Best way to find_or_create_by_id but update the attributes if the record is found

Question

I\'m looking for a clean way to create a record with a set of attributes if the record does not exist and - if the record do exist - to update its attributes. I love the syn

Answer 1

I liked fl00r's answer. But why do we have to save the object every time? We can check if its already there in records or else save it

def self.find_or_create_by_id(id, &block)
    obj = self.find_by_id(id) 
    unless obj
      obj = self.create(id: id)
    end
    obj
end

Answer 2

Try this:

c = Category.find_or_initialize_by_id(category.id)
c.name = category.name
c.save!

This way you only save the instance once, instead of twice, if you called find_or_create_by_id (assuming it's a new record).

Answer 3

I did this yesterday, wishing there was a way to do it in a one-liner.

Ended up going with (using your code):

c = Category.find_or_initialize_by_id(category.id)
c.name = category.name
c.save

Perhaps there is a nicer way, but this is what I used.

[Edit: use initialize instead of create to avoid hitting the DB twice)

Answer 4

I have coded this finders that can be used for different scenarios.

The most important thing is, that it removes the parameter :id on create and update.

Creating a model with :id can cause problems with MySql or PostgreSQL because Rails uses the auto sequence number of the database. If you create new model instances with an :id you can get a UniqueViolation: ERROR: duplicate key value violates unique constraint.

# config/initializers/model_finders.rb
class ActiveRecord::Base

  def self.find_by_or_create(attributes, &block)
    self.find_by(attributes) || self.create(attributes.except(:id), &block)
  end


  def self.find_by_or_create!(attributes, &block)
    self.find_by(attributes) || self.create!(attributes.except(:id), &block)
  end


  def self.find_or_create_update_by(attributes, &block)
    self.find_by(attributes).try(:update, attributes.except(:id), &block) || self.create(attributes.except(:id), &block)
  end


  def self.find_or_create_update_by!(attributes, &block)
    self.find_by(attributes).try(:update!, attributes.except(:id), &block) || self.create!(attributes.except(:id), &block)
  end


  def self.find_by_or_initialize(attributes, &block)
    self.find_by(attributes) || new(attributes.except(:id), &block)
  end

end

Answer 5

I have been using this patten for seeds:

Category.find_or_initialize_by(id: category.id).update |c|
  c.name = category.name
end

It works the same as Dale Wijnand's and Teoulas answers (only saves the instance once) but uses a block like in your question.

Answer 6

You can write your own method:

class ActiveRecord::Base
  def self.find_by_id_or_create(id, &block)
    obj = self.find_by_id( id ) || self.new
    yield obj
    obj.save
  end
end

usage

 Category.find_by_id_or_create(10) do |c|
   c.name = "My new name"
 end

Of course, in this way you should extend method missing method and implement this method in the same way as others find_by_something methods. But for being short this will be enough.