Class: Rodbot::Db

Inherits:
Object
  • Object
show all
Defined in:
lib/rodbot/db.rb,
lib/rodbot/db/hash.rb,
lib/rodbot/db/redis.rb

Overview

Uniform key/value database interface for various backends

Keys can be namespaced using the colon as separator:

  • ‘color’ - color key without namespace

  • ‘bike:color’ - color key within the bike namespace

  • ‘vehicle:bike:color’ - color key within… you get the idea

Furthermore, keys can be entered either as colon separated keys or as list of symbols. The following are therefore equivalent:

Rodbot.db.get('vehicle:bike:color')
Rodbot.db.get(:vehicle, :bike, :color)

Same goes for the star wildcard which is only allowed last:

Rodbot.db.scan('vehicle:*')
Rodbot.db.scan(:vehicle, :*)

The interface is simple and straightforward:

Please note that JSON is used to serialize which has an influence on what you get back after deserialization:

  • Primitive types such as String, Integer or TrueClass are preserved.

  • Any other object is converted to String, incuding…

  • Symbol values are converted to String

  • Symbol elements in an array are converted to String

  • Symbol values in a hash are converted to String

However, hash keys are always converted to Symbol - mainly because Rubyland favours Symbol keys over String keys for visual reasons.

Examples:

Set a value

Rodbot.db.set(:name) { 'John' }

Set a value which expires after 30 seconds

Rodbot.db.set(:name, expires_in: 30) { 'John' }

Replace an existing value

Rodbot.db.set(:name) { 'John' }
Rodbot.db.set(:name) { 'Bob' }   # replaces John with Bob

Update an existing value

Rodbot.db.set(:name) { 'John' }
Rodbot.db.set(:name) { |n| "#{n} Doe" }   # replaces John with John Doe

Get a value

Rodbot.db.set(:name) { 'John' }
Rodbot.db.get(:name)   # => 'John'

Delete a value

Rodbot.db.set(:name) { 'John' }
Rodbot.db.delete(:name)   # => 'John'
Rodbot.db.get(:name)      # => nil

Scan for keys

Rodbot.db.set(:first_name) { 'John' }
Rodbot.db.set(:last_name) { 'Doe' }
Rodbot.db.scan(:*)   # => [:first_name, :last_name]

Delete all keys

Rodbot.db.flush

Defined Under Namespace

Modules: Hash, Redis

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(url) ⇒ Db

Returns a new instance of Db.

Parameters:

  • url (String) —

    connection URL of the backend



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# File 'lib/rodbot/db.rb', line 76

def initialize(url)
  @url = url
  extend "rodbot/db/#{url.split('://').first}".constantize
end

Instance Attribute Details

#url ⇒ Object (readonly)

Returns the value of attribute url.



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# File 'lib/rodbot/db.rb', line 73

def url
  @url
end