Class: Octoball::RelationProxy

Inherits:
BasicObject
Defined in:
lib/octoball/relation_proxy.rb

Constant Summary collapse

ENUM_METHODS = 
(::Enumerable.instance_methods - ::Object.instance_methods).reject do |m|
  ::ActiveRecord::Relation.instance_method(m).source_location rescue nil
end + [:each, :map, :index_by]
ENUM_WITH_BLOCK_METHODS = 
[:find, :select, :none?, :any?, :one?, :many?, :sum]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(rel, shard) ⇒ RelationProxy

Returns a new instance of RelationProxy.



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# File 'lib/octoball/relation_proxy.rb', line 7

def initialize(rel, shard)
  @rel = rel
  self.current_shard = shard
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method) ⇒ Object 



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# File 'lib/octoball/relation_proxy.rb', line 36

def method_missing(method, ...)
  # raise NoMethodError unless the method is defined in @rel
  return @rel.public_send(method, ...) unless @rel.respond_to?(method)

  preamble = <<-EOS
    def #{method}(*, **, &mblock)
      return @rel.#{method}(*, **, &mblock) unless @current_shard
  EOS
  postamble = <<-EOS
      return ret unless ret.is_a?(::ActiveRecord::Relation) || ret.is_a?(::ActiveRecord::QueryMethods::WhereChain) || ret.is_a?(::Enumerator)
      ::Octoball::RelationProxy.new(ret, @current_shard)
    end
  EOS
  connected_to = '::ActiveRecord::Base.connected_to(role: ::Octoball.current_role, shard: @current_shard)'

  if ENUM_METHODS.include?(method)
    ::Octoball::RelationProxy.class_eval <<-EOS, __FILE__, __LINE__ - 1
      #{preamble}
      ret = #{connected_to} { @rel.to_a }.#{method}(*, **, &mblock)
      #{postamble}
    EOS
  elsif ENUM_WITH_BLOCK_METHODS.include?(method)
    ::Octoball::RelationProxy.class_eval <<-EOS, __FILE__, __LINE__ - 1
      #{preamble}
      ret = nil
      if mblock
        ret = #{connected_to} { @rel.to_a }.#{method}(*, **, &mblock)
      else
        #{connected_to} { ret = @rel.#{method}(*, **, &mblock); nil } # return nil to avoid loading relation
      end
      #{postamble}
    EOS
  else
    ::Octoball::RelationProxy.class_eval <<-EOS, __FILE__, __LINE__ - 1
      #{preamble}
      ret = nil
      #{connected_to} { ret = @rel.#{method}(*, **, &mblock); nil } # return nil to avoid loading relation
      #{postamble}
    EOS
  end

  public_send(method, ...)
end

Instance Attribute Details

#current_shard ⇒ Object

Returns the value of attribute current_shard.



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# File 'lib/octoball/relation_proxy.rb', line 5

def current_shard
  @current_shard
end

Instance Method Details

#==(obj) ⇒ Object 



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# File 'lib/octoball/relation_proxy.rb', line 85

def ==(obj)
  return false if obj.respond_to?(:current_shard) && obj.current_shard != @current_shard
  return @rel == obj unless @current_shard
  ::ActiveRecord::Base.connected_to(shard: @current_shard, role: ::Octoball.current_role) { @rel == obj }
end

#===(obj) ⇒ Object 



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# File 'lib/octoball/relation_proxy.rb', line 91

def ===(obj)
  return false if obj.respond_to?(:current_shard) && obj.current_shard != @current_shard
  return @rel === obj unless @current_shard
  ::ActiveRecord::Base.connected_to(shard: @current_shard, role: ::Octoball.current_role) { @rel === obj }
end

#ar_relation ⇒ Object 



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# File 'lib/octoball/relation_proxy.rb', line 22

def ar_relation
  @rel
end

#inspect ⇒ Object 



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# File 'lib/octoball/relation_proxy.rb', line 80

def inspect
  return @rel.inspect unless @current_shard
  ::ActiveRecord::Base.connected_to(shard: @current_shard, role: ::Octoball.current_role) { @rel.inspect }
end

#respond_to?(method, include_all = false) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/octoball/relation_proxy.rb', line 26

def respond_to?(method, include_all = false)
  return true if [:ar_relation, :current_shard, :current_shard=, :using].include?(method)
  @rel.respond_to?(method, include_all)
end

#using(shard) ⇒ Object 



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# File 'lib/octoball/relation_proxy.rb', line 17

def using(shard)
  self.current_shard = shard
  self
end