Multiple Databases With Rails Not Working For Remote Database

问题

I have a remote read-only postgres database that is maintained from a docker instance of cardano-db-sync.

I managed to connect the development database to it, it was working fine. But since it is read-only I wanted to add another database for User and other modifiable tables.

this is the set up I prepared:

# config/database.yml
default: &default
  adapter: postgresql
  encoding: unicode
  pool: 5

development:
  <<: *default
  primary:
    database: 'db_sync'
  cexplorer:
    database: 'cexplorer'
    username: <%= ENV['HOST_PG_DATABASE_USERNAME'] %>
    password: <%= ENV['HOST_PG_DATABASE_PASSWORD'] %>
    host: <%= ENV['HOST_PG_DATABASE_IP'] %>
    port: <%= ENV['HOST_PG_PORT'] %>

then the abstracted classes as in the doc instructions

# app/models/application_record.rb
class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true

  connects_to database: { reading: :primary, write: :primary}
end

# app/models/cexplorer_record.rb
class CexplorerRecord < ApplicationRecord
  self.abstract_class = true

  connects_to database: { reading: :cexplorer }
end

then some tables to test:

# app/models/pool_hash.rb
class PoolHash < CexplorerRecord
    self.table_name = 'pool_hash'
end

# app/models/pool.rb
class Pool < ApplicationRecord
end

The primary database seems to work fine with rails c but once using PoolHash I get this error:

$ rails c
Running via Spring preloader in process 79267
Loading development environment (Rails 6.0.3.4)
2.6.1 :001 > PoolHash.count
Traceback (most recent call last):
        4: from (irb):1
        3: from app/models/pool_hash.rb:1:in `<main>'
        2: from app/models/cexplorer_record.rb:1:in `<main>'
        1: from app/models/cexplorer_record.rb:4:in `<class:CexplorerRecord>'
ActiveRecord::AdapterNotSpecified (The `cexplorer` database is not configured for the `development` environment.)

Available databases configurations are:

default
development
2.6.1 :002 > Pool.count
   (0.5ms)  SELECT COUNT(*) FROM "pools"
 => 0 
2.6.1 :003 >

I don't get why it says cexplorer is not configured for development when is instead right there in database.yml in the same config that worked when it was without the :primary

UPDATE

it seems that by moving the <<: *default things improved:

development:
  primary:
    <<: *default
    database: 'swan_db_sync'
  cexplorer:
    <<: *default
    database: 'cexplorer'
    username: <%= ENV['HOST_PG_DATABASE_USERNAME'] %>
    password: <%= ENV['HOST_PG_DATABASE_PASSWORD'] %>
    host: <%= ENV['HOST_PG_DATABASE_IP'] %>
    port: <%= ENV['HOST_PG_PORT'] %>

but I now get a different problem:

rails c        
Running via Spring preloader in process 79798
Loading development environment (Rails 6.0.3.4)
2.6.1 :001 > Pool.count
   (4.2ms)  SELECT COUNT(*) FROM "pools"
 => 0 
2.6.1 :002 > PoolHash.count
Traceback (most recent call last):
        1: from (irb):2
ActiveRecord::ConnectionNotEstablished (No connection pool with 'CexplorerRecord' found.)

UPDATE 2

I have now tried a setup as in this article managing multiple databases in a single rails application link from 2017.

It works fine. It also makes more sense for my goal than what is in the rails documentation. I hope being an old article won't give me surprises down the line.

来源：https://stackoverflow.com/questions/65541744/multiple-databases-with-rails-not-working-for-remote-database

标签

ruby-on-rails

postgresql

multiple-databases