Class: Sequel::SQL::CaseExpression
- Inherits:
-
GenericExpression
- Object
- Expression
- GenericExpression
- Sequel::SQL::CaseExpression
- Defined in:
- lib/sequel/sql.rb,
lib/sequel/extensions/eval_inspect.rb
Overview
Represents an SQL CASE expression, used for conditional branching in SQL.
Instance Attribute Summary collapse
-
#conditions ⇒ Object
readonly
An array of all two pairs with the first element specifying the condition and the second element specifying the result if the condition matches.
-
#default ⇒ Object
readonly
The default value if no conditions match.
-
#expression ⇒ Object
readonly
The expression to test the conditions against.
Instance Method Summary collapse
-
#expression? ⇒ Boolean
Whether to use an expression for this CASE expression.
-
#initialize(conditions, default, expression = (no_expression=true; nil)) ⇒ CaseExpression
constructor
Create an object with the given conditions and default value.
-
#with_merged_expression ⇒ Object
Merge the CASE expression into the conditions, useful for databases that don’t support CASE expressions.
Methods included from Postgres::HStoreOpMethods
Methods included from Postgres::RangeOpMethods
Methods included from Postgres::ArrayOpMethods
Methods included from Postgres::JSONOpMethods
Methods included from Postgres::InetOpMethods
Methods included from Postgres::PGRowOp::ExpressionMethods
Methods included from SubscriptMethods
Methods included from StringMethods
Methods included from PatternMatchMethods
Methods included from OrderMethods
Methods included from NumericMethods
Methods included from ComplexExpressionMethods
#extract, #sql_boolean, #sql_number, #sql_string
Methods included from CastMethods
#cast, #cast_numeric, #cast_string
Methods included from BooleanMethods
Methods included from AliasMethods
Methods inherited from Expression
#==, attr_reader, #eql?, #hash, inherited, #inspect, #lit, #sql_literal
Constructor Details
#initialize(conditions, default, expression = (no_expression=true; nil)) ⇒ CaseExpression
Create an object with the given conditions and default value. An expression can be provided to test each condition against, instead of having all conditions represent their own boolean expression.
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# File 'lib/sequel/sql.rb', line 1125 def initialize(conditions, default, expression=(no_expression=true; nil)) raise(Sequel::Error, 'CaseExpression conditions must be a hash or array of all two pairs') unless Sequel.condition_specifier?(conditions) @conditions, @default, @expression, @no_expression = conditions.to_a, default, expression, no_expression end |
Instance Attribute Details
#conditions ⇒ Object (readonly)
An array of all two pairs with the first element specifying the condition and the second element specifying the result if the condition matches.
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# File 'lib/sequel/sql.rb', line 1113 def conditions @conditions end |
#default ⇒ Object (readonly)
The default value if no conditions match.
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# File 'lib/sequel/sql.rb', line 1116 def default @default end |
#expression ⇒ Object (readonly)
The expression to test the conditions against
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# File 'lib/sequel/sql.rb', line 1119 def expression @expression end |
Instance Method Details
#expression? ⇒ Boolean
Whether to use an expression for this CASE expression.
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# File 'lib/sequel/sql.rb', line 1131 def expression? !@no_expression end |
#with_merged_expression ⇒ Object
Merge the CASE expression into the conditions, useful for databases that don’t support CASE expressions.
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# File 'lib/sequel/sql.rb', line 1137 def with_merged_expression if expression? e = expression CaseExpression.new(conditions.map{|c, r| [::Sequel::SQL::BooleanExpression.new(:'=', e, c), r]}, default) else self end end |