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   sql_boolean   |  

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 912
912:       def self.from_value_pairs(pairs, op=:AND, negate=false)
913:         pairs = pairs.collect do |l,r|
914:           ce = case r
915:           when Range
916:             new(:AND, new(:>=, l, r.begin), new(r.exclude_end? ? :< : :<=, l, r.end))
917:           when ::Array, ::Sequel::Dataset
918:             new(:IN, l, r)
919:           when NegativeBooleanConstant
920:             new("IS NOT""IS NOT", l, r.constant)
921:           when BooleanConstant
922:             new(:IS, l, r.constant)
923:           when NilClass, TrueClass, FalseClass
924:             new(:IS, l, r)
925:           when Regexp
926:             StringExpression.like(l, r)
927:           else
928:             new('=''=', l, r)
929:           end
930:           negate ? invert(ce) : ce
931:         end
932:         pairs.length == 1 ? pairs.at(0) : new(op, *pairs)
933:       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 941
941:       def self.invert(ce)
942:         case ce
943:         when BooleanExpression
944:           case op = ce.op
945:           when :AND, :OR
946:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.collect{|a| BooleanExpression.invert(a)})
947:           else
948:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
949:           end
950:         when StringExpression, NumericExpression
951:           raise(Sequel::Error, "cannot invert #{ce.inspect}")
952:         when Constant
953:           CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
954:         else
955:           BooleanExpression.new(:NOT, ce)
956:         end
957:       end

Public Instance methods

Always use an AND operator for & on BooleanExpressions

[Source]

     # File lib/sequel/sql.rb, line 960
960:       def &(ce)
961:         BooleanExpression.new(:AND, self, ce)
962:       end

Return self instead of creating a new object to save on memory.

[Source]

     # File lib/sequel/sql.rb, line 970
970:       def sql_boolean
971:         self
972:       end

Always use an OR operator for | on BooleanExpressions

[Source]

     # File lib/sequel/sql.rb, line 965
965:       def |(ce)
966:         BooleanExpression.new(:OR, self, ce)
967:       end

[Validate]