This past week or so I’ve had another run in with using Rails to access data across Postgres schemas. I thought I would share some of my experiences I’ve had with the two.

I’m going to assume you’re comfortable with Rails (ActiveRecord with models) and Postgres (what is a schema and why you’d want to use one).

The wild wild west of data

I had a public schema for most of my data (people, preferences, etc) and another schema bikeshop that has several entries from an external data feed, that may or may not change format along the way.

To ActiveRecord – or not to be

First I tried making some simple ActiveRecord classes, all while admitting I’m really not that fond of ActiveRecord.

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class BikeStore < ActiveRecord::Base
  set_table_name 'bikes.store'
end

Easy right? It happens to work too, sweet.

Wait, I thought you wrote tests too?

Woops, let’s get that set up too. First I’ll start by setting up my fixtures (heres a few reasons I still use minitest & fixtures). I started by naming my file bikeshop.yml and it looks like this:

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first:
  id: 1
  name: 'Jims Bike shop'

And a quick test:

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require 'test_helper'
class BikeStoreTest < ActiveSupport::TestCase
  before do
      @bike_store = bikesstore(:first)
  end

  test 'should get bike store name' do
      refute_nil @bike_store
  end
end

Right away you’ll get one of these errors:

• There is no table named bikestore
• There is no function named bikesstore

How do you even use or access the fixture data then?

Fixture naming with schemas

The trick is this: naming the fixture yaml file schema.table.yml – that properly sets up the fixture to let us get some test data. I called my file bikes.store.yml and that fixed things up.

Accessing the fixture data in a test

Still not sure on this one folks. Please someone comment and help the world out!

Hope this helps