Subclass of ComplexExpression
where the expression results in a boolean value in SQL
.
Included modules
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 |
|
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)
# File lib/sequel/sql.rb 1081 def self.from_value_pairs(pairs, op=:AND, negate=false) 1082 pairs = pairs.map{|l,r| from_value_pair(l, r)} 1083 pairs.map!{|ce| invert(ce)} if negate 1084 pairs.length == 1 ? pairs[0] : new(op, *pairs) 1085 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"
# File lib/sequel/sql.rb 1140 def self.invert(ce) 1141 case ce 1142 when BooleanExpression 1143 case op = ce.op 1144 when :AND, :OR 1145 BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.map{|a| BooleanExpression.invert(a)}) 1146 when :IN, :"NOT IN" 1147 BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup) 1148 else 1149 if ce.args.length == 2 1150 case ce.args[1] 1151 when Function, LiteralString, PlaceholderLiteralString 1152 # Special behavior to not push down inversion in this case because doing so 1153 # can result in incorrect behavior for ANY/SOME/ALL operators. 1154 BooleanExpression.new(:NOT, ce) 1155 else 1156 BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup) 1157 end 1158 else 1159 BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup) 1160 end 1161 end 1162 when StringExpression, NumericExpression 1163 raise(Sequel::Error, "cannot invert #{ce.inspect}") 1164 when Constant 1165 CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}") 1166 else 1167 BooleanExpression.new(:NOT, ce) 1168 end 1169 end
Public Instance methods
Always use an AND operator for & on BooleanExpressions
# File lib/sequel/sql.rb 1172 def &(ce) 1173 BooleanExpression.new(:AND, self, ce) 1174 end
Return self instead of creating a new object to save on memory.
# File lib/sequel/sql.rb 1182 def sql_boolean 1183 self 1184 end
Always use an OR operator for | on BooleanExpressions
# File lib/sequel/sql.rb 1177 def |(ce) 1178 BooleanExpression.new(:OR, self, ce) 1179 end