Ruby on Rails finding last saved record

In a scenario I am finding the last saved record using the code

last = Category.find(:last)

This is to assign the id of category as the parent id to the sub-categories.

And so, I am assigning the it in this manner.

@subcategory.parent_id = last.id

This works fine, but when multiple users are tryin开发者_运维百科g to create Categories, then there is a wrong assignment of parent_id to the subcategory. (Sometimes it takes the id of a different category if that was created last.)

Is there any other way to find the last record?

Instead of doing a separate database query, you should be making changes at the same time.

If it is not possible to find the category you want by more specific means, i.e last = Category.find_by_name('category I actually want'), then update both your Category and the relevant Subcategories in the same place (your controller or model, however you've got it set up).

Try this example...it might help you:

<% Specimen.find(:all, :order => 'distribution_sheet_id DESC', :limit => 10).each do |df| %>
  <%= df.id %>
<% end %>