Keep track of all the monies!
DoubleEntry is an accounting system based on the principles of a Double-entry Bookkeeping system. While this gem acts like a double-entry bookkeeping system, as it creates two entries in the database for each transfer, it does not enforce accounting rules.
DoubleEntry uses the Money gem to encapsulate operations on currency values.
DoubleEntry is tested against:
Ruby
- 2.3.x
- 2.4.x
- 2.5.x
- 2.6.x
- 2.7.x
Rails
- 4.2.x
- 5.0.x
- 5.1.x
- 5.2.x
- 6.0.x
- 6.1.x
Databases
- MySQL
- PostgreSQL
- SQLite
In your application's Gemfile
, add:
gem 'double_entry'
Download and install the gem with Bundler:
bundle
Generate Rails schema migrations for the required tables:
The default behavior is to store metadata in a json(b) column rather than a separate
double_entry_line_metadata
table. If you would like the old (1.x) behavior, you can add--no-json-metadata
.
rails generate double_entry:install
Update the local database:
rake db:migrate
The entire API for recording financial transactions is available through a few methods in the DoubleEntry module. For full details on what the API provides, please view the documentation on these methods.
A configuration file should be used to define a set of accounts, and potential transfers between those accounts. See the Configuration section for more details.
Money is kept in Accounts.
Each Account has a scope, which is used to subdivide the account into smaller accounts. For example, an account can be scoped by user to ensure that each user has their own individual account.
Scoping accounts is recommended. Unscoped accounts may perform more slowly than scoped accounts due to lock contention.
To get a particular account:
account = DoubleEntry.account(:spending, scope: user)
(This actually returns an Account::Instance object.)
See DoubleEntry::Account for more info.
Calling:
account.balance
will return the current balance for an account as a Money object.
To transfer money between accounts:
DoubleEntry.transfer(
Money.new(20_00),
from: one_account,
to: another_account,
code: :a_business_code_for_this_type_of_transfer,
)
The possible transfers, and their codes, should be defined in the configuration.
See DoubleEntry::Transfer for more info.
You may associate arbitrary metadata with transfers, for example:
DoubleEntry.transfer(
Money.new(20_00),
from: one_account,
to: another_account,
code: :a_business_code_for_this_type_of_transfer,
metadata: {key1: ['value 1', 'value 2'], key2: 'value 3'},
)
If you're doing more than one transfer in a single financial transaction, or you're doing other database operations along with the transfer, you'll need to manually lock the accounts you're using:
DoubleEntry.lock_accounts(account_a, account_b) do
# Perhaps transfer some money
DoubleEntry.transfer(Money.new(20_00), from: account_a, to: account_b, code: :purchase)
# Perform other tasks that should be commited atomically with the transfer of funds...
end
The lock_accounts call generates a database transaction, which must be the outermost transaction.
See DoubleEntry::Locking for more info.
Although it's unlikely, DoubleEntry has tools for checking accounts to make sure they tie out, and optionally fixing them if there is a discrepancy. It's recommended to run this in a scheduled job, somewhere on the order of hourly to daily, depending on transaction volume. Keep in mind that this process locks accounts as it inspects their balances, so it will have an prevent new transactions from being written for a short time.
Here are examples that could go in your scheduled job, depending on your needs:
# Check all accounts & write the results to the double_entry_line_checks table
DoubleEntry::Validation::LineCheck.perform!
# Check & fix accounts (results will also be written to the table)
DoubleEntry::Validation::LineCheck.perform!(fixer: DoubleEntry::Validation::AccountFixer.new)
See DoubleEntry::Validation for more info.
All transfers and balances are stored in the lines table. As this is a double-entry accounting system, each transfer generates two lines table entries: one for the source account, and one for the destination.
Lines table entries also store the running balance for the account. To retrieve the current balance for an account, we find the most recent lines table entry for it.
See DoubleEntry::Line for more info.
AccountBalance records cache the current balance for each Account, and are used to perform database level locking.
Transfer metadata is stored in a json(b) column on both the source and destination lines of the transfer.
A configuration file should be used to define a set of accounts, optional scopes on the accounts, and permitted transfers between those accounts.
The configuration file should be kept in your application's load path. For example, config/initializers/double_entry.rb. By default, this file will be created when you run the installer, but you will need to fill out your accounts.
