Rails - Feb 2006 - How to capture the last DB insertion id ??

Hi all,

I''ve got a model - Images - and when I insert a new image into that  
db,table I would like to grab hold of the last insertion id of that  
row/record and then process it further and save reworked version back  
into the db.table again.

Example:  a new image gets inserted as a db.table.row with ID =  
12345678  (id = primary key)
The ID (12345678) is then retrieved and processed and inserted as  
''human_ref'' where it''s styled as 1234-5678 in the
same db.table.row.

Any ideas of how to do this in Rails ?  I guess I can use the  
''after_save'' callback inside the model -  Image - to do the  
processing, but how could I get hold of the last insertion id  
easily ? IF AR is currently not able to present this last insertion  
id easily, could a ''AR.last_insertion_id'' method be created
and added
to Ralls ?

Else I guess I would have to load the Image object again with a  
select sql and then retrieve the id, but that seem expensive and a  
bit complicated. I plan to insert big batches of images in this way,  
ie: 100+ images in one go, so not having to execute a bundle of  
queries repeatedly would be great from many different angles.

Any advice/guidance would be very much appreciated.


Kind regards,

Mats

----
"TextMate, coding with an incredible sense of joy and ease"
- www.macromates.com -

I am not sure if this is correct or not but i belive if you do 
Image.save the id will be automatically set so you can just use Image.id 
from then on. Though don''t quote me as i am still new to Rails also.

-- 
Posted via http://www.ruby-forum.com/.

On 26 Feb 2006, at 01:53, Rob Schultz wrote:
> I am not sure if this is correct or not but i belive if you do  
> Image.save the id will be automatically set so you can just use  
> Image.id from then on. Though don''t quote me as i am still new to
> Rails also.
Thanks Rob!

Dang, I do love Ruby & Rails!  This is all the code required to do  
what I wanted to achieve. Sometimes it''s just too easy ;-)
Although I''m sure that someone else can improve on this code even  
further.

class Image < ActiveRecord::Base

   # various validation routines and other bits

   ##  After Create method
   after_create :create_img_ref

private

   def create_img_ref
     the_id = self.id.to_s
     #  split the 8 digit id into XXXX-XXXX format with a dash
     self.img_ref = "#{the_id[0,4]}-#{the_id[4,8]}"
     #  then save it to the db record via an update
     self.update
   end

end

Hope this may help someone else someday.


Kind regards,

Mats

----
"TextMate, coding with an incredible sense of joy and ease"
- www.macromates.com -