/postgres_ext

Adds support for missing PostgreSQL data types to ActiveRecord.

Primary LanguageRubyMIT LicenseMIT

PostgresExt

Adds support for missing PostgreSQL data types to ActiveRecord.

Build Status Code Climate

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.

Usage Notes

Avoid the use of in place operators (ie Array#<<). These changes are not tracked by Rails (this issue) explains why). In place modifications also modify the default object.

Assuming we have the following model:

create_table :items do |t|
  t.string :names, :array => true, :default => []
end

class Item < ActiveRecord::Base
end

The following will modify the default value of the names attribute.

a = Item.new
a.names << 'foo'

b = Item.new
puts b.names
# => ['foo']

The supported way of modifying a.names:

a = Item.new
a.names += ['foo']

b = Item.new
puts b.names
# => []

As a result, in place operators are discouraged and will not be supported in postgres_ext at this time.

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

CITEXT

create_table :testing do |t|
  t.citext :citext_column
  # or
  t.citext :citext_column_1, :citext_column_2
  # or
  t.column :citext_column, :citext
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

&& - 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

# Execute the query
User.where(user_arel[:tags].array_overlap(['one','two']))
# => 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)

# Execute the query
User.where(predicate)
#=> 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

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

Indexes

Index types

Postgres_ext allows you to specify index type and index operator class at index creation.

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

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