Class Sequel::SQL::BooleanExpression
In: lib/sequel/sql.rb
Parent: ComplexExpression

Subclass of ComplexExpression where the expression results in a boolean value in SQL.

Methods

Included Modules

BooleanMethods

Public Class methods

Take pairs of values (e.g. a hash or array of two element arrays) and converts it to a BooleanExpression. The operator and args used depends on the case of the right (2nd) argument:

  • 0..10 - left >= 0 AND left <= 10
  • [1,2] - left IN (1,2)
  • nil - left IS NULL
  • true - left IS TRUE
  • false - left IS FALSE
  • /as/ - left ~ ‘as‘
  • :blah - left = blah
  • ‘blah’ - left = ‘blah‘

If multiple arguments are given, they are joined with the op given (AND by default, OR possible). If negate is set to true, all subexpressions are inverted before used. Therefore, the following expressions are equivalent:

  ~from_value_pairs(hash)
  from_value_pairs(hash, :OR, true)

[Source]

     # File lib/sequel/sql.rb, line 558
558:       def self.from_value_pairs(pairs, op=:AND, negate=false)
559:         pairs = pairs.collect do |l,r|
560:           ce = case r
561:           when Range
562:             new(:AND, new(:>=, l, r.begin), new(r.exclude_end? ? :< : :<=, l, r.end))
563:           when ::Array, ::Sequel::Dataset
564:             new(:IN, l, r)
565:           when NegativeBooleanConstant
566:             new("IS NOT""IS NOT", l, r.constant)
567:           when BooleanConstant
568:             new(:IS, l, r.constant)
569:           when NilClass, TrueClass, FalseClass
570:             new(:IS, l, r)
571:           when Regexp
572:             StringExpression.like(l, r)
573:           else
574:             new('=''=', l, r)
575:           end
576:           negate ? invert(ce) : ce
577:         end
578:         pairs.length == 1 ? pairs.at(0) : new(op, *pairs)
579:       end

Invert the expression, if possible. If the expression cannot be inverted, raise an error. An inverted expression should match everything that the uninverted expression did not match, and vice-versa, except for possible issues with SQL NULL (i.e. 1 == NULL is NULL and 1 != NULL is also NULL).

  BooleanExpression.invert(:a) # NOT "a"

[Source]

     # File lib/sequel/sql.rb, line 587
587:       def self.invert(ce)
588:         case ce
589:         when BooleanExpression
590:           case op = ce.op
591:           when :AND, :OR
592:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.collect{|a| BooleanExpression.invert(a)})
593:           else
594:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
595:           end
596:         when StringExpression, NumericExpression
597:           raise(Sequel::Error, "cannot invert #{ce.inspect}")
598:         else
599:           BooleanExpression.new(:NOT, ce)
600:         end
601:       end

[Validate]