How I can delete key and value in array of hash?

Question

I need delete all key created_at and updated_at in array of hashs . My hash looks like :

assessment_with_desc = {
  "id": 1,
  "name": "First assessment",
  "created_at": "2020-03-14T20:13:27.006Z",
  "updated_at": "2020-03-14T20:13:27.006Z",
  "description_with_child_models": [
    {
      "id": 3,
      "title": "First category",
      "created_at": "2020-02-20T15:32:46.379Z",
      "updated_at": "2020-03-14T20:16:11.530Z",
      "accessment_id": 1,
      "sub_categories": [
      {
        "id": 1,
        "title": "First sub_category",
        "category_id": 3,
        "created_at": "2020-02-20T15:40:49.793Z",
        "updated_at": "2020-02-20T15:40:49.793Z",
        "stages": [
        {
          "id": 5,
          "title": "First stage",
          "sub_category_id": 1,
          "created_at": "2020-02-20T15:44:10.603Z",
          "updated_at": "2020-02-20T15:44:10.603Z"
        }
       ]
      }
     ]
    }
  ]
}

I did it, but it work only in this case assessment_with_desc.delete('created_at') and assessment_with_desc.delete('updated_at'):

assessment_with_desc.delete('created_at')
assessment_with_desc.delete('updated_at')
assessment_with_desc['description_with_child_models'].delete('created_at')
assessment_with_desc['description_with_child_models'].delete('updated_at')
assessment_with_desc['description_with_child_models'][0]['sub_categories'].delete('created_at')
assessment_with_desc['description_with_child_models'][0]['sub_categories'].delete('updated_at')
assessment_with_desc['description_with_child_models'][0]['sub_categories'][0]['stages'].delete('created_at')
assessment_with_desc['description_with_child_models'][0]['sub_categories'][0]['stages'].delete('updated_at')

Welcome to Stack Overflow! I’m not sure what you’re trying to do, here. You do seem to be trying to remove a lot of values, tho. Perhaps you could select the keys you want to keep using Hash#slice, instead? — AJFaraday
– AJFaraday, Commented Mar 17, 2020 at 10:15

Sebastián Palma · Accepted Answer · 2020-03-17 12:02:05Z

1

You can recursively invoke a function to remove the key/value in case the key is equal to :created_at or :updated_at:

def recursively_delete_timestamps(object)
  object.transform_values do |value|
    next value unless value.is_a?(Array)

    value.map do |inner_hash|
      recursively_delete_timestamps(inner_hash)
    end
  end.reject do |key, _|
    key.in?(%i[created_at updated_at])
  end
end

recursively_delete_timestamps(assessment_with_desc)
# {:id=>1,
#  :name=>"First assessment",
#  :description_with_child_models=>
#   [{:id=>3,
#     :title=>"First category",
#     :accessment_id=>1,
#     :sub_categories=>
#      [{:id=>1,
#        :title=>"First sub_category",
#        :category_id=>3,
#        :stages=>[{:id=>5, :title=>"First stage", :sub_category_id=>1}]}]}]}

Notice, the hash remains unchanged. Nor transform_values, map or reject modify the original object, but return a new one.

edited Mar 17, 2020 at 12:02

answered Mar 17, 2020 at 10:26

Sebastián Palma

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3 Comments

Rajagopalan Over a year ago

What is this .in? ?

Sebastián Palma Over a year ago

It's a Rails method to check if the receiver is included in the object passed as a parameter.

Rajagopalan Over a year ago

Oh okay. I am knowing rails that's why the question.

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