Class: Sohm::Model

Inherits:
Object
  • Object
show all
Defined in:
lib/sohm.rb,
lib/sohm/json.rb

Overview

The base class for all your models. In order to better understand it, here is a semi-realtime explanation of the details involved when creating a User instance.

Example:

class User < Sohm::Model
  attribute :name
  index :name

  attribute :email
  unique :email

  counter :points

  set :posts, :Post
end

u = User.create(:name => "John", :email => "[email protected]")
u.incr :points
u.posts.add(Post.create)

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(atts = {}) ⇒ Model

Initialize a model using a dictionary of attributes.

Example:

u = User.new(:name => "John")



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# File 'lib/sohm.rb', line 903

def initialize(atts = {})
  @attributes = {}
  @serial_attributes = {}
  @serial_attributes_changed = false
  update_attributes(atts)
end

Instance Attribute Details

#cas_token ⇒ Object

Returns the value of attribute cas_token.



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# File 'lib/sohm.rb', line 922

def cas_token
  @cas_token
end

#id ⇒ Object

Access the ID used to store this model. The ID is used together with the name of the class in order to form the Redis key.

Different from ohm, id must be provided by the user in sohm, if you want to use auto-generated id, you can include Sohm::AutoId module.

Raises:



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# File 'lib/sohm.rb', line 916

def id
  raise MissingID if not defined?(@id)
  @id
end

Class Method Details

.[](id) ⇒ Object

Retrieve a record by ID.

Example:

u = User.create
u == User[u.id]
# =>  true



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# File 'lib/sohm.rb', line 540

def self.[](id)
  new(:id => id).load! if id && exists?(id)
end

.attribute(name, cast = nil) ⇒ Object

The bread and butter macro of all models. Basically declares persisted attributes. All attributes are stored on the Redis hash.

class User < Sohm::Model
  attribute :name
end

user = User.new(name: "John")
user.name
# => "John"

user.name = "Jane"
user.name
# => "Jane"

A lambda can be passed as a second parameter to add typecasting support to the attribute.

class User < Sohm::Model
  attribute :age, ->(x) { x.to_i }
end

user = User.new(age: 100)

user.age
# => 100

user.age.kind_of?(Integer)
# => true

Check rubydoc.info/github/cyx/ohm-contrib#Ohm__DataTypes to see more examples about the typecasting feature.



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# File 'lib/sohm.rb', line 798

def self.attribute(name, cast = nil)
  if serial_attributes.include?(name)
    raise ArgumentError,
          "#{name} is already used as a serial attribute."
  end
  attributes << name unless attributes.include?(name)

  if cast
    define_method(name) do
      cast[@attributes[name]]
    end
  else
    define_method(name) do
      @attributes[name]
    end
  end

  define_method(:"#{name}=") do |value|
    @attributes[name] = value
  end
end

.collection(name, model, reference = to_reference) ⇒ Object

A macro for defining a method which basically does a find.

Example:

class Post < Sohm::Model
  reference :user, :User
end

class User < Sohm::Model
  collection :posts, :Post
end

# is the same as

class User < Sohm::Model
  def posts
    Post.find(:user_id => self.id)
  end
end



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# File 'lib/sohm.rb', line 703

def self.collection(name, model, reference = to_reference)
  define_method name do
    model = Utils.const(self.class, model)
    model.find(:"#{reference}_id" => id)
  end
end

.counter(name) ⇒ Object

Declare a counter. All the counters are internally stored in a different Redis hash, independent from the one that stores the model attributes. Counters are updated with the ‘incr` and `decr` methods, which interact directly with Redis. Their value can’t be assigned as with regular attributes.

Example:

class User < Sohm::Model
  counter :points
end

u = User.create
u.incr :points

u.points
# => 1

Note: You can’t use counters until you save the model. If you try to do it, you’ll receive an Sohm::MissingID error.



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# File 'lib/sohm.rb', line 870

def self.counter(name)
  counters << name unless counters.include?(name)

  define_method(name) do
    return 0 if new?

    redis.call("HGET", key[:_counters], name).to_i
  end
end

.create(atts = {}) ⇒ Object

Create a new model, notice that under Sohm’s circumstances, this is no longer a syntactic sugar for Model.new(atts).save



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# File 'lib/sohm.rb', line 887

def self.create(atts = {})
  new(atts).save
end

.exists?(id) ⇒ Boolean

Check if the ID exists within <Model>:all.

Returns:

  • (Boolean) 


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# File 'lib/sohm.rb', line 561

def self.exists?(id)
  redis.call("EXISTS", key[id]) == 1
end

.fetch(ids) ⇒ Object

Retrieve a set of models given an array of IDs.

