alno / postgres_ext

Adds support for missing PostgreSQL data types to ActiveRecord.

PostgresExt

Adds support for missing PostgreSQL data types to ActiveRecord.

Roadmap

• Arel support for INET, CIDR and Array related where clauses
• Backport HStore code from Rails 4.0

Installation

Add this line to your application's Gemfile:

gem 'postgres_ext'

And then execute:

$ bundle

Or install it yourself as:

$ gem install postgres_ext

Usage

Just require 'postgres_ext' and use ActiveRecord as you normally would! postgres_ext extends ActiveRecord's data type handling.

• Migration/Schema.rb support
• Type Casting support
• Querying PostgreSQL datatypes

Usage Notes

Take care when dealing with arrays and other types that allow you to update their value in place. In place changes are not currently tracked in Rails (see this issue). To track changes that happen via #<< or other instance methods, be sure to call <attribute>_will_change! so that Active Record knows to persist the change.

Migration/Schema.rb support

INET

create_table :testing do |t|
  t.inet :inet_column
  # or
  t.inet :inet_column_1, :inet_column_2
  # or
  t.column :inet_column, :inet
end

CIDR

create_table :testing do |t|
  t.cidr :cidr_column
  # or
  t.cidr :cidr_column_1, :cidr_column_2
  # or
  t.column :cidr_column, :cidr
end

MACADDR

create_table :testing do |t|
  t.macaddr :macaddr_column
  # or
  t.macaddr :macaddr_column_1, :macaddr_column_2
  # or
  t.column :macaddr_column, :macaddr
end

UUID

create_table :testing do |t|
  t.uuid :uuid_column
  # or
  t.uuid :uuid_column_1, :uuid_column_2
  # or
  t.column :uuid_column, :uuid
end

Arrays

Arrays are created from any ActiveRecord supported datatype (including ones added by postgre_ext), and respect length constraints

create_table :testing do |t|
  t.integer :int_array, :array => true
  # integer[]
  t.integer :int_array, :array => true, :limit => 2
  # smallint[]
  t.string :macaddr_column_1, :array => true, :limit => 30
  # char varying(30)[]
end

Type Casting support

INET and CIDR

INET and CIDR values are converted to IPAddr objects when retrieved from the database, or set as a string.

create_table :inet_examples do |t|
  t.inet :ip_address
end

class InetExample < ActiveRecord::Base
end

inetExample = InetExample.new
inetExample.ip_address = '127.0.0.0/24'
inetExample.ip_address
# => #<IPAddr: IPv4:127.0.0.0/255.255.255.0> 
inetExample.save

inet_2 = InetExample.first
inet_2.ip_address
# => #<IPAddr: IPv4:127.0.0.0/255.255.255.0> 

Arrays

Array values can be set with Array objects. Any array stored in the database will be converted to a properly casted array of values on the way out.

create_table :people do |t|
  t.integer :favorite_numbers, :array => true
end

class Person < ActiveRecord::Base
end

person = Person.new
person.favorite_numbers = [1,2,3]
person.favorite_numbers
# => [1,2,3]
person.save

person_2 = Person.first
person_2.favorite_numbers
# => [1,2,3]
person_2.favorite_numbers.first.class
# => Fixnum

Querying PostgreSQL datatypes

• Arrays
• INET/CIDR

Arrays

• && - Array Overlap operator
• ANY or ALL functions

&& - Array Overlap operator

PostgreSQL implements the && operator, known as the overlap operator, for arrays. The overlap operator returns t (true) when two arrays have one or more elements in common.

ARRAY[1,2,3] && ARRAY[4,5,6]
-- f

ARRAY[1,2,3] && ARRAY[3,5,6]
-- t

Postgres_ext defines array_overlap, an Arel predicate for the && operator.

user_arel = User.arel_table

User.where(user_arel[:tags].array_overlap(['one','two'])).to_sql
# => SELECT \"users\".* FROM \"users\" WHERE \"users\".\"tags\" && '{one,two}'

ANY or ALL functions

When querying array columns, you have the ability to see if a predicate apply's to either any element in the array, or all elements of the array. The syntax for these predicates are slightly different then the normal where syntax in PostgreSQL. To see if an array contains the string 'test' in any location, you would write the following in SQL

SELECT *
FROM users
WHERE 'test' = ANY(users.tags)

Notice that the column is on the right hand side of the predicate, instead of the left, because we have to call the ANY function on that column.

We can generate the above query using Arel and generating the Node manually. We would use the following to accompish this:

user_arel = User.arel_table

any_tags_function = Arel::Nodes::NamedFunction.new('ANY', [user_arel[:tags]])
predicate = Arel::Nodes::Equality.new('test', any_tags_function)

User.where(predicate).to_sql
#=> SELECT \"users\".* FROM \"users\" WHERE 'test' = ANY(\"users\".\"tags\")

The ALL version of this same predicate can be generated by swap 'ANY' for 'ALL' in the named function.

INET/CIDR

<< -- Contained within operator

PostgreSQL defines the <<, or contained within operator for INET and CIDR datatypes. The << operator returns t (true) if a INET or CIDR address is contained within the given subnet.

inet '192.168.1.6' << inet '10.0.0.0/24'
-- f

inet '192.168.1.6' << inet '192.168.1.0/24'
-- t

Postgres_ext defines contained_within, an Arel predicate for the << operator.

user_arel = User.arel_table

User.where(user_arel[:ip_address].contained_witin('127.0.0.1/24')).to_sql
# => SELECT \"users\".* FROM \"users\" WHERE \"users\".\"ip_address\" << '127.0.0.1/24'

Indexes

Index types

Postgres_ext allows you to specify an index type at index creation.

add_index :table_name, :column, :index_type => :gin

Where clauses

Postgres_ext allows you to specify a where clause at index creation.

add_index :table_name, :column, :where => 'column < 50'

Authors

Dan McClain twitter github