Rails challenge

A couple of months ago I stumbled on a reddit post talking about a Rails challenge. I accepted the challenge and finished it with no error. In this blog i would try to share what i learned form that experience.

Rubocop

It was my first time using Rubocop and it was life changing. For those who don’t know Rubocop, It is a static code analyser that would use the Ruby community outline and give you the list of offenses you have in your code. An example would be use && instead of and (more information here).

Serializers

I started by parsing my own JSON data structure and then i realized that it is getting too complicated to i used ActiveModel::Serializer. Serializers describe which attributes and relationships should be serialized. Adapters describe how attributes and relationships should be serialized.

One thing i struggled with was raising an expection when unpermitted parameters were used. I wasted tremendous amount of implementing that fuctionality instead of using the config.action_controller.action_on_unpermitted_parameters = :raise

The Dispatcher algorithm

This was supposed to be the most complicated part of the challenge. After refining my algorithm a couple of times i realized that i could pass the test using this basic logic. I would order the capacacity of the responder by increasing order i would just assign available responder until in don’t have anymore or until i responded fully to the emergency need. It would look like this.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

def dispatch
    RESPONDER_TYPE.each do |key,value|
      # find a responder on duty and available that can handle the emergency on his own
      responder = Responder.by_type(value).on_duty.available.where("capacity = ?", self.send(key))
      # see if we ahve an exact match
      if responder.count == 1
        self.responders << responder
      else
        # if there is no exact match add resources until it is enough for the emergency severity
        add_resource(value,self.send(key))
      end
    end
    self.fully_responded = true if self.enough_resources?
  end

  def add_resource(type,severity)
    responders_by_type = Responder.by_type(type).on_duty.available.order(capacity: :desc)
    responder_severity_sum = 0
    responder_list = []
    responders_by_type.each do |responder|
      if (responder_severity_sum < severity)
        responder_severity_sum += responder.capacity
        self.responders << responder
      end
    end
  end

Conclusion

I really enjoyed working on this challenge and here is my solution. My only regret was not doing it before the deadline because they were going through your solution and grade it. I heard they will have other challenges soon, so stay tuned!