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 arrays of two pairs) 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
  • /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 446
446:       def self.from_value_pairs(pairs, op=:AND, negate=false)
447:         pairs = pairs.collect do |l,r|
448:           ce = case r
449:           when Range
450:             new(:AND, new(:>=, l, r.begin), new(r.exclude_end? ? :< : :<=, l, r.end))
451:           when Array, ::Sequel::Dataset, SQLArray
452:             new(:IN, l, r)
453:           when NilClass, TrueClass, FalseClass
454:             new(:IS, l, r)
455:           when Regexp
456:             StringExpression.like(l, r)
457:           else
458:             new('=''=', l, r)
459:           end
460:           negate ? invert(ce) : ce
461:         end
462:         pairs.length == 1 ? pairs.at(0) : new(op, *pairs)
463:       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).

[Source]

     # File lib/sequel/sql.rb, line 469
469:       def self.invert(ce)
470:         case ce
471:         when BooleanExpression
472:           case op = ce.op
473:           when :AND, :OR
474:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.collect{|a| BooleanExpression.invert(a)})
475:           else
476:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
477:           end
478:         when ComplexExpression
479:           raise(Sequel::Error, "operator #{ce.op} cannot be inverted")
480:         else
481:           BooleanExpression.new(:NOT, ce)
482:         end
483:       end

[Validate]