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 1054
1054:       def self.from_value_pairs(pairs, op=:AND, negate=false)
1055:         pairs = pairs.map{|l,r| from_value_pair(l, r)}
1056:         pairs.map!{|ce| invert(ce)} if negate
1057:         pairs.length == 1 ? pairs[0] : new(op, *pairs)
1058:       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 1091
1091:       def self.invert(ce)
1092:         case ce
1093:         when BooleanExpression
1094:           case op = ce.op
1095:           when :AND, :OR
1096:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.map{|a| BooleanExpression.invert(a)})
1097:           else
1098:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
1099:           end
1100:         when StringExpression, NumericExpression
1101:           raise(Sequel::Error, "cannot invert #{ce.inspect}")
1102:         when Constant
1103:           CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
1104:         else
1105:           BooleanExpression.new(:NOT, ce)
1106:         end
1107:       end

Public Instance methods

Always use an AND operator for & on BooleanExpressions

[Source]

      # File lib/sequel/sql.rb, line 1110
1110:       def &(ce)
1111:         BooleanExpression.new(:AND, self, ce)
1112:       end

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

[Source]

      # File lib/sequel/sql.rb, line 1120
1120:       def sql_boolean
1121:         self
1122:       end

Always use an OR operator for | on BooleanExpressions

[Source]

      # File lib/sequel/sql.rb, line 1115
1115:       def |(ce)
1116:         BooleanExpression.new(:OR, self, ce)
1117:       end

[Validate]