Always use strings keys in JSON in languages that support symbol keys

This is part of the Semicolon&Sons Code Diary - consisting of lessons learned on the job. You're in the data category.

Last Updated: 2021-05-15

A script of mine whose job was to match (SQL) database objects with JSON data failed, in the sense of returning all nils in the mapped output.

Here is the code:

tutor_data = JSON.read("tutors.json")

Tutor.where(state: "accepted").map do |tutor|
  # The problematic line...
  tutor_data.find {|e| e[:id] == tutor.id}
end

The issue was that technically speaking the :id fields in the (rubyified) JSON was nil - all that was available was the "id" field - i.e. a string field, not a symbol field (which are standard with Ruby's hashes, themselves deceptively JSON-like structures).

It is better, therefore, to keep it simple and always use strings keys when working with JSON.

tutor_data.find {|e| e["id"] == tutor.id}