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 423
423:       def self.from_value_pairs(pairs, op=:AND, negate=false)
424:         pairs = pairs.collect do |l,r|
425:           ce = case r
426:           when Range
427:             new(:AND, new(:>=, l, r.begin), new(r.exclude_end? ? :< : :<=, l, r.end))
428:           when Array, ::Sequel::Dataset, SQLArray
429:             new(:IN, l, r)
430:           when NilClass, TrueClass, FalseClass
431:             new(:IS, l, r)
432:           when Regexp
433:             StringExpression.like(l, r)
434:           else
435:             new('=''=', l, r)
436:           end
437:           negate ? invert(ce) : ce
438:         end
439:         pairs.length == 1 ? pairs.at(0) : new(op, *pairs)
440:       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 446
446:       def self.invert(ce)
447:         case ce
448:         when BooleanExpression
449:           case op = ce.op
450:           when :AND, :OR
451:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.collect{|a| BooleanExpression.invert(a)})
452:           else
453:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
454:           end
455:         when ComplexExpression
456:           raise(Sequel::Error, "operator #{ce.op} cannot be inverted")
457:         else
458:           BooleanExpression.new(:NOT, ce)
459:         end
460:       end

[Validate]