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A way to receive and retrieve non-migrated fields using a SQL database with JSON field support. The only thing you need to do is create a JSON column called `fields` in the table and include this module into your model.
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| # frozen_string_literal: true | |
| # A module to abstract a noSQL aproach into SQL records, using a `fields` | |
| # JSON column. | |
| module CustomFields | |
| # Overriding `method_missing` does the magic of assigning an absent field | |
| # into `.fields` JSON as a key-value pair, or recovering it's value if exists. | |
| def method_missing(meth, *args, &block) | |
| raise NoMethodError, "#{table_name} should have a `fields` JSON column" unless can_no_sqlize? | |
| no_sqlize(meth, *args, &block) | |
| rescue StandardError | |
| super | |
| end | |
| # Used to map which methods can be called in the instance, it is based on | |
| # the premisse that you can always assign a value to any field and recover | |
| # only existing fields or the ones that are in the `.fields` JSON. | |
| def respond_to_missing?(method_name, include_private = false) | |
| method_name.to_s.ends_with?('=') || | |
| try(:fields).try(:[], method_name.to_s).present? || | |
| super | |
| end | |
| # Overriding a ActiveRecord method that is used in `.create` and `.update` | |
| # methods to assign a value into an attribute. | |
| def _assign_attribute(key, value) | |
| initialize_fields | |
| if value.nil? | |
| public_send('fields=', try(:fields).try(:except, key)) | |
| else | |
| public_send("#{key}=", value) | |
| end | |
| end | |
| private | |
| # Checks for `.fields` presence and initializes it. | |
| def initialize_fields | |
| try(:fields=, {}) unless try(:fields).present? | |
| end | |
| # The behavior that a noSQL method should have... | |
| def no_sqlize(meth, *args, &_block) | |
| initialize_fields | |
| if meth.to_s.ends_with?('=') | |
| fields[meth.to_s.chomp('=')] = args.first | |
| else | |
| try(:fields).try(:[], meth.to_s) | |
| end | |
| end | |
| # Checks if requirements are met for the feature | |
| def can_no_sqlize? | |
| self.class.column_names.include?('fields') | |
| end | |
| end |
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