Standalone Ruby -- How to Load Different Environments from Database.Yml

Standalone ruby -- How to load different environments from database.yml

I would set up the connection once at the start of your background process. Once you've established the connection once, all of the models will work correctly anyway.

Your connection establishment code would look something like this:

@environment = ENV['RACK_ENV'] || 'development'
@dbconfig = YAML.load(File.read('config/database.yml'))
ActiveRecord::Base.establish_connection @dbconfig[@environment]

How to use ActiveRecord for Multiple Environment outside Rails?

What rails does may look like magic, but it's actually very simple (well, this case, at least). Here's the outline:

At startup, app loads all available database configurations. By convention, they are stored in YAML format in config/database.yml.

Then, current environment is determined. The easiest way to do this is environment variables. For example:

 MY_ENV=production ruby my_script.rb

Then, in the script, you fetch current env, pick corresponding connection configuration and use it to connect.

connection_configs = YAML.load(File.read('config/database.yml'))
current_env = ENV['MY_ENV'] || 'development' # if no value, assume development mode
ActiveRecord::Base.establish_connection(connection_configs[current_env])

RoR environment in Ruby standalone script

The easiest way is to change the shebang of your script from :

#!/usr/bin/ruby

to

#!/path/to/your/rails/script/runner

Et voilà, your script will be run with the full rails environment loaded. You can also run your script as ./my_script -e production to have it run with the production database.

Rails database.yml configuration with different sockets on dev, test and production

You can specify the Rails environment when you run the Rake task.

rake db:migrate RAILS_ENV=production

How can I load ActiveRecord database tasks on a Ruby project outside Rails?

You could try the standalone-migrations gem:
https://github.com/thuss/standalone-migrations

passenger start standalone with RAILS_ENV=production

Solved! I passed now this command:

passenger start -a 127.0.0.1 -p 3000 -d --environment production

Trouble connecting to database in standalone ActiveRecord app

I do this also, but I don't use rake, I just use pure ruby. Here are a couple of methods from my project where I use Active record outside of rails.

Basically I connect to the database, check to see if the tables exist, and if not I load the schema file. Once the schema is loaded, I just use normal ActiveRecord methods to populate the database and do queries. I have no need to do migrations so I have not tried that

class MyDb
  attr_reader :file_name
  def initialize(file_name)
    @file_name = file_name
  end

  def connect()
    @connection = ActiveRecord::Base.establish_connection(
      adapter: "sqlite3",
      database: filename,
    )
    create_tables unless tables_exists?
  end

  def tables_exists?
    ActiveRecord::Base.connection.tables.size > 0
  end

  def create_tables()
    puts "database is empty...\ncreating tables"
    path_to_current_file = File.expand_path(File.dirname(__FILE__))
    load("#{path_to_current_file}/ar_support/schema.rb")
  end
end

Then from inside a top level ruby script you can do something like.

my_db = MyDb.new("mydb.sqlite3")
my_db.connect

Here is an example schema.rb file that I also use.

ActiveRecord::Schema.define(version: 20180430230151) do

  create_table "chips", force: :cascade do |t|
    t.string "name"
  end

  create_table "macros", force: :cascade do |t|
    t.string "name"
    t.integer "chip_id"
    t.index ["chip_id"], name: "index_macros_on_chip_id"
  end

  create_table "measurements", force: :cascade do |t|
    t.string "name"
    t.float "value"
    t.string "group_name"
    t.string "plot"
    t.boolean "test_result"
    t.string "test_expression"
    t.integer "run_id"
    t.index ["run_id"], name: "index_measurements_on_run_id"
  end

  create_table "runs", force: :cascade do |t|
    t.string "source_dir"
    t.string "source_file"
    t.integer "macro_id"
    t.string "corner_name"
    t.string "sim_type"
    t.string "netlist_type"
    t.index ["macro_id"], name: "index_runs_on_macro_id"
  end

  create_table "tags", force: :cascade do |t|
    t.string "name"
    t.integer "run_id"
    t.string "value"
    t.index ["run_id"], name: "index_tags_on_run_id"
  end

end

Start using the database. (You also need to define your models)

chip = Chip.find_or_create_by(name: e.chip)
macro = chip.macros.find_or_create_by(name: e.macro)

configuration file for a standalone ruby script

First, you can run an independent script that writes to a YAML configuration file:

require "yaml"
File.write("path_to_yaml_file", [arg1, arg2].to_yaml)

Then, read it within your app:

require "yaml"
arg1, arg2 = YAML.load_file("path_to_yaml")
# use arg1, arg2
...

---

Related Topics