Rails - Apr 2006 - I need to send an email when something happens in my model...

but the model isn''t the right place to send mail from.  That just
seems like pretty bad coupling, generating emails from within the
model.  Or is that not a problem?  On top of that, these emails need
to contain links back to my site...which is a bit of a pain in
ActionMailer, but I found directions on
http://wiki.rubyonrails.com/rails/pages/HowtoUseUrlHelpersWithActionMailer
however I won''t be able to pass in an instance of the controller if
I''m generating the emails from the model.

Anyway, when a certain method is called on my model, I want to send an
email out to a bunch of users associated with that model, and have
each email contain a link back to the app.  What''s the best way to go
about doing that?

The best way to handle this is using observers.
http://rubyonrails.com/rails/classes/ActiveRecord/Observer.html

An excellent example of observers is present in Rick Olson''s
(technoweenie) act_as_authenticated plugin.

Best,

Raja



On 4/14/06, Pat Maddox <pergesu@gmail.com> wrote:
> but the model isn''t the right place to send mail from.  That just
> seems like pretty bad coupling, generating emails from within the
> model.  Or is that not a problem?  On top of that, these emails need
> to contain links back to my site...which is a bit of a pain in
> ActionMailer, but I found directions on
> http://wiki.rubyonrails.com/rails/pages/HowtoUseUrlHelpersWithActionMailer
> however I won''t be able to pass in an instance of the controller
if
> I''m generating the emails from the model.
>
> Anyway, when a certain method is called on my model, I want to send an
> email out to a bunch of users associated with that model, and have
> each email contain a link back to the app.  What''s the best way to
go
> about doing that?
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

It seems like this is only for particular AR methods (save, create,
destroy, etc).  I need to send out an email whenever a specific method
is called.

Pat



On 4/14/06, Raja Bhatia <raja.bhatia@gmail.com>
wrote:
> The best way to handle this is using observers.
> http://rubyonrails.com/rails/classes/ActiveRecord/Observer.html
>
> An excellent example of observers is present in Rick Olson''s
> (technoweenie) act_as_authenticated plugin.
>
> Best,
>
> Raja
>
>
>
> On 4/14/06, Pat Maddox <pergesu@gmail.com> wrote:
> > but the model isn''t the right place to send mail from.  That
just
> > seems like pretty bad coupling, generating emails from within the
> > model.  Or is that not a problem?  On top of that, these emails need
> > to contain links back to my site...which is a bit of a pain in
> > ActionMailer, but I found directions on
> >
http://wiki.rubyonrails.com/rails/pages/HowtoUseUrlHelpersWithActionMailer
> > however I won''t be able to pass in an instance of the
controller if
> > I''m generating the emails from the model.
> >
> > Anyway, when a certain method is called on my model, I want to send an
> > email out to a bunch of users associated with that model, and have
> > each email contain a link back to the app.  What''s the best
way to go
> > about doing that?
> > _______________________________________________
> > Rails mailing list
> > Rails@lists.rubyonrails.org
> > http://lists.rubyonrails.org/mailman/listinfo/rails
> >
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

Instiki has a relatively neat way of solving this that I''ve also  
adopted for my own code. (The Instiki version is much more extensive  
than the example that I''m going to give here.)

In the lib directory, I''ve got a class that looks like this:

   class UrlGenerator
     @@controller ||= nil

     def self.controller=(controller)
       @@controller = controller
     end

     def self.url_for(options)
       @@controller.url_for(options) if @@controller
     end
   end

Then, in a before_filter I call UrlGenerator.controller = self.

Finally, when generating email, I can call UrlGenerator.url_for(...)  
to create a URL.

Yes, this is breaking MVC in a way, but I don''t feel too bad about  
it. Giving the model the ability to generate a URL seems reasonable,  
and the URLGenerator class encapsulates that idea while hiding the  
rest of the controller.

Pete Yandell
http://9cays.com


On 15/04/2006, at 1:53 PM, Pat Maddox wrote:
> but the model isn''t the right place to send mail from.  That just
> seems like pretty bad coupling, generating emails from within the
> model.  Or is that not a problem?  On top of that, these emails need
> to contain links back to my site...which is a bit of a pain in
> ActionMailer, but I found directions on
> http://wiki.rubyonrails.com/rails/pages/ 
> HowtoUseUrlHelpersWithActionMailer
> however I won''t be able to pass in an instance of the controller
if
> I''m generating the emails from the model.
>
> Anyway, when a certain method is called on my model, I want to send an
> email out to a bunch of users associated with that model, and have
> each email contain a link back to the app.  What''s the best way to
go
> about doing that?
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails

Is the method called from the controller or the model? If its the
controller, why not wrap it with another method in the controller and call
from there?

The more sophisticated approach would just be to implement a
publish/subscribe mechanism of your own.  The simplist approach is to have
the method call something like:

def signal_event(params, sender)
    subscribers.each{|ea|
        ea.handle_event(params, sender)
}
end

This assumes that the object has a list of subscribers which include the
mail sender. For simplicity you could make params a hash and let the
subscribers read it according to the keys they need.  Normally, you''d
subclass from something that handled publish/subscribe details like
attaching and detatching subscribers, implements signal_event, etc.

You could check the Gang of Four patterns book for other implementations.
(or google for it)

cheers.

