Class: Array

Inherits:
Object show all
Defined in:
lib/sequel/core_sql.rb,
lib/sequel/extensions/pg_array.rb

Overview

Sequel extends Array to add methods to implement the SQL DSL. Most of these methods require that the array not be empty and that it must consist solely of other arrays that have exactly two elements.

Direct Known Subclasses

Sequel::Postgres::PGArray, Sequel::SQL::ValueList

Instance Method Summary (collapse)

Instance Method Details

- (Boolean) all_two_pairs?

true if the array is not empty and all of its elements are arrays of size 2, false otherwise. This is used to determine if the array could be a specifier of conditions, used similarly to a hash but allowing for duplicate keys and a specific order.

[].to_a.all_two_pairs? # => false
[:a].to_a.all_two_pairs? # => false
[[:b]].to_a.all_two_pairs? # => false
[[:a, 1]].to_a.all_two_pairs? # => true

Returns:

  • (Boolean) 


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# File 'lib/sequel/core_sql.rb', line 23

def all_two_pairs?
  !empty? && all?{|i| (Array === i) && (i.length == 2)}
end

- (Object) case(*args)

Return a Sequel::SQL::CaseExpression with this array as the conditions and the given default value and expression.

[[{:a=>[2,3]}, 1]].case(0) # SQL: CASE WHEN a IN (2, 3) THEN 1 ELSE 0 END
[[:a, 1], [:b, 2]].case(:d, :c) # SQL: CASE c WHEN a THEN 1 WHEN b THEN 2 ELSE d END


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# File 'lib/sequel/core_sql.rb', line 32

def case(*args)
  ::Sequel::SQL::CaseExpression.new(self, *args)
end

- (Object) pg_array(type = nil)

Return a PGArray proxy to the receiver, using a specific database type if given. This is mostly useful as a short cut for creating PGArray objects that didn't come from the database.



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# File 'lib/sequel/extensions/pg_array.rb', line 457

def pg_array(type=nil)
  Sequel::Postgres::PGArray.new(self, type)
end

- (Object) sql_expr

Return a Sequel::SQL::BooleanExpression created from this array, matching all of the conditions. Rarely do you need to call this explicitly, as Sequel generally assumes that arrays of two element arrays specify this type of condition. One case where it can be necessary to use this is if you are using the object as a value in a filter hash and want to use the = operator instead of the IN operator (which is used by default for arrays of two element arrays).

[[:a, true]].sql_expr # SQL: a IS TRUE
[[:a, 1], [:b, [2, 3]]].sql_expr # SQL: a = 1 AND b IN (2, 3)


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# File 'lib/sequel/core_sql.rb', line 61

def sql_expr
  sql_expr_if_all_two_pairs
end

- (Object) sql_negate

Return a Sequel::SQL::BooleanExpression created from this array, matching none of the conditions.

[[:a, true]].sql_negate # SQL: a IS NOT TRUE
[[:a, 1], [:b, [2, 3]]].sql_negate # SQL: a != 1 AND b NOT IN (2, 3)


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# File 'lib/sequel/core_sql.rb', line 70

def sql_negate
  sql_expr_if_all_two_pairs(:AND, true)
end

- (Object) sql_or

Return a Sequel::SQL::BooleanExpression created from this array, matching any of the conditions.

[[:a, true]].sql_or # SQL: a IS TRUE
[[:a, 1], [:b, [2, 3]]].sql_or # SQL: a = 1 OR b IN (2, 3)


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# File 'lib/sequel/core_sql.rb', line 79

def sql_or
  sql_expr_if_all_two_pairs(:OR)
end

- (Object) sql_string_join(joiner = nil)

Return a Sequel::SQL::BooleanExpression representing an SQL string made up of the concatenation of this array's elements. If an argument is passed it is used in between each element of the array in the SQL concatenation.

[:a].sql_string_join # SQL: a
[:a, :b].sql_string_join # SQL: a || b
[:a, 'b'].sql_string_join # SQL: a || 'b'
['a', :b].sql_string_join(' ') # SQL: 'a' || ' ' || b


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# File 'lib/sequel/core_sql.rb', line 92

def sql_string_join(joiner=nil)
  if joiner
    args = zip([joiner]*length).flatten
    args.pop
  else
    args = self
  end
  args = args.collect{|a| [Symbol, ::Sequel::SQL::Expression, ::Sequel::LiteralString, TrueClass, FalseClass, NilClass].any?{|c| a.is_a?(c)} ? a : a.to_s}
  ::Sequel::SQL::StringExpression.new(:||', *args)
end

- (Object) sql_value_list Also known as: sql_array

Return a Sequel::SQL::ValueList created from this array. Used if this array contains all two element arrays and you want it treated as an SQL value list (IN predicate) instead of as a conditions specifier (similar to a hash). This is not necessary if you are using this array as a value in a filter, but may be necessary if you are using it as a value with placeholder SQL:

DB[:a].filter([:a, :b]=>[[1, 2], [3, 4]]) # SQL: (a, b) IN ((1, 2), (3, 4))
DB[:a].filter('(a, b) IN ?', [[1, 2], [3, 4]]) # SQL: (a, b) IN ((1 = 2) AND (3 = 4))
DB[:a].filter('(a, b) IN ?', [[1, 2], [3, 4]].sql_value_list) # SQL: (a, b) IN ((1, 2), (3, 4))


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# File 'lib/sequel/core_sql.rb', line 45

def sql_value_list
  ::Sequel::SQL::ValueList.new(self)
end

- (Object) ~

Return a Sequel::SQL::BooleanExpression created from this array, not matching all of the conditions.

~[[:a, true]] # SQL: a IS NOT TRUE
~[[:a, 1], [:b, [2, 3]]] # SQL: a != 1 OR b NOT IN (2, 3)


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# File 'lib/sequel/core_sql.rb', line 10

def ~
  sql_expr_if_all_two_pairs(:OR, true)
end