method

order

rails latest stable - Class: ActiveRecord::QueryMethods

order(*args)

public

Applies an ORDER BY clause to a query.

#order accepts arguments in one of several formats.

symbols

The symbol represents the name of the column you want to order the results by.

User.order(:name)
# SELECT "users".* FROM "users" ORDER BY "users"."name" ASC

By default, the order is ascending. If you want descending order, you can map the column name symbol to :desc.

User.order(email: :desc)
# SELECT "users".* FROM "users" ORDER BY "users"."email" DESC

Multiple columns can be passed this way, and they will be applied in the order specified.

User.order(:name, email: :desc)
# SELECT "users".* FROM "users" ORDER BY "users"."name" ASC, "users"."email" DESC

strings

Strings are passed directly to the database, allowing you to specify simple SQL expressions.

This could be a source of SQL injection, so only strings composed of plain column names and simple function(column_name) expressions with optional ASC/DESC modifiers are allowed.

User.order('name')
# SELECT "users".* FROM "users" ORDER BY name

User.order('name DESC')
# SELECT "users".* FROM "users" ORDER BY name DESC

User.order('name DESC, email')
# SELECT "users".* FROM "users" ORDER BY name DESC, email

Arel

If you need to pass in complicated expressions that you have verified are safe for the database, you can use Arel.

User.order(Arel.sql('end_date - start_date'))
# SELECT "users".* FROM "users" ORDER BY end_date - start_date

Custom query syntax, like JSON columns for PostgreSQL, is supported in this way.

User.order(Arel.sql("payload->>'kind'"))
# SELECT "users".* FROM "users" ORDER BY payload->>'kind'

# File activerecord/lib/active_record/relation/query_methods.rb, line 595
    def order(*args)
      check_if_method_has_arguments!(__callee__, args) do
        sanitize_order_arguments(args)
      end
      spawn.order!(*args)
    end

7Notes

Reorder

stevo · Mar 27, 20127 thanks

If you want to override previously set order (even through default_scope), use reorder() instead.

E.g.

User.order('id ASC').reorder('name DESC')

would ignore ordering by id completely

Ordering on associations

rin · Oct 28, 20142 thanks

For ordering on the attribute of an associated model you have to include it:

Package.includes(:package_size).order("package_sizes.sort_order")

using hash as order

vitaly · Jan 12, 20141 thank

order can be specified as a hash, e.g.:

order(id: :desc)

This will prevent "ambiguous column" errors when the order is used with joins or includes.

Ordering on associations using merge

svegaca · Mar 11, 20161 thank

For ordering on the attribute of an associated model you can add joins to query and merge order scope: Product.joins(:category).merge(Category.order(priority: :desc))

reorder

bzsolt · Feb 12, 2015

adding to stevo's comment that reorder is also usefull when you have default scope in your model. eg: default_scope -> { order(created_at: :desc) }

arel_table order by

equivalent · Oct 5, 2015

More objected way how to achieve ORDOR BY .... DESC is like this :

class User < ActiveRecord::Base
  has_many :status_changes

  def latest_status_change
    status_changes
     .order(StatusChange.arel_table['created_at'].desc)
     .first
  end
end

class StatusChange < ActiverRecord::Base
  belongs_to :user
end

resulting in:

SELECT "status_changes".* FROM "status_changes" WHERE "status_changes"."user_id" = 1 ORDER BY "status_changes"."created_at" DESC

Benefits:

you are strictly bound to Modelclass name => renaming table in model will not break the sql code (of if it will, it will explicitly break the syntax on Ruby level, not DB level)
you still have the benefit of explicitly saying what table.column the order should be
easier to re-factor parts to Query Objects

Careful with arel column

gamov · May 19, 2016

I use what @equivalent suggests a lot but be careful, you MUST state the direction otherwise methods like take/last/first will fail silently!

StatusChange.arel_table['created_at']. asc

not:

StatusChange.arel_table['created_at']