Class: Dynamoid::Indexes::Index

Inherits:

Object

• Object
• Dynamoid::Indexes::Index

show all

Defined in:

lib/dynamoid/indexes/index.rb

Overview

Instance Attribute Summary (collapse)

• - (Object) hash_keys

  Returns the value of attribute hash_keys.

• - (Object) name

  Returns the value of attribute name.

• - (Object) range_keys (also: #range_key?)

  Returns the value of attribute range_keys.

• - (Object) source

  Returns the value of attribute source.

Instance Method Summary (collapse)

• - (Object) delete(obj, changed_attributes = false)

  Delete an object from this index, preserving existing ids if there are any, and failing gracefully if for some reason the index doesn't already have this object in it.

• - (Index) initialize(source, name, options = {}) constructor

  Create a new index.

• - (Object) keys

  Return the array of keys this index uses for its table.

• - (Object) save(obj)

  Save an object to this index, merging it with existing ids if there's already something present at this index location.

• - (Object) sort(objs)

  Sort objects into alphabetical strings, used for composing index names correctly (since we always assume they're alphabetical).

• - (Object) table_name

  Return the table name for this index.

• - (Hash) values(attrs, changed_attributes = false)

  Given either an object or a list of attributes, generate a hash key and a range key for the index.

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# File 'lib/dynamoid/indexes/index.rb', line 16

def initialize(source, name, options = {})
  @source = source
  
  if options.delete(:range)
    @range_keys = sort(name)
  elsif options[:range_key]
    @range_keys = sort(options[:range_key])
  end
  @hash_keys = sort(name)
  @name = sort([hash_keys, range_keys])
  
  raise Dynamoid::Errors::InvalidField, 'A key specified for an index is not a field' unless keys.all?{|n| source.attributes.include?(n)}
end

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# File 'lib/dynamoid/indexes/index.rb', line 7

def hash_keys
  @hash_keys
end

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# File 'lib/dynamoid/indexes/index.rb', line 7

def name
  @name
end

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# File 'lib/dynamoid/indexes/index.rb', line 7

def range_keys
  @range_keys
end

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# File 'lib/dynamoid/indexes/index.rb', line 7

def source
  @source
end

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# File 'lib/dynamoid/indexes/index.rb', line 93

def delete(obj, changed_attributes = false)
  values = values(obj, changed_attributes)
  return true if values[:hash_value].blank? || (!values[:range_value].nil? && values[:range_value].blank?)
  existing = Dynamoid::Adapter.read(self.table_name, values[:hash_value], { :range_key => values[:range_value]})
  return true unless existing && existing[:ids] && existing[:ids].include?(obj.id)
  Dynamoid::Adapter.write(self.table_name, {:id => values[:hash_value], :ids => (existing[:ids] - Set[obj.id]), :range => values[:range_value]})
end

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# File 'lib/dynamoid/indexes/index.rb', line 43

def keys
  [Array(hash_keys) + Array(range_keys)].flatten.uniq
end

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# File 'lib/dynamoid/indexes/index.rb', line 80

def save(obj)
  self.delete(obj, true)
  values = values(obj)
  return true if values[:hash_value].blank? || (!values[:range_value].nil? && values[:range_value].blank?)
  existing = Dynamoid::Adapter.read(self.table_name, values[:hash_value], { :range_key => values[:range_value] })
  ids = ((existing and existing[:ids]) or Set.new)
  Dynamoid::Adapter.write(self.table_name, {:id => values[:hash_value], :ids => ids.merge([obj.id]), :range => values[:range_value]})
end

sort([:gamma, :alpha, :beta, :omega]) # => [:alpha, :beta, :gamma, :omega]

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# File 'lib/dynamoid/indexes/index.rb', line 36

def sort(objs)
  Array(objs).flatten.compact.uniq.collect(&:to_s).sort.collect(&:to_sym)
end

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# File 'lib/dynamoid/indexes/index.rb', line 50

def table_name
  "#{Dynamoid::Config.namespace}_index_#{source.to_s.downcase}_#{name.collect(&:to_s).collect(&:pluralize).join('_and_')}"
end

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# File 'lib/dynamoid/indexes/index.rb', line 63

def values(attrs, changed_attributes = false)
  if changed_attributes
    hash = {}
    attrs.changes.each {|k, v| hash[k.to_sym] = (v.first || v.last)}
    attrs = hash
  end
  attrs = attrs.send(:attributes) if attrs.respond_to?(:attributes)
  {}.tap do |hash|
    hash[:hash_value] = hash_keys.collect{|key| attrs[key]}.join('.')
    hash[:range_value] = range_keys.inject(0.0) {|sum, key| sum + attrs[key].to_f} if self.range_key?
  end
end