CODEWITHSUNDEEP
ruby-on-railsactiverecordruby-on-rails-5database-migrationruby-on-rails-6
Rahul
Rahul

Reputation: 452

Rails dynamic migration with second database

I am trying to create a rails application that can create database tables in a non-primary DB, given a json schema. The app is intended to act as an interface to manage a secondary database. The dynamically created tables will never be accessed by the app except probably (very rarely) to alter the tables.

Here is my setup 

config
 |
 |- secondary_db.yml
 |- initializers/secondary_db.rb

So now my secondary DB config is available throughout the app.

I have a model called Topic which accepts an attribute topic_schema of type json. Assume that the schema is shallow with no hierarchy or nesting. 

topic_schema: {
  "type" => "object",
  "required" => ["a", "b"],
  "properties" => {
    "a" => {"type" => "integer"},
    "b" => {"type" => "string"}
  }
}

I have to create a service class called TableCreator that can take this json schema and create a table based on it. So every time I create a new Topic with a valid json topic_schema, the table gets created automatically. Remember my app is never going to read or write from this table, rarely I may have to alter or delete this table. So I do not need to keep track of these tables in my schema.rb file

I can create a service that can convert json schema to table migration. I want to figure out how can I run the migration to my secondary_db without altering the schema file of my application. Thanks a lot for any help :)

Upvotes: 0

Views: 458

Answers (1)

Rahul
Rahul

Reputation: 452

Here is TableCreator class that achieved what I wanted to do. 

    class TableCreator < ActiveRecord::Migration[6.0]

      def create
        with_secondary_db_connection do
          create_table :ts_test_table, id: false do |t|
            t.datetime 'time'
            t.string 'value'
          end
        end
      end

      def with_secondary_db_connection
        primary = ActiveRecord::Base.remove_connection
        ActiveRecord::Base.establish_connection(TIMESCALE_CONFIG)
        yield
      ensure
        ActiveRecord::Base.establish_connection(primary)
      end

    end

Thanks Max for the suggestion

Upvotes: 2

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