Module: Cassie::Model

Extended by:
ActiveModel::Callbacks, ActiveSupport::Concern
Includes:
ActiveModel::Model, ActiveModel::Validations, ActiveModel::Validations::Callbacks
Defined in:
lib/cassie/model.rb

Overview

This module provides a simple interface for models backed by Cassandra tables.

Cassandra is very limited in how data can be accessed efficiently so this code is intentionally not designed as a full fledged DSL with all the nifty features of ActiveRecord. Doing so will only get you into trouble when you run into the limits of Cassandra data structures.

It implements ActiveModel::Model and supports ActiveModel callbacks on :create, :update, :save, and :destroy as well as ActiveModel validations.

Example:

class Thing
  include Cassie::Model

  self.table_name = "things"
  self.keyspace = "test"
  self.primary_key = [:owner, :id]

  column :owner, :int
  column :id, :int, :as => :identifier
  column :val, :varchar, :as => :value

  ordering_key :id, :desc

  validates_presence_of :id, :value

  before_save do
    ...
  end
end

Defined Under Namespace

Modules: ClassMethods

Instance Method Summary collapse

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/cassie/model.rb', line 498

def ==(other)
  eql?(other)
end

#attributes ⇒ Object

Returns a hash of column to values. Column names will be symbols.



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# File 'lib/cassie/model.rb', line 481

def attributes
  hash = {}
  self.class.column_names.each do |name|
    hash[name] = send(name)
  end
  hash
end

#counter_table? ⇒ Boolean

Return true if the table is used for a counter.

Returns:

  • (Boolean) 


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# File 'lib/cassie/model.rb', line 432

def counter_table?
  !!self.class._counter_table
end

#destroy ⇒ Object

Delete a record and call the destroy callbacks.



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# File 'lib/cassie/model.rb', line 472

def destroy
  run_callbacks(:destroy) do
    self.class.connection.delete(self.class.full_table_name, key_hash)
    @persisted = false
    true
  end
end

#eql?(other) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/cassie/model.rb', line 494

def eql?(other)
  other.is_a?(self.class) && other.key_hash == key_hash
end

#initialize(attributes = {}) ⇒ Object 



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# File 'lib/cassie/model.rb', line 421

def initialize(attributes = {})
  super
  @persisted = false
end

#key_hash ⇒ Object

Returns the primary key as a hash



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# File 'lib/cassie/model.rb', line 503

def key_hash
  hash = {}
  self.class.primary_key.each do |key|
    hash[key] = self.send(key)
  end
  hash
end

#persisted? ⇒ Boolean

Return true if the record has been persisted to Cassandra.

Returns:

  • (Boolean) 


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# File 'lib/cassie/model.rb', line 427

def persisted?
  @persisted
end

#persistence_ttl ⇒ Object

Subclasses can override this method to provide a TTL on the persisted record.



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# File 'lib/cassie/model.rb', line 490

def persistence_ttl
  nil
end

#save(validate: true, ttl: nil) ⇒ Object

Save a record. Returns true if the record was persisted and false if it was invalid. This method will run the save callbacks as well as either the update or create callbacks as necessary.

Raises:

  • (ArgumentError) 


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# File 'lib/cassie/model.rb', line 439

def save(validate: true, ttl: nil)
  raise ArgumentError.new("Cannot call save on a counter table") if counter_table?
  valid_record = (validate ? valid? : true)
  if valid_record
    run_callbacks(:save) do
      if persisted?
        run_callbacks(:update) do
          self.class.connection.update(self.class.full_table_name, values_hash, key_hash, :ttl => (ttl || persistence_ttl))
        end
      else
        run_callbacks(:create) do
          self.class.connection.insert(self.class.full_table_name, attributes, :ttl => (ttl || persistence_ttl))
          @persisted = true
        end
      end
    end
    true
  else
    false
  end
end

#save! ⇒ Object

Save a record. Returns true if the record was saved and raises an ActiveRecord::RecordInvalid error if the record is invalid.



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# File 'lib/cassie/model.rb', line 463

def save!
  if save
    true
  else
    raise Cassie::RecordInvalid.new(self)
  end
end