rdt (Ruby Data Tool)

SQL-based data modeling for Rails applications.

Usage

Use Rdt.run to build your models:

Rdt.run

Resources from the Extractor gem

Basic steps to clean, deduplicate and model Extractor results:

1. Clean responses and unroll arrays

Create a .sql file named example_cleaned containg exactly the following columns

1. unique_by
2. created_at
3. request_id
4. body

-- example_cleaned.sql
SELECT
  response_options -> 'response_body' ->> 'id' AS unique_by,
  created_at,
  id AS request_id,
  response_options -> 'response_body' AS body
FROM <%= source('requests') %>
WHERE extractor_class =  'ExampleTap'

Responses with multiple items

Use jsonb_path_query to split arrays of items to individual records

-- example_cleaned.sql
SELECT
  jsonb_path_query(response_options, '$.response_body[*].body.id') #>> '{}' AS unique_by,
  created_at,
  id AS request_id,
  jsonb_path_query(response_options, '$.response_body[*].body') body
FROM <%= source('requests') %>
WHERE extractor_class = 'MultipleItemsTap'

2. Deduplicate

-- example_deduplicated.sql
SELECT
  DISTINCT ON(unique_by)
  *
FROM <%= ref('example_cleaned') %>
ORDER BY unique_by, created_at DESC

3. Model

-- example_model.sql
SELECT
  body ->> 'id' AS id,
  body ->> 'userId' AS user_id,
  body ->> 'title' AS title,
  body ->> 'body' AS body
FROM <%= ref('example_deduplicated') %>

Using SQL models as Active Record models

SQL models are currently materialized as either views or materialized views, those can be used as tables backing Active Record models, but are inherently read-only. To use a SQL model as an Active Record model, create a ruby file in app/models defining a class that inherits from ApplicationRecord. Remember that for Zeitwert to autoload your file it should follow the naming conventions (class name should be the CamelCase version of the snake_case file name: inventory_transfer.rb defines class InventoryTranfer.

# app/models/example_name.rb
class ExampleName < ApplicationRecord
  self.table_name = "rdt.example_model"
end

This, after re-entering the rails console, enables queries like:

3.1.0 :001 > ExampleName.first
 =>
#<ExampleName:0x00000001126864e8
 id: 1,
 user_id: 1,
 title: "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
 body:
  "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto">