Module: ExtraLoop::Storage::IdKey

Included in:
Model
Defined in:
lib/extraloop/redis-storage/id_key.rb

Overview

Public: Provides a convinient mechanism to override Ohm’s default id assignment mechanism and replace numeric, auto-increment ids with more readable, unique keys

Constant Summary collapse

ID_FORMAT =

Internal: A regex to be used in order to valid the key string format

/^[a-zA-Z\-\_]+$/
KEY_SEPARATOR =

Internal: The separator to be used when record id keys.

':'

Instance Method Summary collapse

Instance Method Details

#[](id, attributes = {}) ⇒ Object

Public: Turns ‘Ohm::Model::[]’ into a powerful method which behaves somehow like Rails’ “find_or_create”/“find_or_update”.

If the record does not exist, it will be created (or just initialised) with the provided attribute values. If the record does exist already, and no attributes are provided, the record will be fetched and returned. If the record exists and the attribute hash is provided, this method will try to update it with the provided attribute values.

TODO: consider privatising/removing the #save and the #create method for models extended with this module.

id - An alphanumeric id string, which will be used generate the key string to store the record into Redis. attributes - An hash of record attributes.

Examples

user = User[‘bob’, => ‘Robert Plancton’, :website => ‘planktonic.net’] user.id

> ‘User:bob’

User == user

> true

user = User[‘bob’, {:website => ‘planctoinic.net’ }] user.website

> ‘planctoinic.net’

Returns a Ohm record. Raises an ‘ArgumentError’ if the provided id string does not match the ID_FORMAT (e.g. if it contains non-alphanumeric characters’).



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# File 'lib/extraloop/redis-storage/id_key.rb', line 46

def [](id, attributes={})
  # automatically strip prefix from id
  id = id.to_s.gsub(prefix + KEY_SEPARATOR, '')
  raise ArgumentError.new "Invalid id '#{id}'" unless id =~ ID_FORMAT
  id = [prefix, id].reject(&:empty?).join(KEY_SEPARATOR)

  if record = super(id)
    record.update(attributes) if attributes.any?
    record
  else 
    create(attributes.merge(:id => id))
  end
end

#prefix(attributes = {}) ⇒ Object

Public: Prefixes the provided record id with a namespace.

While default behviour is to prepend the record’s model class name to id string, it is possible to override this method so that the generated record id key will include other attributes (see example below).

attributes - The attributes hash

Examples

# Overrides the default prefix method so that the ‘locale’ attribute will be included as part of the # record id prefix.

include ExtraLoop::Storage

class Entry < Record

extend IdKey
attribute :locale

def self::prefix(attrs={})
  [self.name, attrs.fetch(:locale, 'en')].join(IdKey::KEY_SEPARATOR)
end

end

entry = Entry entry.id

> ‘Entry:en:Hello-world’

Returns the record id key.



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# File 'lib/extraloop/redis-storage/id_key.rb', line 91

def prefix(attributes={})
  self.name
end