Class: Redis::Objects::Model

Inherits:
Object
  • Object
show all
Includes:
Redis::Objects
Defined in:
lib/redis-objects-model.rb,
lib/redis-objects-model/version.rb

Overview

The simplest possible Model to use with redis-objects.

The minimum requirement for a class to be usable as a model with redis-objects is that it must provide an id attribute. So here is a base class that provides an id attribute - lazily yet atomically allocated using Redis, of course.

A few convenience methods are provided to allow you to check whether an id has been allocated, to do idiomatic ‘find’ type lookups, and to create with immediate id allocation.

Constant Summary collapse

VERSION = 
"1.0.1"

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(id = nil) ⇒ Model

Create an instance of the model.

If the id parameter is not nil, the model will be for the object with that id. Otherwise, you are creating a new object and a new id will be allocated atomically as needed.



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# File 'lib/redis-objects-model.rb', line 34

def initialize(id = nil)
  @id = id
end

Class Method Details

.create ⇒ Object

Create a new object, persisting it immediately.



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# File 'lib/redis-objects-model.rb', line 69

def self.create
  i = self.new
  i.id
  i
end

.find(id) ⇒ Object

Look up an object by id.



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# File 'lib/redis-objects-model.rb', line 77

def self.find(id)
  self.new id
end

Instance Method Details

#id ⇒ Object

Retrieve the id of the object.

If the instance is referencing an existing object, the id of that object will be returned. Otherwise a new id will be allocated (and immediately saved).

In other words, accessing the id attribute is basically equivalent to persisting the object.



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# File 'lib/redis-objects-model.rb', line 47

def id
  @id || @id = self.redis.incr(self.redis_objects_model_next_id)
end

#new_record? ⇒ Boolean

Returns true if no id has been allocated for this object yet.



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# File 'lib/redis-objects-model.rb', line 57

def new_record?
  @id.nil?
end

#persisted? ⇒ Boolean

Returns false if no id has been allocated for this object yet.



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# File 'lib/redis-objects-model.rb', line 63

def persisted?
  !new_record?
end

#redis_objects_model_next_id ⇒ Object

The name of the redis counter which will be used to allocate keys.



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# File 'lib/redis-objects-model.rb', line 24

def redis_objects_model_next_id
  "#{self.class.redis_prefix}:next_id"
end