Can the has_many create() method return an ID?

Rails
1

Hi all,

I have a has_many relationship, Cookbook :has_many Recipes

If I want to create a new recipe in my cookbook I do:

cookbook.recipes.create(data)

It would be nice if I could then easily get the id of the new recipe,
but the create() method doesn’t seem to return anything. Any ideas how?

Thanks in advance!

Cameron

2

This should work, because the create returns the object it created

cookbook.recipes.create(data).id

roland

3

I have some evidence of an id not being returned on create (from the
console):

Post.count
=> 0

Post.new.id
=> nil

Post.create.id
=> 0

Post.create.id
=> 0

Post.count
=> 2

Post.find(:all).collect { |post| post.id }
=> [1, 2]

and

@post.categories.create({:name => ‘cc1’}).id
=> 0

@post.categories.create({:name => ‘cc2’}).id
=> 0

@post.categories.size
=> 2

Are there any work arounds for this?

  • trav
4

As a work around, this should do the trick, but it requires attributes
that in combination are equivalent (or close) to the id column.
Therefore its a bit iffy.

class Post < ActiveRecord::Base

def after_create
write_attribute( ‘id’, Post.find( :first, :select => ‘id’,
:conditions => [ # attributes # ] ).id
)
end

cheers,

  • trav
5

That’s definitely not normal Rails behaviour. What version of Rails
are you running, what system, what database, etc.?

6

activerecord (1.14.2)
activesupport (1.3.1)
rails (1.1.2)
sqlite3-ruby (1.1.0)

sqlite3 -version => 3.1.3

OS-X 10.4.7

I’ve been hanging around this problem for a while now, if you want to
point me in the right direction I’ll look at the source and see if I
can do anything about it.

  • trav
7

I’m hung up on this same problem, on the same platform, save for the
fact
that I’m using rails 1.1.4 and corresponding versions of its libraries.

I took Travis’ suggestion, but extended it a bit, to make a good effort
to
insure that it returns the desired record:
#my class is called Itinerary, and uses the created_at convention,
obviously
def after_create
write_attribute( ‘id’, Itinerary.find( :first, :select => ‘id’,
:conditions => [“name = ? and created_at = ?”, self.name,
self.created_at] ).id
)
end

This works, but it’s pretty ugly, and not 100% safe: what if two users
save
an Itinerary named “Trip to Houston” within one second of each other?
;-p

David R. (doppler)

8

Wow, thanks Pete, Your awesome.

9

From the How To Use SQLite in Rails page (http://
wiki.rubyonrails.org/rails/pages/HowtoUseSQLite):

Q: It seems is that ActiveRecord?s save method doesn?t set the id
of the inserted row after saving the record to a SQLite database.
Is this an issue with SQLite or with ActiveRecord?

A: Make sure you have swig installed before installing sqlite3-
ruby! See the question immediately above this one for instructions.
I?ve had the exact problem and installing swig then re-install
sqlite3-ruby did fix it. One note: I believe sqlite3-ruby is the
preferred module (sudo gem install sqlite3-ruby).
and the relevant bit on installing swig:

On Mac OS X 10.4 Tiger, try uninstalling the gem (sudo gem
uninstall sqlite3), then use DarwinPorts or Fink to install SWIG
(sudo port install swig), making sure SWIG is in your PATH, then re-
install the SQLite3 gem (sudo gem install sqlite3).

Pete Y.

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