with email = "[email protected]" if it doesn't exist or it will return you the instance of existing User.

This way you can avoid the Unique Key Violation

Answer 2

You can try :

unless user.find_by(some_column: some_value)
    user.save!
end