Class: Arel::Expression

Inherits:
Attribute show all
Defined in:
lib/arel/algebra/expression.rb

Direct Known Subclasses

Average, Count, Distinct, Maximum, Minimum, Sum

Constant Summary

Constants inherited from Attribute

Attribute::PREDICATES, Attribute::Predications

Instance Attribute Summary collapse

Attributes inherited from Attribute

#alias, #ancestor, #hash, #history, #relation

Instance Method Summary collapse

Methods inherited from Attribute

#/, #==, #christener, #column, #descends_from?, #engine, #eq, #eq_all, #eq_any, #eval, #find_correlate_in, #format, #gt, #gt_all, #gt_any, #gteq, #gteq_all, #gteq_any, #in, #in_all, #in_any, #join?, #lt, #lt_all, #lt_any, #lteq, #lteq_all, #lteq_any, #matches, #matches_all, #matches_any, #named?, #not_eq, #not_eq_all, #not_eq_any, #not_in, #not_in_all, #not_in_any, #not_matches, #not_matches_all, #not_matches_any, #original_attribute, #original_relation, #root

Methods included from Attribute::Types

#type_cast, #type_cast_to_numeric, #typecast_error

Methods included from Attribute::Orderings

#asc, #desc

Methods included from Attribute::Expressions

#average, #count, #maximum, #minimum, #sum

Constructor Details

#initialize(attribute, aliaz = nil, ancestor = nil) ⇒ Expression

Returns a new instance of Expression.



6
7
8
9
 
# File 'lib/arel/algebra/expression.rb', line 6

def initialize(attribute, aliaz = nil, ancestor = nil)
  super(attribute.relation, aliaz, :alias => aliaz, :ancestor => ancestor)
  @attribute = attribute
end

Instance Attribute Details

#attribute ⇒ Object (readonly)

Returns the value of attribute attribute.



3
4
5
 
# File 'lib/arel/algebra/expression.rb', line 3

def attribute
  @attribute
end

Instance Method Details

#aggregation? ⇒ Boolean

Returns:

  • (Boolean) 


11
12
13
 
# File 'lib/arel/algebra/expression.rb', line 11

def aggregation?
  true
end

#as(aliaz) ⇒ Object 



19
20
21
 
# File 'lib/arel/algebra/expression.rb', line 19

def as(aliaz)
  self.class.new(attribute, aliaz, self)
end

#bind(new_relation) ⇒ Object 



23
24
25
 
# File 'lib/arel/algebra/expression.rb', line 23

def bind(new_relation)
  new_relation == relation ? self : self.class.new(attribute.bind(new_relation), @alias, self)
end

#to_attribute(relation) ⇒ Object 



27
28
29
 
# File 'lib/arel/algebra/expression.rb', line 27

def to_attribute(relation)
  Attribute.new(relation, @alias, :ancestor => self)
end

#to_sql(formatter = Sql::SelectClause.new(relation)) ⇒ Object 



15
16
17
 
# File 'lib/arel/algebra/expression.rb', line 15

def to_sql(formatter = Sql::SelectClause.new(relation))
  formatter.expression self
end