Refactoring arrays and sub-arrays based on variable value

Question

What is a good syntaxic manner to handle the following array structure and create database records in rails, according to an instance variable?

It is quite obvious that such a structure becomes unwieldly very quickly...

if @event.persons_per_unit == "2"
  if @event.number_units == "1"
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][0]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][0]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][0]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][0]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][0]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][0]['persons'][1]['surname'])
  elsif @event.number_units == "2"
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][0]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][0]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][0]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][0]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][0]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][0]['persons'][1]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][1]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][1]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][1]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][1]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][1]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][1]['persons'][1]['surname'])
  elsif @event.number_units == "3"
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][0]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][0]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][0]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][0]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][0]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][0]['persons'][1]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][1]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][1]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][1]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][1]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][1]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][1]['persons'][1]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][2]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][2]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][2]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][2]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][2]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][2]['persons'][1]['surname'])
  elsif @event.number_units == "4"
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][0]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][0]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][0]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][0]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][0]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][0]['persons'][1]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][1]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][1]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][1]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][1]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][1]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][1]['persons'][1]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][2]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][2]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][2]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][2]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][2]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][2]['persons'][1]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][3]['persons'][0]['type'], 
      first_name: @r['items'][0]['units'][3]['persons'][0]['first_name'], 
      surname: @r['items'][0]['units'][3]['persons'][0]['surname'])
    @entiti = Entiti.create(event_id: @event.id,
      type: @r['items'][0]['units'][3]['persons'][1]['type'], 
      first_name: @r['items'][0]['units'][3]['persons'][1]['first_name'], 
      surname: @r['items'][0]['units'][3]['persons'][1]['surname'])
  else

What does @r look like? That wall of code is a little noisy, might be easier to start with the data. Also, where does the data come from and can you change that to be more convenient? — mu is too short
– mu is too short, Commented Aug 9, 2018 at 22:31

Simple Lime · Accepted Answer · 2018-08-09 22:32:25Z

1

It looks like (unless I'm misreading things) you probably just want a couple of loops. Something along the lines of:

@r['items'].each do |item|
  item['units'].each do |unit|
    unit['persons'].each do |person|
      # if `slice` is available, otherwise just create the hash as you've done
      # using `person` instead of the long nested chain
      Entiti.create(person.slice('type', 'first_name', 'surname').
        merge(event_id: @event.id))
    end
  end
end

if you're worried about things like @event.persons_per_unit == 2 and then having 3 person records in a unit hash, you could use take:

unit['persons'].take(@event.persons_per_unit.to_i).each do |person|
  # ...
end

Same for number of units, if there's a maximum number of units allowed (say, you can't have more than 4, but you are worried you might have 5 in @r['items']. If these are concerns for you, I'd recommend tying an Entiti to the Event (via a has_many) and setting up model validations to make sure things are in line. If the Event model has a has_many already, you could also just @event.entitis.create(...) (not sure how that'll pluralize)

Also, you keep reassigning @entiti, and only the last one will stick, you might want an array if you need all instances later, otherwise no need to store it at all.

answered Aug 9, 2018 at 22:32

Simple Lime

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1 Comment

Jerome Over a year ago

slice turned out to be unavailable. Great pointer on controlling the creation limited to instance variable values

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