Rails - Jan 2010 - ActiveRecord method creation issue

Sorry in advance if this is on the wrong forum/topic.

I''m a novice ruby developer, starting to use ActiveRecord, and am
getting stuck with the following problem:

I have a class defined:

class User < ActiveRecord::Base
  set_table_name "users"
  has_one :locations
  has_one :sessions
  has_many :task_postings
  has_many :task_descriptions


  def get_messages(uid)
    user = User.find(:first, :conditions => [ "id =
''#{uid}''" ])
    if(user) then
      return user.messages_waiting
    end
    return nil
  end
end

In order to call the method, I have to create an instance of the class
and refer to the method:

new_user = User.new
new_user.get_messages(1)

If I call the method by referring to the class, User.get_messages, I get
a non-existent method error. What I wanted is to be able to call the
class as follows:

User.get_messages(1)

in order to do that, I re-defined the class as:

def self.get_messages(uid)

which works for the call, now I get an exception: "uninitialized
constant MysqlCompat::MysqlRes", which implies to me that the
"singleton" version of the method call is not seeing the already open
and functional ActiveRecord mysql class.

Can anyone shed some light on this?

Thanks VERY much,
Gal Bar-or, Wyoming USA
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Gal Bar-or wrote:
> Sorry in advance if this is on the wrong forum/topic.
> 
> I''m a novice ruby developer, starting to use ActiveRecord, and am
> getting stuck with the following problem:
> 
> I have a class defined:
> 
> class User < ActiveRecord::Base
>   set_table_name "users"
>   has_one :locations
>   has_one :sessions
>   has_many :task_postings
>   has_many :task_descriptions
> 
> 
>   def get_messages(uid)
>     user = User.find(:first, :conditions => [ "id =
''#{uid}''" ])
>     if(user) then
>       return user.messages_waiting
>     end
>     return nil
>   end
> end
> 
> In order to call the method, I have to create an instance of the class
> and refer to the method:
> 
> new_user = User.new
> new_user.get_messages(1)
> 
> If I call the method by referring to the class, User.get_messages, I get
> a non-existent method error. What I wanted is to be able to call the
> class as follows:
> 
> User.get_messages(1)
> 
> in order to do that, I re-defined the class as:
> 
> def self.get_messages(uid)
No, actually you don''t want to do this.  get_messages is conceptually a
property of an individual user, not of the User class.

You also don''t need uid as an argument, since the User object
you''re
calling this on already knows its id.  The proper way to do this would 
be

def get_messages # note: no arguments
  self.messages_waiting
end

Finally, get_* is somewhat unidiomatic in Ruby; this method should 
perhaps just be called messages.

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org
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