https://github.com/exponentially/helios_aggregate

https://github.com/exponentially/helios_aggregate

Last synced: 3 months ago
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• Host: GitHub
• URL: https://github.com/exponentially/helios_aggregate
• Owner: exponentially
• License: apache-2.0
• Created: 2018-06-03T13:51:12.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2018-08-31T07:45:58.000Z (about 6 years ago)
• Last Synced: 2024-05-12T15:46:44.125Z (6 months ago)
• Language: Elixir
• Size: 16.6 KB
• Stars: 3
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-elixir-cqrs - Helios.Aggregate - Elixir library defining Aggregate behaviour and providing extendable facility for aggregate command pipeline. (Libraries)

README

        
# Helios.Aggregate

Elixir library defining Aggregate behaviour and providing extendable facility for aggregate command pipeline.

Please note this package is not full CQRS framework. We strongly disagree that CQRS can be boxed into framewrok, it is rather set of

techniques you CAN apply to your service architecture.

## Installation

[Available in Hex](https://hex.pm/packages/helios_aggregate), the package can be installed

by adding `helios_aggregate` to your list of dependencies in `mix.exs`:

```elixir

def deps do

  [

    {:helios_aggregate, "~> 0.1"}

  ]

end

```

## Aggregate example

```elixir

defmodule Customer do

  use Helios.Aggregate

  # Aggregate state

  defstruct [:first_name, :last_name, :email]

  # Events emitted by aggregate

  defmodule CustomerCreated, do: defstruct [:id, :first_name, :last_name]

  defmodule CustomerContactCreated, do: defstruct [:email]

  def create(ctx, %{first_name: first_name, last_name: last_name, email: email}) do

    

    ctx

    |> emit_event(%CustomerCreated{first_name: first_name, last_name: last_name})

    |> emit_event(%CustomerContactCreated{email: email})

  end

  def apply_event(customer, %CustomerCreated{}=event) do

    %{customer|

      first_name: event.first_name,

      last_name: event.last_name

    }

  end

  def apply_event(customer, %CustomerContactCreated{email: email}) do

    %{customer| email: email}

  end

end

```

```elixir

  ctx = %Helios.Aggregate.Pipeline.Context{

    aggregate: %Helix.Aggregate{state: },

    aggregate_module: CustomerAggregate,

    correlation_id: "1234567890",

    command: :create_user,

    peer: self(),

    params: %{first_name: "Jhon", last_name: "Doe", email: "[email protected]"}

  }

  Cusomer.call(ctx, :create)

    

```

## Logger configuration

We build logger which should log each command sent to aggregate. Since commands can cary some confidential information, or you have to be PCI DSS compliant, 

we expsed configuration like below where you could configure which filed values in command should be retracted.

Below is example where list of field names are given. Please note, the logger plug will not try to conver string to atom or other way round, if you have both case

please state them in list as both, string and atom.

```elixir

use Mix.Config

# filter only specified

config :helios_aggregate, 

  :filter_parameters, [:password, "password", :credit_card_number]

# filter all but keep original values

config :helios_aggregate, 

  :filter_parameters, {:keep, [:email, "email", :full_name]}

# retract only specified field values

config :helios_aggregate, 

  :filter_parameters, [:password, "password", :credit_card_number]

```

Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)

and published on [HexDocs](https://hexdocs.pm). Once published, the docs can

be found at [https://hexdocs.pm/helios_aggregate](https://hexdocs.pm/helios_aggregate).