How to get last N records with activerecord?

With :limit in query, I will get first N records. What is the easiest way to get last N records?

Solution 1:

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

Solution 2:

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

Solution 3:

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

Solution 4:

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.

Solution 5:

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|