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 442
442:       def self.from_value_pairs(pairs, op=:AND, negate=false)
443:         pairs = pairs.collect do |l,r|
444:           ce = case r
445:           when Range
446:             new(:AND, new(:>=, l, r.begin), new(r.exclude_end? ? :< : :<=, l, r.end))
447:           when Array, ::Sequel::Dataset, SQLArray
448:             new(:IN, l, r)
449:           when NilClass, TrueClass, FalseClass
450:             new(:IS, l, r)
451:           when Regexp
452:             StringExpression.like(l, r)
453:           else
454:             new('=''=', l, r)
455:           end
456:           negate ? invert(ce) : ce
457:         end
458:         pairs.length == 1 ? pairs.at(0) : new(op, *pairs)
459:       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 465
465:       def self.invert(ce)
466:         case ce
467:         when BooleanExpression
468:           case op = ce.op
469:           when :AND, :OR
470:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.collect{|a| BooleanExpression.invert(a)})
471:           else
472:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
473:           end
474:         when StringExpression, NumericExpression
475:           raise(Sequel::Error, "cannot invert #{ce.inspect}")
476:         else
477:           BooleanExpression.new(:NOT, ce)
478:         end
479:       end

[Validate]