Example:

User.fetch([1, 2, 3])



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# File 'lib/sohm.rb', line 619

def self.fetch(ids)
  all.fetch(ids)
end

.find(dict) ⇒ Object

Find values in indexed fields.

Example:

class User < Sohm::Model
  attribute :email

  attribute :name
  index :name

  attribute :status
  index :status

  index :provider
  index :tag

  def provider
    email[/@(.*?).com/, 1]
  end

  def tag
    ["ruby", "python"]
  end
end

u = User.create(name: "John", status: "pending", email: "[email protected]")
User.find(provider: "me", name: "John", status: "pending").include?(u)
# => true

User.find(:tag => "ruby").include?(u)
# => true

User.find(:tag => "python").include?(u)
# => true

Due to restrictions in Codis, we only support single-index query. If you want to query based on multiple fields, you can make an index based on all the fields.



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# File 'lib/sohm.rb', line 603

def self.find(dict)
  keys = filters(dict)

  if keys.size == 1
    Sohm::Set.new(keys.first, key, self)
  else
    raise NotSupported
  end
end

.index(attribute) ⇒ Object

Index any method on your model. Once you index a method, you can use it in ‘find` statements.



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# File 'lib/sohm.rb', line 625

def self.index(attribute)
  indices << attribute unless indices.include?(attribute)
end

.key ⇒ Object

Returns the namespace for all the keys generated using this model.

Example:

class User < Sohm::Model
end

User.key == "User"
User.key.kind_of?(String)
# => true

User.key.kind_of?(Nido)
# => true

To find out more about Nido, see:

http://github.com/soveran/nido



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# File 'lib/sohm.rb', line 528

def self.key
  Nido.new(self.name)
end

.list(name, model) ⇒ Object

Declare an Sohm::List with the given name.

Example:

class Comment < Sohm::Model
end

class Post < Sohm::Model
  list :comments, :Comment
end

p = Post.create
p.comments.push(Comment.create)
p.comments.unshift(Comment.create)
p.comments.size == 2
# => true

Note: You can’t use the list until you save the model. If you try to do it, you’ll receive an Sohm::MissingID error.



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# File 'lib/sohm.rb', line 674

def self.list(name, model)
  track(name)

  define_method name do
    model = Utils.const(self.class, model)

    Sohm::List.new(key[name], model.key, model)
  end
end

.mutex ⇒ Object 



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# File 'lib/sohm.rb', line 503

def self.mutex
  Sohm.mutex
end

.redis ⇒ Object 



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# File 'lib/sohm.rb', line 499

def self.redis
  defined?(@redis) ? @redis : Sohm.redis
end

.redis=(redis) ⇒ Object 



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# File 'lib/sohm.rb', line 495

def self.redis=(redis)
  @redis = redis
end

.reference(name, model) ⇒ Object

A macro for defining an attribute, an index, and an accessor for a given model.

Example:

class Post < Sohm::Model
  reference :user, :User
end

# It's the same as:

class Post < Sohm::Model
  attribute :user_id
  index :user_id

  def user
    User[user_id]
  end

  def user=(user)
    self.user_id = user.id
  end

  def user_id=(user_id)
    self.user_id = user_id
  end
end



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# File 'lib/sohm.rb', line 738

def self.reference(name, model)
  reader = :"#{name}_id"
  writer = :"#{name}_id="

  attributes << reader unless attributes.include?(reader)

  index reader

  define_method(reader) do
    @attributes[reader]
  end

  define_method(writer) do |value|
    @attributes[reader] = value
  end

  define_method(:"#{name}=") do |value|
    send(writer, value ? value.id : nil)
  end

  define_method(name) do
    model = Utils.const(self.class, model)
    model[send(reader)]
  end
end

.serial_attribute(name, cast = nil) ⇒ Object

Attributes that require CAS property



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# File 'lib/sohm.rb', line 821

def self.serial_attribute(name, cast = nil)
  if attributes.include?(name)
    raise ArgumentError,
          "#{name} is already used as a normal attribute."
  end
  serial_attributes << name unless serial_attributes.include?(name)

  if cast
    define_method(name) do
      # NOTE: This is a temporary solution, since we might use
      # composite objects (such as arrays), which won't always
      # do a reset
      @serial_attributes_changed = true
      cast[@serial_attributes[name]]
    end
  else
    define_method(name) do
      @serial_attributes_changed = true
      @serial_attributes[name]
    end
  end

  define_method(:"#{name}=") do |value|
    @serial_attributes_changed = true
    @serial_attributes[name] = value
  end
end

.set(name, model) ⇒ Object

Declare an Sohm::Set with the given name.