For example, the following specifies two accounts, savings and checking. Each account is scoped by User (where User is an object with an ID), meaning each user can have their own account of each type.
This configuration also specifies that money can be transferred between the two accounts.
require 'double_entry'
DoubleEntry.configure do |config|
# Use json(b) column in double_entry_lines table to store metadata instead of separate metadata table
config.json_metadata = true
config.define_accounts do |accounts|
user_scope = ->(user) do
raise 'not a User' unless user.class.name == 'User'
user.id
end
accounts.define(identifier: :savings, scope_identifier: user_scope, positive_only: true)
accounts.define(identifier: :checking, scope_identifier: user_scope)
end
config.define_transfers do |transfers|
transfers.define(from: :checking, to: :savings, code: :deposit)
transfers.define(from: :savings, to: :checking, code: :withdraw)
end
end
By default an account's currency is the same as Money.default_currency from the money gem.
You can also specify a currency on a per account basis. Transfers between accounts of different currencies are not allowed.
DoubleEntry.configure do |config|
config.define_accounts do |accounts|
accounts.define(identifier: :savings, scope_identifier: user_scope, currency: 'AUD')
end
end
Run a concurrency test on the code.
This spawns a bunch of processes, and does random transactions between a set of accounts, then validates that all the numbers add up at the end.
You can also tell it to flush out the account balances table at regular intervals, to validate that new account balances records get created with the correct balances from the lines table.
./script/jack_hammer -t 20
Cleaning out the database...
Setting up 5 accounts...
Spawning 20 processes...
Flushing balances
Process 1 running 1 transfers...
Process 0 running 1 transfers...
Process 3 running 1 transfers...
Process 2 running 1 transfers...
Process 4 running 1 transfers...
Process 5 running 1 transfers...
Process 6 running 1 transfers...
Process 7 running 1 transfers...
Process 8 running 1 transfers...
Process 9 running 1 transfers...
Process 10 running 1 transfers...
Process 11 running 1 transfers...
Process 12 running 1 transfers...
Process 13 running 1 transfers...
Process 14 running 1 transfers...
Process 16 running 1 transfers...
Process 15 running 1 transfers...
Process 17 running 1 transfers...
Process 19 running 1 transfers...
Process 18 running 1 transfers...
Reconciling...
All the Line records were written, FTW!
All accounts reconciled, FTW!
Done successfully :)
See the Github project issues.
We're using Docker to provide a convenient and consistent environment for executing tests during development. This allows engineers to quickly set up a productive development environment.
Note: Most development files are mounted in the Docker container. This enables engineers to edit files in their favourite editor (on the host OS) and have the changes immediately available in the Docker container to be exercised.
One exception to this is the RSpec configuration. Changes to these files will require a rebuild of the Docker image (step 2).
Prerequisites:
- Docker
- Docker Compose
- Git
-
Clone this repo.
git clone git@github.com:envato/double_entry.git && cd double_entry
-
Build the Docker image we'll use to run tests
docker-compose build --pull double_entry
-
Startup a container and attach a terminal. This will also start up a MySQL and Postgres database.
docker-compose run --rm double_entry ash
-
Run the tests
DB=mysql bundle exec rspec DB=postgres bundle exec rspec DB=sqlite bundle exec rspec
-
When finished, exit the container terminal and shut down the databases.
exit docker-compose down
Many thanks to those who have contributed to both this gem, and the library upon which it was based, over the years:
- Anthony Sellitti - @asellitt
- Clinton Forbes - @clinton
- Eaden McKee - @eadz
- Giancarlo Salamanca - @salamagd
- Jiexin Huang - @jiexinhuang
- Keith Pitt - @keithpitt
- Kelsey Hannan - @KelseyDH
- Mark Turnley - @rabidcarrot
- Martin Jagusch - @MJIO
- Martin Spickermann - @spickermann
- Mary-Anne Cosgrove - @macosgrove
- Orien Madgwick - @orien
- Pete Yandall - @notahat
- Rizal Muthi - @rizalmuthi
- Ryan Allen - @ryan-allen
- Samuel Cochran - @sj26
- Stefan Wrobel - @swrobel
- Stephanie Staub - @stephnacios
- Trung Lê - @joneslee85
- Vahid Ta'eed - @vahid