This patch introduces a new `ServiceJob` class allowing the use of
`with_service` in jobs.
This way, it’s easier to use the chat service objects in jobs and
provides the same level of functionality than the one we have in
controllers.
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>'
```
Instead of passing `user` to `guardian.can_chat?`, we
can just use the inner `@user` that is part of the guardian
instance already to determine whether that user can chat,
since this is how it works for all other usages of guardian
even within chat.
Loïc Guitaut
Martin Brennan
Roman Rizzi