Rails - Sep 2005 - Selecting two random rows and using the result in another controller

Hi,

Could you please help me on why this code does not work?

class Dictionary < ActiveRecord::Base
  set_table_name ''dictionary''
  set_primary_key ''word''
 
  def Dictionary.get_rnd
    ret = ''''
    find(:all, :order => ''rand()'', :limit => 2) do
|word|
      ret =+ word
    end
    return ret
  end
end

I use Dictionary.get_rnd in a controller, but it gets an empty string.

What simple thing am I missing here?

Thanks!

- Ivan V.

>   def Dictionary.get_rnd
>     ret = ''''
>     find(:all, :order => ''rand()'', :limit => 2) do
|word|
>       ret =+ word
>     end
>     return ret
>   end
> end
Just looking at your code I think you want, where word is the name of
the column in your table.
>   def Dictionary.get_rnd
>     ret = ''''
>     find(:all, :order => ''rand()'', :limit =>
2).each do |row|
>       ret += row.word + '' ''
>     end
>     return ret
>   end
> end
Of course with these same assumptions, you might prefer:
>   def Dictionary.get_rnd
>     find(:all, :order => ''rand()'', :limit => 2).map
{ |r| r.word }.join('' '')
> end
HIH
Patrick

Oh my... That''s elegant.

Thanks!

Patrick Hurley escribió:
>>  def Dictionary.get_rnd
>>    ret = ''''
>>    find(:all, :order => ''rand()'', :limit => 2)
do |word|
>>      ret =+ word
>>    end
>>    return ret
>>  end
>>end
>>    
>>
>
>Just looking at your code I think you want, where word is the name of
>the column in your table.
>
>  
>
>>  def Dictionary.get_rnd
>>    ret = ''''
>>    find(:all, :order => ''rand()'', :limit =>
2).each do |row|
>>      ret += row.word + '' ''
>>    end
>>    return ret
>>  end
>>end
>>    
>>
>
>Of course with these same assumptions, you might prefer:
>
>  
>
>>  def Dictionary.get_rnd
>>    find(:all, :order => ''rand()'', :limit =>
2).map { |r| r.word }.join('' '')
>>end
>>    
>>
>
>HIH
>Patrick
>_______________________________________________
>Rails mailing list
>Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
>http://lists.rubyonrails.org/mailman/listinfo/rails
>
>  
>

Also, would you help me with the new code?

It works, but it''s kinda ugly I think... Here it is:

class Dictionary < ActiveRecord::Base
  set_table_name ''dictionary''
  set_primary_key ''word''
 
  def self.rnd
    exists = true
    while exists == true
      short_url = find(:first, :order => "rand()").word << 
Kernel.rand(100).to_s
      check = Shortcut.find(:all, :conditions => "short_url =
''" +
short_url + "''").map {|r| r.short_url}
      if check.length == 0
        exists = false
      end
    end
    return short_url
  end
end

Basically what it does is first it retrieves a random word from the db 
and attaches a random number to it. Then it checks if there''s a row in 
another table that already has a short_url column with that value, and 
if so, generates a new random "short_url"...

I''m trying to create my own RubyURL, this way I can learn both Ruby and
Rails ;-)

Thanks a lot!

Patrick Hurley escribió:
>>  def Dictionary.get_rnd
>>    ret = ''''
>>    find(:all, :order => ''rand()'', :limit => 2)
do |word|
>>      ret =+ word
>>    end
>>    return ret
>>  end
>>end
>>    
>>
>
>Just looking at your code I think you want, where word is the name of
>the column in your table.
>
>  
>
>>  def Dictionary.get_rnd
>>    ret = ''''
>>    find(:all, :order => ''rand()'', :limit =>
2).each do |row|
>>      ret += row.word + '' ''
>>    end
>>    return ret
>>  end
>>end
>>    
>>
>
>Of course with these same assumptions, you might prefer:
>
>  
>
>>  def Dictionary.get_rnd
>>    find(:all, :order => ''rand()'', :limit =>
2).map { |r| r.word }.join('' '')
>>end
>>    
>>
>
>HIH
>Patrick
>_______________________________________________
>Rails mailing list
>Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
>http://lists.rubyonrails.org/mailman/listinfo/rails
>
>  
>

