How to get and remove duplicate customer

[nvtin]

Goal:

• Check and get all customer which is duplicated on database
• Remove duplicate customers, keep the one which have most fields is not null
• If all of them have same fields, keep the first.

How to do:

1. To get customers which have same email
   Customer.select('email, count(email)').group('email').having('count(email) > 1')

2. Count fields is not null on customer

   def count_present_attributes(customer)
   count = 0
   customer.attributes.keys.each do |k|
     count += 1 if customer.send(k).present? 
   end
   count
   end
   

3. Destroy duplicate customers

def delete_duplicate_customer
    Customer.select('email, count(email)').group('email').having('count(email) > 1').each do |customer|
      customers_with_dup = Customer.where(email: customer.email)
      customer_to_keep = customers_with_dup.max_by{|cust| count_present_attributes(cust)}
      customers_to_delete = customers_with_dup.reject{|item| item === customer_to_keep}
      customers_to_delete.each(&:destroy!)
    end
 end