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 1075
1075:       def self.from_value_pairs(pairs, op=:AND, negate=false)
1076:         pairs = pairs.map{|l,r| from_value_pair(l, r)}
1077:         pairs.map!{|ce| invert(ce)} if negate
1078:         pairs.length == 1 ? pairs.at(0) : new(op, *pairs)
1079:       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 1112
1112:       def self.invert(ce)
1113:         case ce
1114:         when BooleanExpression
1115:           case op = ce.op
1116:           when :AND, :OR
1117:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.collect{|a| BooleanExpression.invert(a)})
1118:           else
1119:             BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
1120:           end
1121:         when StringExpression, NumericExpression
1122:           raise(Sequel::Error, "cannot invert #{ce.inspect}")
1123:         when Constant
1124:           CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
1125:         else
1126:           BooleanExpression.new(:NOT, ce)
1127:         end
1128:       end

Public Instance methods

Always use an AND operator for & on BooleanExpressions

[Source]

      # File lib/sequel/sql.rb, line 1131
1131:       def &(ce)
1132:         BooleanExpression.new(:AND, self, ce)
1133:       end

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

[Source]

      # File lib/sequel/sql.rb, line 1141
1141:       def sql_boolean
1142:         self
1143:       end

Always use an OR operator for | on BooleanExpressions

[Source]

      # File lib/sequel/sql.rb, line 1136
1136:       def |(ce)
1137:         BooleanExpression.new(:OR, self, ce)
1138:       end

[Validate]