Middlewares

[nesaulov]

Consider having a common logic that has to be executed in many services inside an application. Let's say we have an authorization process:

class UserDependentWebAction < Polist::Service
  def call
    fail!(code: :unauthorized) unless user.admin?
    # ...business logic
  end
  
  private

  def user
    User.find(id: params[:user_id])
  end
end

class AnotherUserDependentWebAction < Polist::Service
  def call
    fail!(code: :unauthorized) unless user.admin?
    # ...business logic
  end

  private

  def user
    User.find(id: params[:user_id])
  end
end

Wouldn't it be better to have middlewares?

class UserAuthorizationMiddleware < Polist::Service::Middleware
  def call
    fail!(code: :unauthorized) unless user.admin?
  end

  private

  def user
    User.find(id: service.params[:user_id])
  end
end

class UserDependentWebAction < Polist::Service
  register_middleware UserAuthorizationMiddleware

  def call
    # ...business logic
  end
end

class AnotherUserDependentWebAction < Polist::Service
  register_middleware UserAuthorizationMiddleware

  def call
    # ...business logic
  end
end

@tycooon what do you think?

[nesaulov]

Wow, I did not notice #1. If your opinion on this topic has not changed, I can make it a plugin system instead of what is present in this pull request.

[tycooon]

This way the middlewares are only going to be called if I do Example.run and not if I do Example.call. And the only difference between these 2 methods should be that the latter raises exception in case of failure.

[tycooon]

I think that this feature is useful enough to be in core gem, but I see some problems with the implementation.

[tycooon]

🤔

[JelF]

I think that this feature is useful enough to be in core gem, but I see some problems with the implementation.

Good news that we already have callbacks implementation in https://github.com/umbrellio/verifly (Verifly::DependentCallbacks)

around callback is same thing as middleware

[coveralls]

Pull Request Test Coverage Report for Build 24

• 91 of 91 (100.0%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 22:	0.0%
Covered Lines:	305
Relevant Lines:	305

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 25

• 91 of 91 (100.0%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 22:	0.0%
Covered Lines:	305
Relevant Lines:	305

---

💛 - Coveralls

[nesaulov]

We can either wait for rubocop/rubocop#6711 to be released (and rubocop-config-umbrellio to be updated), or I can disable this cop manually for this gem. @tycooon

[tycooon]

Let’s just disable it for now.