IvanRublev / bank-commanded-domo

Bank

This repo is a fork of https://github.com/vasspilka/bank example seasoned with Domo library in Command and Event modules.

That extended example is for "Eventsourcing and CQRS in Elixir" talk by Vasilis Spilka at ElixirConf EU 2021 https://youtu.be/GEFbhMZlxzE

Functions of Account context, process manager, and projector constructs commands and events with conformance to their types by calling to new/1 or new!.

That includes the validation of the account_number() value format via precondition defined in Bank module.

That brings the following errors to the User Interface automatically:

iex(1)> alias Bank.Core.Accounts
iex(1)> Accounts.deposit_money(nil, 10)        
{:error,
 [
   account_id: "Invalid value nil for field :account_id of %Bank.Core.Commands.DepositMoney{}. Expected the value matching the <<_::_*8>> type."
 ]}

iex(2)> Accounts.deposit_money("100102", 500)        
{:error, 
  [
    account_id: "Account number should be of xxx-xxx, x = 0..9 format."
  ]}

iex(3)> Accounts.deposit_money("100-102", -12)
{:error,
 [
   amount: "Invalid value -12 for field :amount of %Bank.Core.Commands.DepositMoney{}. Expected the value matching the non_neg_integer() type."
 ]}

iex(4)> Accounts.deposit_money("100-102", 120)
{:ok, %Commanded.Commands.ExecutionResult{}} 

The casting of Event from Command with type mismatch produces runtime error.

The config :domo, :skip_defaults, true in config.exs is to disable verification of Commands and Events default values during compile time because fields are overwritten in Accounts context, Manager, and Projector anyway.

To start your Phoenix server:

• Install dependencies with mix deps.get
• Create and init event store database with mix do event_store.create, event_store.init
• Create and migrate your database with mix ecto.setup
• Start iex with iex -S mix

Now you can visit localhost:4000 from your browser.

Ready to run in production? Please check our deployment guides.

Learn more

• Official website: https://www.phoenixframework.org/
• Guides: https://hexdocs.pm/phoenix/overview.html
• Docs: https://hexdocs.pm/phoenix
• Forum: https://elixirforum.com/c/phoenix-forum
• Source: https://github.com/phoenixframework/phoenix