setting hstore in rails4, dynamic key/values

Question

I\'m playing around with Hstore for the first time in a rails4 app, and I am using javascript in a form to build out dynamic form fields for the hstore column (:schema)

Answer 1

Here's a way that also allows deleting of the hstore keys by submitting empty parameters.

In your ApplicationController add this method:

# Returns the hstore keys to be whitelisted.
#
# @param key [Symbol] the name of the hstore field
# @param params [Hash] the parameters for the hstore field
#
# @return [{Symbol => Array}, Symbol]
def permit_hstore_params(key, hstore_params)
  keys = hstore_params.try(:keys)

  # Return key if params are empty, 
  # this allows the hstore key to be removed.
  return key if keys.blank?

  # Otherwise, return the keys to be whitelisted
  { key => keys }
end

Example:

class DynamicRecord < ActiveRecord::Base
  store_accessor :metadata
end

class DynamicRecordController < ApplicationController
  # ...

  def dynamic_model_params
    params
      .require(:dynamic_model)
      .permit(:name, permit_hstore_params(:metadata, params[:dynamic_model][:metadata]))
  end
end