Example:

class User < Sohm::Model
  set :posts, :Post
end

u = User.create
u.posts.empty?
# => true

Note: You can’t use the set until you save the model. If you try to do it, you’ll receive an Sohm::MissingID error.



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# File 'lib/sohm.rb', line 644

def self.set(name, model)
  track(name)

  define_method name do
    model = Utils.const(self.class, model)

    Sohm::MutableSet.new(key[name], model.key, model)
  end
end

.synchronize(&block) ⇒ Object 



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# File 'lib/sohm.rb', line 507

def self.synchronize(&block)
  mutex.synchronize(&block)
end

.to_proc ⇒ Object

Retrieve a set of models given an array of IDs.

Example:

ids = [1, 2, 3]
ids.map(&User)

Note: The use of this should be a last resort for your actual application runtime, or for simply debugging in your console. If you care about performance, you should pipeline your reads. For more information checkout the implementation of Sohm::List#fetch.



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# File 'lib/sohm.rb', line 556

def self.to_proc
  lambda { |id| self[id] }
end

.track(name) ⇒ Object

Keep track of ‘key` and remove when deleting the object.



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# File 'lib/sohm.rb', line 881

def self.track(name)
  tracked << name unless tracked.include?(name)
end

Instance Method Details

#==(other) ⇒ Object Also known as: eql?

Check for equality by doing the following assertions:

  1. That the passed model is of the same type.

  2. That they represent the same Redis key.



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# File 'lib/sohm.rb', line 929

def ==(other)
  other.kind_of?(model) && other.key == key
rescue MissingID
  false
end

#attributes ⇒ Object

Returns a hash of the attributes with their names as keys and the values of the attributes as values. It doesn’t include the ID of the model.

Example:

class User < Sohm::Model
  attribute :name
end

u = User.create(:name => "John")
u.attributes
# => { :name => "John" }



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# File 'lib/sohm.rb', line 1003

def attributes
  @attributes
end

#counters ⇒ Object 



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# File 'lib/sohm.rb', line 1011

def counters
  hash = {}
  self.class.counters.each do |name|
    hash[name] = 0
  end
  return hash if new?
  redis.call("HGETALL", key[:_counters]).each_slice(2).each do |pair|
    hash[pair[0].to_sym] = pair[1].to_i
  end
  hash
end

#decr(att, count = 1) ⇒ Object

Decrement a counter atomically. Internally uses HINCRBY.



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# File 'lib/sohm.rb', line 968

def decr(att, count = 1)
  incr(att, -count)
end

#delete ⇒ Object

Delete the model, including all the following keys:

  • <Model>:<id>

  • <Model>:<id>:_counters

  • <Model>:<id>:<set name>

If the model has uniques or indices, they’re also cleaned up.



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# File 'lib/sohm.rb', line 1153

def delete
  memo_key = key["_indices"]
  commands = [["DEL", key], ["DEL", memo_key], ["DEL", key["_counters"]]]
  index_list = redis.call("SMEMBERS", memo_key)
  index_list.each do |index_key|
    commands << ["SREM", index_key, id]
  end
  model.tracked.each do |tracked_key|
    commands << ["DEL", key[tracked_key]]
  end

  model.synchronize do
    commands.each do |command|
      redis.queue(*command)
    end
    redis.commit
  end

  return self
end

#hash ⇒ Object

Return a value that allows the use of models as hash keys.

Example:

h = {}

u = User.new

h[:u] = u
h[:u] == u
# => true



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# File 'lib/sohm.rb', line 984

def hash
  new? ? super : key.hash
end

#incr(att, count = 1) ⇒ Object

Increment a counter atomically. Internally uses HINCRBY.



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# File 'lib/sohm.rb', line 963

def incr(att, count = 1)
  redis.call("HINCRBY", key[:_counters], att, count)
end

#key ⇒ Object

Returns the namespace for the keys generated using this model. Check ‘Sohm::Model.key` documentation for more details.



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# File 'lib/sohm.rb', line 893

def key
  model.key[id]
end

#load! ⇒ Object

Preload all the attributes of this model from Redis. Used internally by ‘Model::[]`.



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# File 'lib/sohm.rb', line 937

def load!
  update_attributes(Utils.dict(redis.call("HGETALL", key))) if id
  @serial_attributes_changed = false
  return self
end

#new? ⇒ Boolean

Returns true if the model is not persisted. Otherwise, returns false.