On 4/15/06, Pat Maddox <pergesu@gmail.com> wrote:
>
> It seems like this is only for particular AR methods (save, create,
> destroy, etc).  I need to send out an email whenever a specific method
> is called.
>
> Pat
>
>
>
> On 4/14/06, Raja Bhatia <raja.bhatia@gmail.com> wrote:
> > The best way to handle this is using observers.
> > http://rubyonrails.com/rails/classes/ActiveRecord/Observer.html
> >
> > An excellent example of observers is present in Rick Olson''s
> > (technoweenie) act_as_authenticated plugin.
> >
> > Best,
> >
> > Raja
> >
> >
> >
> > On 4/14/06, Pat Maddox <pergesu@gmail.com> wrote:
> > > but the model isn''t the right place to send mail from. 
That just
> > > seems like pretty bad coupling, generating emails from within the
> > > model.  Or is that not a problem?  On top of that, these emails
need
> > > to contain links back to my site...which is a bit of a pain in
> > > ActionMailer, but I found directions on
> > >
> http://wiki.rubyonrails.com/rails/pages/HowtoUseUrlHelpersWithActionMailer
> > > however I won''t be able to pass in an instance of the
controller if
> > > I''m generating the emails from the model.
> > >
> > > Anyway, when a certain method is called on my model, I want to
send an
> > > email out to a bunch of users associated with that model, and
have
> > > each email contain a link back to the app.  What''s the
best way to go
> > > about doing that?
> > > _______________________________________________
> > > Rails mailing list
> > > Rails@lists.rubyonrails.org
> > > http://lists.rubyonrails.org/mailman/listinfo/rails
> > >
> > _______________________________________________
> > Rails mailing list
> > Rails@lists.rubyonrails.org
> > http://lists.rubyonrails.org/mailman/listinfo/rails
> >
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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On Saturday 15 April 2006 08:05 am, Pete Yandell wrote:
> Instiki has a relatively neat way of solving this that I''ve also
> adopted for my own code. (The Instiki version is much more extensive
> than the example that I''m going to give here.)
>
> In the lib directory, I''ve got a class that looks like this:
>
>    class UrlGenerator
>      @@controller ||= nil
>
>      def self.controller=(controller)
>        @@controller = controller
>      end
>
>      def self.url_for(options)
>        @@controller.url_for(options) if @@controller
>      end
>    end
>
> Then, in a before_filter I call UrlGenerator.controller = self.
>
> Finally, when generating email, I can call UrlGenerator.url_for(...)
> to create a URL.
>
> Yes, this is breaking MVC in a way, but I don''t feel too bad about
> it. Giving the model the ability to generate a URL seems reasonable,
> and the URLGenerator class encapsulates that idea while hiding the
> rest of the controller.
The real problem with this, is that it you''ll have tremendous problems
if you
ever try to run in a multi-threaded  environment.  Rails may not run that way 
today, but it''s reasonable to expect that it might someday.

David

Pete Yandell wrote:
> Instiki has a relatively neat way of solving this that I''ve also
> adopted for my own code. (The Instiki version is much more extensive
> than the example that I''m going to give here.)
> 
> In the lib directory, I''ve got a class that looks like this:
> 
>    class UrlGenerator
>      @@controller ||= nil
> 
>      def self.controller=(controller)
>        @@controller = controller
>      end
> 
>      def self.url_for(options)
>        @@controller.url_for(options) if @@controller
>      end
>    end
> 
> Then, in a before_filter I call UrlGenerator.controller = self.
Unfortunately this doesn''t work when you don''t have any
controller
instances, e.g. in a daemon that works with the application data for 
maintenance, importing data from other sources and stuff like that. I 
have this problem with RForum, it''s the reason why email notifications 
don''t work for posts that are received via mailing list.

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

Here''s what I ended up doing.

I made a new model, Message, which just has two fields - the user_id
and a string which represents a message type.  In the model when the
even occurs, I create a new record.

I then created a new Mailer that has all methods and views that I need
- standard.

Finally I wrote an app which pulls all Message records from the db,
does a case to figure out what it needs to do, delivers the right
message through the mailer, and then deletes the record.

Obie Fernandez blogged about a messaging system his guys came up with,
but I couldn''t find any code for that.  When he releases it
I''ll
probably use that, and just publish messages from within my model. 
This is working fine though, so who knows, I might not have a reason
to change to a proper publish/subscribe.

Also one advantage that I realized after doing this is that no fcgi
processes are tied up with the processing of sending a bunch of
emails.  Stick it in the db, have another program that processes the
emails, and I get finer controller over how emails are delivered + my
fcgi processes stay dedicated to web stuff.

Pat


On 4/14/06, Pat Maddox <pergesu@gmail.com> wrote:
> but the model isn''t the right place to send mail from.  That just
> seems like pretty bad coupling, generating emails from within the
> model.  Or is that not a problem?  On top of that, these emails need
> to contain links back to my site...which is a bit of a pain in
> ActionMailer, but I found directions on
> http://wiki.rubyonrails.com/rails/pages/HowtoUseUrlHelpersWithActionMailer
> however I won''t be able to pass in an instance of the controller
if
> I''m generating the emails from the model.
>
> Anyway, when a certain method is called on my model, I want to send an
> email out to a bunch of users associated with that model, and have
> each email contain a link back to the app.  What''s the best way to
go
> about doing that?
>

Pat Maddox wrote:
> Also one advantage that I realized after doing this is that no fcgi
> processes are tied up with the processing of sending a bunch of
> emails.  Stick it in the db, have another program that processes the
> emails, and I get finer controller over how emails are delivered + my
> fcgi processes stay dedicated to web stuff.
How do you generate URLs in Mails?

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