discourse/documentation/chat/backend/top-level-namespace.html
Martin Brennan 60ad836313
DEV: Chat service object initial implementation (#19814)
This is a combined work of Martin Brennan, Loïc Guitaut, and Joffrey Jaffeux.

---

This commit implements a base service object when working in chat. The documentation is available at https://discourse.github.io/discourse/chat/backend/Chat/Service.html

Generating documentation has been made as part of this commit with a bigger goal in mind of generally making it easier to dive into the chat project.

Working with services generally involves 3 parts:

- The service object itself, which is a series of steps where few of them are specialized (model, transaction, policy)

```ruby
class UpdateAge
  include Chat::Service::Base

  model :user, :fetch_user
  policy :can_see_user
  contract
  step :update_age

  class Contract
    attribute :age, :integer
  end

  def fetch_user(user_id:, **)
    User.find_by(id: user_id)
  end

  def can_see_user(guardian:, **)
    guardian.can_see_user(user)
  end

  def update_age(age:, **)
    user.update!(age: age)
  end
end
```

- The `with_service` controller helper, handling success and failure of the service within a service and making easy to return proper response to it from the controller

```ruby
def update
  with_service(UpdateAge) do
    on_success { render_serialized(result.user, BasicUserSerializer, root: "user") }
  end
end
```

- Rspec matchers and steps inspector, improving the dev experience while creating specs for a service

```ruby
RSpec.describe(UpdateAge) do
  subject(:result) do
    described_class.call(guardian: guardian, user_id: user.id, age: age)
  end

  fab!(:user) { Fabricate(:user) }
  fab!(:current_user) { Fabricate(:admin) }

  let(:guardian) { Guardian.new(current_user) }
  let(:age) { 1 }

   it { expect(user.reload.age).to eq(age) }
end
```

Note in case of unexpected failure in your spec, the output will give all the relevant information:

```
  1) UpdateAge when no channel_id is given is expected to fail to find a model named 'user'
     Failure/Error: it { is_expected.to fail_to_find_a_model(:user) }

       Expected model 'foo' (key: 'result.model.user') was not found in the result object.

       [1/4] [model] 'user' 
       [2/4] [policy] 'can_see_user'
       [3/4] [contract] 'default'
       [4/4] [step] 'update_age'

       /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/update_age.rb:32:in `fetch_user': missing keyword: :user_id (ArgumentError)
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:202:in `instance_exec'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:202:in `call'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:219:in `call'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:417:in `block in run!'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:417:in `each'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:417:in `run!'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:411:in `run'
       	from <internal:kernel>:90:in `tap'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:302:in `call'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/spec/services/update_age_spec.rb:15:in `block (3 levels) in <main>'
```
2023-02-13 13:09:57 +01:00

111 lines
1.9 KiB
HTML

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>
Top Level Namespace
&mdash; Documentation by YARD 0.9.28
</title>
<link rel="stylesheet" href="css/style.css" type="text/css" />
<link rel="stylesheet" href="css/common.css" type="text/css" />
<script type="text/javascript">
pathId = "";
relpath = '';
</script>
<script type="text/javascript" charset="utf-8" src="js/jquery.js"></script>
<script type="text/javascript" charset="utf-8" src="js/app.js"></script>
</head>
<body>
<div class="nav_wrap">
<iframe id="nav" src="class_list.html?1"></iframe>
<div id="resizer"></div>
</div>
<div id="main" tabindex="-1">
<div id="header">
<div id="menu">
<a href="_index.html">Index</a> &raquo;
<span class="title">Top Level Namespace</span>
</div>
<div id="search">
<a class="full_list_link" id="class_list_link"
href="class_list.html">
<svg width="24" height="24">
<rect x="0" y="4" width="24" height="4" rx="1" ry="1"></rect>
<rect x="0" y="12" width="24" height="4" rx="1" ry="1"></rect>
<rect x="0" y="20" width="24" height="4" rx="1" ry="1"></rect>
</svg>
</a>
</div>
<div class="clear"></div>
</div>
<div id="content"><h1>Top Level Namespace
</h1>
<div class="box_info">
</div>
<h2>Defined Under Namespace</h2>
<p class="children">
<strong class="modules">Modules:</strong> <span class='object_link'><a href="Chat.html" title="Chat (module)">Chat</a></span>
</p>
</div>
<div id="footer">
Generated by
<a href="https://yardoc.org" title="Yay! A Ruby Documentation Tool" target="_parent">yard</a>
0.9.28.
</div>
</div>
</body>
</html>