https://github.com/arkency/command_bus

Command Pattern - decoupling what is done from who does it in Ruby and Rails
https://github.com/arkency/command_bus

Last synced: 5 days ago
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Command Pattern - decoupling what is done from who does it in Ruby and Rails

• Host: GitHub
• URL: https://github.com/arkency/command_bus
• Owner: arkency
• Created: 2016-02-05T22:25:47.000Z (almost 9 years ago)
• Default Branch: master
• Last Pushed: 2022-12-15T16:18:58.000Z (almost 2 years ago)
• Last Synced: 2024-10-31T13:15:21.667Z (18 days ago)
• Language: Ruby
• Homepage:
• Size: 22.5 KB
• Stars: 56
• Watchers: 4
• Forks: 5
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md

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README

        
# Command Bus

> Command Pattern - decoupling what is done from who does it.

## Installation

Notice this gem is namespaced.

    gem install arkency-command_bus

## Usage

```ruby

require 'arkency/command_bus'

command_bus = Arkency::CommandBus.new

register    = command_bus.method(:register)

{ FooCommand => FooService.new(event_store: event_store).method(:foo),

  BarCommand => BarService.new,

}.map(&register)

command_bus.(FooCommand.new)

```

### New instance of a service for every command

If need a new instance of a service every time it is called with a command or you want to lazily load the responsible services, you can just use `Proc` during registration.

```ruby

command_bus = Arkency::CommandBus.new

command_bus.register(FooCommand, -> (foo_cmd) { FooService.new(event_store: event_store).foo(foo_cmd) })

command_bus.register(BarCommand, -> (bar_cmd) { BarService.new.call(bar_cmd) })

```

### Working with Rails development mode

In Rails `development` mode when you change a registered class, it is reloaded, and a new class with same name is constructed. 

```ruby

a = User

a.object_id

# => 40737760 

reload!

# Reloading...

 

b = User

b.object_id

# => 48425300

h = {a => 1, b => 2}

h[User]

# => 2 

a == b

# => false 

```

so your `Hash` with mapping from command class to service may not find the new version of reloaded class.

To workaround this problem you can use [`to_prepare`](http://api.rubyonrails.org/classes/Rails/Railtie/Configuration.html#method-i-to_prepare) callback which is executed before every code reload in development, and once in production.

```ruby

config.to_prepare do

  config.command_bus = Arkency::CommandBus.new

  register = command_bus.method(:register)

  { FooCommand => FooService.new(event_store: event_store).method(:foo),

    BarCommand => BarService.new,

  }.map(&register)

end

```

and call it with

```ruby

Rails.configuration.command_bus.call(FooCommand.new)

```

## Convenience alias

```ruby

require 'arkency/command_bus/alias'

```

From now on you can use top-level `CommandBus` instead of `Arkency::CommandBus`.

## About



Command Bus is funded and maintained by Arkency. Check out our other [open-source projects](https://github.com/arkency).

You can also [hire us](http://arkency.com) or [read our blog](http://blog.arkency.com).

## Learn more about DDD & Event Sourcing

Check our **Rails + Domain Driven Design Workshop** [more details](http://blog.arkency.com/ddd-training/).

Why You should attend? Robert has explained this in [this blogpost](http://blog.arkency.com/2016/12/why-would-you-even-want-to-listen-about-ddd/).

Next edition will be held in **September 2017** (Thursday & Friday) in Berlin, Germany.

Workshop will be held in English.