In data_mapper, what is the best way to update a record or create a new one if it doesn't exist?

Question

I'm using data_mapper in my own sinatra project.

So, what is the best way to update a record or create a new one with initial value if it doesn't exist?

E.g., I have a model like

class Model
  include DataMapper::Resource
  property :id, Serial
  property :count, Integer
end

Is there a way that can check the existence of the model, then increase the count if exist or create a new model and set the count to 0

THX

Answer 1

This should work:

model = Model.first
if model
  model.update(count: model.count + 1)
else
  model = Model.create(count: 0)
end