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 1204 def initialize(conditions, default, expression=(no_expression=true; nil)) 1205 raise(Sequel::Error, 'CaseExpression conditions must be a hash or array of all two pairs') unless Sequel.condition_specifier?(conditions) 1206 @conditions = conditions.to_a.dup.freeze 1207 @default = default 1208 @expression = expression 1209 @no_expression = no_expression 1210 freeze 1211 end
Public Instance Methods
Whether to use an expression for this CASE expression.
# File lib/sequel/sql.rb 1214 def expression? 1215 !@no_expression 1216 end
Merge the CASE expression into the conditions, useful for databases that don’t support CASE expressions.
# File lib/sequel/sql.rb 1220 def with_merged_expression 1221 if expression? 1222 e = expression 1223 CaseExpression.new(conditions.map{|c, r| [::Sequel::SQL::BooleanExpression.new(:'=', e, c), r]}, default) 1224 else 1225 self 1226 end 1227 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 125 def inspect_args 126 if expression? 127 [:conditions, :default, :expression] 128 else 129 [:conditions, :default] 130 end 131 end