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

from_value_pairs invert

### Included Modules

BooleanMethods

### Public Class methods

from_value_pairs(pairs, op=:AND, negate=false)

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(ce)

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]