Example:

class User < Sohm::Model
  attribute :name
end

u = User.new(:name => "John")
u.new?
# => true

u.save
u.new?
# => false

Returns:

  • (Boolean) 


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# File 'lib/sohm.rb', line 958

def new?
  !(defined?(@id) && model.exists?(id))
end

#refresh_indices ⇒ Object

Refresh model indices



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# File 'lib/sohm.rb', line 1102

def refresh_indices
  memo_key = key["_indices"]
  # Add new indices first
  commands = fetch_indices.each_pair.map do |field, vals|
    vals.map do |val|
      index_key = model.key["_indices"][field][val]
      [["SADD", memo_key, index_key], ["SADD", index_key, id]]
    end
  end.flatten(2)

  model.synchronize do
    commands.each do |command|
      redis.queue(*command)
    end
    redis.commit
  end

  # Remove old indices
  index_set = ::Set.new(redis.call("SMEMBERS", memo_key))
  # Here we are fetching the latest model to avoid concurrency issue
  valid_list = model[id].send(:fetch_indices).each_pair.map do |field, vals|
    vals.map do |val|
      model.key["_indices"][field][val]
    end
  end.flatten(1)
  valid_set = ::Set.new(valid_list)
  diff_set = index_set - valid_set
  if diff_set.size > 0
    diff_list = diff_set.to_a
    commands = diff_list.map do |key|
      ["SREM", key, id]
    end + [["SREM", memo_key] + diff_list]

    model.synchronize do
      commands.each do |command|
        redis.queue(*command)
      end
      redis.commit
    end
  end
  true
end

#save ⇒ Object

Persist the model attributes and update indices and unique indices. The ‘counter`s and `set`s are not touched during save.

Example:

class User < Sohm::Model
  attribute :name
end

u = User.new(:name => "John").save
u.kind_of?(User)
# => true



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# File 'lib/sohm.rb', line 1072

def save
  if serial_attributes_changed
    response = script(LUA_SAVE, 1, key,
      sanitize_attributes(serial_attributes).to_msgpack,
      cas_token,
      sanitize_attributes(attributes).to_msgpack)

    if response.is_a?(RuntimeError)
      if response.message =~ /cas_error/
        raise CasViolation
      else
        raise response
      end
    end

    @cas_token = response
    @serial_attributes_changed = false
  else
    redis.call("HSET", key, "_ndata",
               sanitize_attributes(attributes).to_msgpack)
  end

  if Sohm.refresh_indices_inline
    refresh_indices
  end

  return self
end

#script(file, *args) ⇒ Object

Run lua scripts and cache the sha in order to improve successive calls.



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# File 'lib/sohm.rb', line 1176

def script(file, *args)
  response = nil

  if Sohm.enable_evalsha
    response = redis.call("EVALSHA", LUA_SAVE_DIGEST, *args)
    if response.is_a?(RuntimeError)
      if response.message =~ /NOSCRIPT/
        response = nil
      end
    end
  end

  response ? response : redis.call("EVAL", LUA_SAVE, *args)
end

#serial_attributes ⇒ Object 



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# File 'lib/sohm.rb', line 1007

def serial_attributes
  @serial_attributes
end

#to_hash ⇒ Object

Export the ID of the model. The approach of Ohm is to whitelist public attributes, as opposed to exporting each (possibly sensitive) attribute.

Example:

class User < Sohm::Model
  attribute :name
end

u = User.create(:name => "John")
u.to_hash
# => { :id => "1" }

In order to add additional attributes, you can override ‘to_hash`:

class User < Sohm::Model
  attribute :name

  def to_hash
    super.merge(:name => name)
  end
end

u = User.create(:name => "John")
u.to_hash
# => { :id => "1", :name => "John" }



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# File 'lib/sohm.rb', line 1051

def to_hash
  attrs = {}
  attrs[:id] = id unless new?

  return attrs
end

#to_json(*args) ⇒ Object

Export a JSON representation of the model by encoding ‘to_hash`.



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# File 'lib/sohm/json.rb', line 6

def to_json(*args)
  to_hash.to_json(*args)
end

#update(attributes) ⇒ Object

Update the model attributes and call save.

Example:

User[1].update(:name => "John")

# It's the same as:

u = User[1]
u.update_attributes(:name => "John")
u.save



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# File 'lib/sohm.rb', line 1203

def update(attributes)
  update_attributes(attributes)
  save
end

#update_attributes(atts) ⇒ Object

Write the dictionary of key-value pairs to the model.



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# File 'lib/sohm.rb', line 1209

def update_attributes(atts)
  unpack_attrs(atts).each { |att, val| send(:"#{att}=", val) }
end