How to fix keys in a jsonb field

Question

I have a table with one jsonb field. I want that field to have onlye three keys, say the table schema is

name: string dob: date personal_data: jsonb

i want personal_data to have only three keys personal_data: { mothers_name: '', father_name: '', random_key: ''

}

if i try to save some other key, it should show an error. I am using rails, any way to achieve this

Answer 1

this will handle two specific keys and any random 3rd key. If you want 3 specific keys only add the third key to the array and (self....).count == 3 instead of 2

On yourmodel.rb

before_save :check_personal_data

keys_to_always_match = [ :mothers_name, :father_name ]

def check_personal_data
  (self.personal_data.keys & keys_to_always_match).count == 2 && self.personal_data.count == 3 
end

You'll probably also want to add a default value to the migration:

t.jsonb :personal_data, default: { mothers_name: '', father_name: '', random_key: '' }

The elegant solution for the key matching comes from:

Testing if a hash has any of a number of keys