class Sequel::SQL::CaseExpression
Represents an SQL
CASE expression, used for conditional branching in SQL
.
Attributes
An array of all two pairs with the first element specifying the condition and the second element specifying the result if the condition matches.
The default value if no conditions match.
An optional expression to test the conditions against
Public Class Methods
Create an object with the given conditions and default value, and optional expression. An expression can be provided to test each condition against, instead of having all conditions represent their own boolean expression.
# File lib/sequel/sql.rb 1202 def initialize(conditions, default, expression=(no_expression=true; nil)) 1203 raise(Sequel::Error, 'CaseExpression conditions must be a hash or array of all two pairs') unless Sequel.condition_specifier?(conditions) 1204 @conditions = conditions.to_a.dup.freeze 1205 @default = default 1206 @expression = expression 1207 @no_expression = no_expression 1208 freeze 1209 end
Public Instance Methods
Whether to use an expression for this CASE expression.
# File lib/sequel/sql.rb 1212 def expression? 1213 !@no_expression 1214 end
Merge the CASE expression into the conditions, useful for databases that don't support CASE expressions.
# File lib/sequel/sql.rb 1218 def with_merged_expression 1219 if expression? 1220 e = expression 1221 CaseExpression.new(conditions.map{|c, r| [::Sequel::SQL::BooleanExpression.new(:'=', e, c), r]}, default) 1222 else 1223 self 1224 end 1225 end
Private Instance Methods
CaseExpression's initializer checks whether an argument was provided, to differentiate CASE WHEN from CASE NULL WHEN, so check if an expression was provided, and only include the expression in the inspect output if so.
# File lib/sequel/extensions/eval_inspect.rb 123 def inspect_args 124 if expression? 125 [:conditions, :default, :expression] 126 else 127 [:conditions, :default] 128 end 129 end