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How to get last N records with activerecord?

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Can you use ActiveRecord without rails?

One of the primary aspects of ActiveRecord is that there is very little to no configuration needed. It follow convention over configuration. ActiveRecord is commonly used with the Ruby-on-Rails framework but you can use it with Sinatra or without any web framework if desired.

Is ActiveRecord an ORM?

ActiveRecord is an ORM. It's a layer of Ruby code that runs between your database and your logic code. When you need to make changes to the database, you'll write Ruby code, and then run "migrations" which makes the actual changes to the database.

What does ActiveRecord base do?

ActiveRecord::Base indicates that the ActiveRecord class or module has a static inner class called Base that you're extending.

What is ActiveRecord naming convention?

Active Record uses naming conventions for the columns in database tables, depending on the purpose of these columns. Foreign keys - These fields should be named following the pattern singularized_table_name_id (e.g., item_id , order_id ).


This is the Rails 3 way

SomeModel.last(5) # last 5 records in ascending order

SomeModel.last(5).reverse # last 5 records in descending order

Updated Answer (2020)

You can get last N records simply by using last method:

Record.last(N)

Example:

User.last(5)

Returns 5 users in descending order by their id.

Deprecated (Old Answer)

An active record query like this I think would get you what you want ('Something' is the model name):

Something.find(:all, :order => "id desc", :limit => 5).reverse

edit: As noted in the comments, another way:

result = Something.find(:all, :order => "id desc", :limit => 5)

while !result.empty?
        puts result.pop
end

new way to do it in rails 3.1 is SomeModel.limit(5).order('id desc')


For Rails 5 (and likely Rails 4)

Bad:

Something.last(5)

because:

Something.last(5).class
=> Array

so:

Something.last(50000).count

will likely blow up your memory or take forever.

Good approach:

Something.limit(5).order('id desc')

because:

Something.limit(5).order('id desc').class
=> Image::ActiveRecord_Relation

Something.limit(5).order('id desc').to_sql
=> "SELECT  \"somethings\".* FROM \"somethings\" ORDER BY id desc LIMIT 5"

The latter is an unevaluated scope. You can chain it, or convert it to an array via .to_a. So:

Something.limit(50000).order('id desc').count

... takes a second.


For Rails 4 and above version:

You can try something like this If you want first oldest entry

YourModel.order(id: :asc).limit(5).each do |d|

You can try something like this if you want last latest entries..

YourModel.order(id: :desc).limit(5).each do |d|