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I have a store which holds objects like [obj1, obj2, obj3] with attributes date, task, staff, etc. The objects contains data like date "18.07.2019", staff 1001, task 1

My initial idea was to group them somehow, but I miserably failed. I'd like build a structure as shown at the bottom of the post, either from the objects itselves or from an contructed array holding only three (or maybe more) attributes.

Challenge:

As I am using an very old ruby 1.6 I can't use all the modern easy methods.

The store consists of objects like [obj1, obj2, obj3] with attributes date, task, staff. 

    all_items = []
    store.each do |obj|
      all_items << [obj.date, obj.task, obj.staff]
    end

My attempt:

I tried a lot like 

    h = {}
    h[date] = []
    h[date] << [obj.date, obj.task, obj.staff]
    h[date].to_h

Current state: 

    h = {}
    all_items = []
    store.each do |obj|
      h[obj.date.to_s] = []
      h[obj.date.to_s] << { obj.date.to_s => [obj.staff, obj.task] }
      all_items << Hash[*h[obj.date.to_s].flatten]
    end
    puts all_items.inspect

looks like this (still nothing I can work with): 

[ 
  {"18.07.2019"=>[1001, 2]}, 
  {"18.07.2019"=>[1001, 2]}, 
  {"18.07.2019"=>[1001, 3]}, 
  {"19.07.2019"=>[1001, 1]}, 
  {"20.07.2019"=>[1002, 3]},
  ...
]

Expected format:

I would love to come out with something like this, so that I know who has which tasks on which date in order to work with the data later in my program.

{
  "18.07.2019" => [
    { staff: 1001, tasks: [1, 2, 3]},
    { staff: 1002, tasks: [1, 2, 4]}
  ],
  "19.07.2019" => [
    { staff: 1001, tasks: [2, 3]},
    { staff: 1002, tasks: [1, 2]}
  ],
  ...
}
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6
  • What's the input data? Commented Aug 7, 2019 at 19:40
  • Updated the beginning of my question, the store consists of objects like [obj1, obj2, obj3] with attributes date, task, staff, etc. Commented Aug 7, 2019 at 19:42
  • 1
    You can add an example of your input data. I'm not gonna tell anybody how your data looks like. Commented Aug 7, 2019 at 19:44
  • I am using an external SDK an get objects back as described. Not sure if the input data is really relevant. I can only access certain methods of the objects as described. Do you expect a class and some methods? Commented Aug 7, 2019 at 19:47
  • No, if your expected output is like in the answer, there should be a "18.07.2019", 1001, [1,2,3], ... in somewhere. Commented Aug 7, 2019 at 19:50

1 Answer 1

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1

Unfortunately, I don't have an actual Ruby 1.6 available since its last update was releases in 2002 and it doesn't compile on any modern system anymore. As such, I wasn't able to test if this code actually works on this Ruby version.

Still, you should be able to get your desired result with something like this:

result = {}
store.each do |obj|
  date = obj.date.to_s
  staff = obj.staff
  task = obj.task

  # An Array of Hashes for each date in the result hash
  result[date] ||= []

  # Find an existing Hash for the current staff id
  staff_obj = result[date].find { |hash| hash[:staff] == staff }

  # If we don't have a Hash for the current staff id yet, create a new one
  # and add it to the result Hash
  unless staff_obj
    staff_obj = { :staff => staff, :tasks => [] }
    result[date] << staff_obj
  end

  # Finally, we add the current task id to the list of tasks for
  # the current date and staff
  staff_obj[:tasks] << task
end

puts result.inspect

Note that this can be rather inefficient to create your desired data structure if there are a lot of different staff ids since we have to find the existing hash for the date and staff in each loop. This could be improved by using a different result structure such as:

{
  "18.07.2019" => {
    1001 => [1, 2, 3],
    1002 => [1, 2, 4]
  },
  "19.07.2019" => {
    1001 => [2, 3],
    1002 => [1, 2]
  },
  ...
}

To create this structure, you could use this simplified approach which should be quite efficient:

result = {}
store.each do |obj|
  date = obj.date.to_s
  staff = obj.staff
  task = obj.task

  result[date] ||= {}
  result[date][staff] ||= []
  result[date][staff] << task
end
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3 Comments

Reads easy, I'll give it a go. Nice alternative approach. ||= is nice, Really appreciated!
Don't ask why I use this old version :D
Works perfectly fine!

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