On Sep 30, 2005, at 4:04 PM, Iván Vega Rivera wrote:
> It works, but it''s kinda ugly I think... Here it is:
>
> class Dictionary < ActiveRecord::Base
>  set_table_name ''dictionary''
>  set_primary_key ''word''
>  def self.rnd
>    exists = true
>    while exists == true
>      short_url = find(:first, :order => "rand()").word
<<
> Kernel.rand(100).to_s
>      check = Shortcut.find(:all, :conditions => "short_url =
''" +
> short_url + "''").map {|r| r.short_url}
>      if check.length == 0
>        exists = false
>      end
>    end
>    return short_url
>  end
> end
>
> Basically what it does is first it retrieves a random word from the  
> db and attaches a random number to it. Then it checks if there''s a
> row in another table that already has a short_url column with that  
> value, and if so, generates a new random "short_url"...
>
> I''m trying to create my own RubyURL, this way I can learn both
Ruby
> and Rails ;-)
Ok.. here''s my stab at it..

class Dictionary < ActiveRecord::Base
   set_table_name ''dictionary''
   set_primary_key ''word''

   def self.rnd
     short_url = self.gen_short_url until self.validate_unique_url 
(short_url)
     short_url
   end

   private

   def gen_short_url
     find(:first, :order => "rand()").word <<
Kernel.rand(100).to_s
   end

   def validate_unique_url(url)
     Shortcut.count(:conditions => "short_url = ''" + url +
"''") == 0
   end
end

NOTE: I didn''t test this.  Just typed it into email.  Basic idea was  
to eliminate the unnecessary temporaries, make it slightly more  
functional, and switch to using ActiveRecord::count instead of ::find.

--Steve

Thanks Stephen, your code looks much better, although it''s not working 
yet. Rails throws a NoMethodError:

undefined method `validate_unique_url'' for Dictionary:Class

I tried some modifications, but I couldn''t get it to work... Could you 
help me out?

Regards,
Ivan V.

Stephen Waits escribió:
> Ok.. here''s my stab at it..
>
> class Dictionary < ActiveRecord::Base
>   set_table_name ''dictionary''
>   set_primary_key ''word''
>
>   def self.rnd
>     short_url = self.gen_short_url until self.validate_unique_url 
> (short_url)
>     short_url
>   end
>
>   private
>
>   def gen_short_url
>     find(:first, :order => "rand()").word <<
Kernel.rand(100).to_s
>   end
>
>   def validate_unique_url(url)
>     Shortcut.count(:conditions => "short_url = ''" +
url + "''") == 0
>   end
> end
>
> NOTE: I didn''t test this.  Just typed it into email.  Basic idea
was
> to eliminate the unnecessary temporaries, make it slightly more  
> functional, and switch to using ActiveRecord::count instead of ::find.
>
> --Steve
>
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

On 9/30/05, Iván Vega Rivera
<ivanvr-Xl95p0XkWPRBDgjK7y7TUQ@public.gmane.org>
wrote:
> Also, would you help me with the new code?
I will give it a try:

def self.rnd
  loop do
    short_url = find(:first, :order => "rand()").word <<
Kernel.rand(100).to_s
    return short_url if Shortcut.count(["short_url = ?", short_url])
== 0
  end
end
> Thanks a lot!
Not a problem

That works! Thanks!

Patrick Hurley escribió:
>On 9/30/05, Iván Vega Rivera
<ivanvr-Xl95p0XkWPRBDgjK7y7TUQ@public.gmane.org> wrote:
>  
>
>>Also, would you help me with the new code?
>>    
>>
>
>I will give it a try:
>
>def self.rnd
>  loop do
>    short_url = find(:first, :order => "rand()").word <<
Kernel.rand(100).to_s
>    return short_url if Shortcut.count(["short_url = ?",
short_url]) == 0
>  end
>end
>
>  
>
>>Thanks a lot!
>>    
>>
>Not a problem
>_______________________________________________
>Rails mailing list
>Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
>http://lists.rubyonrails.org/mailman/listinfo/rails
>
>  
>

On 10/3/05, Iván Vega Rivera
<ivanvr-Xl95p0XkWPRBDgjK7y7TUQ@public.gmane.org>
wrote:
> That works! Thanks!
Glad to help, I like smaller more elegant code :-), of course no
matter what you write, try to remember to use the built in sql quoting
when building conditions, doing it yourself will sooner or later lead
to SQL injection problems, which may ruin your whole day.

pth