Add external data at new record creation time

Rails
#1

In my project i require a bit.ly link for each new product entered in
the database. Please guide me on how to do this?

Note: I am using a standard rails app with basic actions to test this
code

I plan on writing a helper function which will be able to take the id
for the new record and return the link.

Here are my questions:

  1. Should I add the link column in the same table as the product or
    create a new table with just a vehicle id and its corresponding bit.ly
    link?

  2. Where in the controller should i make the call to create the link as
    a product id will be required before the link can be generated and I am
    not 100% sure where exactly in the controller when creating a new record
    is the new record id available to be accessed.

Apologies in advance if the questions is not very clear but any help
will be greatly appreciated.

#2

Quee WM wrote:

I plan on writing a helper function which will be able to take the id
for the new record and return the link.

Using a “helper” function implies that the coding will trigger as the
template is being rendered. If this is the case, you don’t need an entry
in the database. Just write the helper to use the item id to look up the
item and generate the link from the item information.

However, if the link/URL is needed elsewhere (perhaps outside the Rails
app) and therefore needs to be stored in the database, then I’d suggest
you just create an extra field (bit_ly_url perhaps). This is assuming
that each vehicle has a unique URL.

As for the code that generates the URL - I’d create a custom ruby class
to do that. Put the code in the lib folder.

So for example, say you create a class CreateURL with a class method of
bit_ly_for_vehicle, you can then create a vehicle instance method to
call the CreateURL method and this can be triggered via a call back
(e.g. before_save)

So

class Vehicle < ActiveRecord::Base
before_save update_bit_ly_url

def update_bit_ly_url
bit_ly_url = CreateURL.bit_ly_for_vehicle(self.id)
end
end

#3

Rob N. wrote:

class Vehicle < ActiveRecord::Base
before_save update_bit_ly_url

def update_bit_ly_url
bit_ly_url = CreateURL.bit_ly_for_vehicle(self.id)
end
end

Actually - just spotted that you’d have to use after_save or information
other than the id to generate the url, as on create, the id doesn’t
exist until the object is saved. Also CreateUrl is probably a better
ruby class name.

#4

Thanks for the help. That put me on the right path.

#5

Back for some more help.

I added the following code to the model of the vehicle

class Vehicle < ActiveRecord::Base
after_save :update_bit_ly_url

def update_bit_ly_url
bit_ly_url = CreateUri::bit_ly_for_vehicle(self.id)
puts bit_ly_url
end
end

had to change CreateUri. to CreateUri:: as it was not recognizing
CreateUri.

maybe I have not written the class properly or have not included it in
the correct manner.

Now this is the error i get.

NameError (uninitialized constant Vehicle::CreateUri):
app/models/vehicle.rb:22:in update_bit_ly_url' app/controllers/vehicles_controller.rb:46:increate’

Any ideas?

#6

Your change from . to :: is a red herring. The method call semantics
of . and :: are the same. The error means that your CreateUri class is
not being loaded. Check the way it is loaded (by Rails autoloading, by
a require statement, etc).

Also, I would have structured the url creation class differently.
First, CreateUri is a poor class name because it is too generic.
Second, passing an integer (the vehicle id) would require the
CreateUri class to know far too much about what that integer
represents, thus coupling it conceptually to the Vehicle class. These
problems are apparent in the need for the awkward method name
“bit_ly_for_vehicle”. The Bitly url generator should accept a url and
return a url, as this is the interface provided by the service itself
(bit.ly’s API).

Given that the Bitly API requires authentication, I would prefer
something like:

Bitly.new(username, api_token).shorten(url_for(@vehicle)).short_url

“Shorten the url for the vehicle” reveals the code’s intention nicely.

In fact, and speaking of reuse, this is precisely what the Bitly gem
provides (http://github.com/philnash/bitly).

This does not address performance and reliability concerns with the
network, the Bitly service and etc., but it is at least a good start.
Also, do note that this will require url_for in your model. Google
should tell you how to make this happen.

On Jan 5, 1:29Â am, Quee WM [email protected] wrote:

 end
NameError (uninitialized constant Vehicle::CreateUri):
 app/models/vehicle.rb:22:in update_bit_ly_url'  app/controllers/vehicles_controller.rb:46:increate’

Any ideas?

Posted viahttp://www.ruby-forum.com/.

Rein H.
http://reinh.com | http://reductivelabs.com