Mapping example

mapping.txt

# user = User.where(id: 1369).first
# contact_ids = Contact.where(creator_id: 1369).pluck(:id).sort
# kids = Kid.where("contact_id IN (:contact_ids)", contact_ids: contact_ids)

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old_db_kids = Kid.where("id IN (?)", kid_ids)
old_db_kid_ids = [1, 2, 3, 4, 5, 6, 7]

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new_db_kids = Kid.where("id IN (?)", kid_ids)
new_db_kid_ids = [4, 5, 6, 7]

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missing_kid_ids = old_db_kid_ids - new_db_kid_ids
missing_kid_ids = [1, 2, 3]

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contact_for_missing_contact_ids = Kid.where(id: missing_kid_ids).pluck(:contact_id)
contact_for_missing_contact_ids = [101, 102, 103]

contact_for_missing_contacts_old_db = Contact.where(id: contact_for_missing_contact_ids)
contact_for_missing_contacts_old_db = [101, 102, 103]

contact_for_missing_contacts_new_db = Contact.where(id: contact_for_missing_contact_ids)
contact_for_missing_contacts_new_db = []


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suppose contact with id 103 is resotored with new id.
c_array = contact_for_missing_contacts_old_db.pluck_all(:id, :first_name, :last_name)
c_array = [[101, "Aaron", "Moy"], [102, "Abby", "Grenke"], [103, "Abhay", "Raj"]]

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map_hash = Hash.new

c_array.each{|c| map_hash[c[0]] = Contact.where(creator_id: 1369, first_name: c[1], last_name: c[2]).first.try(:id) }

map_hash = { 101=>nil, 102=>nil, 103=>113 }

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OLD_NEW_CONTACT_IDS = { 101=>101, 102=>101, 103=>113 }

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file = "#{Rails.root}/public/jeff_contacts_kids.csv"

CSV.open( file, 'w') do |writer|
  kids.each do |kid|
    next unless kid.present?

    data_array = [
        kid.id,
        kid.name,
        OLD_NEW_CONTACT_IDS[kid.contact_id]
        kid.created_at
        kid.updted_at
    ]
    writer << data_array
  end
end


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