On Jan 24, 2008, at 1:34 AM, zetetic wrote:
> On Jan 23, 10:02 pm, laredotornado <laredotorn... / zipmail.com> wrote:
>> Hi,
>>
>> I have several fields on my page, distinguished by numbers in the id:
>>
>> <% for i in 1 .. 5 %>
>>   <tr><td>
>>       <table>
>>         <tr>
>>           <td><%= text_field_tag("prescription_number" + i.to_s,  
>> "") %></td>
>>           <td><%= text_field_tag("description" + i.to_s, "") %></td>
>>         </tr>
>>         <tr>
>>           <td align="center">Prescription Number</td>
>>           <td align="center">Description</td>
>>         </tr>
>>       </table>
>>     </td></tr>
>> <% end %>
>>
>> However, when I try and access the values in my controller,
>>
>>                i = 0
>>                while params[:prescription_number + i.to_s] != nil and
>> params[:description + i.to_s] != nil        # line 7
>>                        session[:prescription_number + i.to_s] =
>> params[:prescription_number + i.to_s]
>>                        session[:description + i.to_s] =
>> params[:description + i.to_s]
>>                        i += 1
>>                end
>>
>> I get the error
>>
>> NoMethodError in OrderController#confirm
>> undefined method `+' for :prescription_number:Symbol
>> RAILS_ROOT: ./script/../config/..
>> Application Trace | Framework Trace | Full Trace
>> /usr/local/apache2/htdocs/easyrx/app/controllers/order_controller.rb:
>> 7:in `confirm'
>>
>> What is the correct way to access my parameter values?
>>
>> Thanks, - Dave
>
> You're trying to concatenate a Symbol with a string. This IRB session
> should help explain the difference:
>
> irb(main):019:0> "Hello".class
> => String
> irb(main):020:0> "Hello".intern
> => :Hello
> irb(main):021:0> :Hello.class
> => Symbol
> irb(main):022:0> :Hello + " World"
> NoMethodError: undefined method `+' for :Hello:Symbol
>        from (irb):22
> irb(main):023:0> :Hello.to_s + " World"
> => "Hello World"

While that is a valid explanation of the error, the real problem is  
better solved with:

<% for i in 1 .. 5 %>
   <tr><td>
       <table>
         <tr>
           <td><%= text_field_tag("prescription_number[]", "") %></td>
           <td><%= text_field_tag("description[], "") %></td>
         </tr>
         <tr>
           <td align="center">Prescription Number</td>
           <td align="center">Description</td>
         </tr>
       </table>
     </td></tr>
<% end %>

Note the addition of the "[]" at the end of the name.  If you need to  
have an id on these, too, then add an :id=>"my_id" to the  
text_field_tag.

Then you get back the parameter values in an Array and in the  
controller can do something like:

   params[:prescription_number].each_with_index do | 
prescription_number, i|
     break if prescription_number.blank? || params[:description] 
[i].blank?
     (session[:prescription_number] ||= [])[i] = prescription_number
     (session[:description] ||= [])[i] = params[:description][i]
   end

The '||= []' part is to initialize the value of the session hash to be  
an empty Array if it starts nil.

Having said this, I'd recommend that you consider creating a model to  
hold this data and then you just have one object to store in the  
session (if you really have to do that, of course).  This model does  
not have to be backed by ActiveRecord. (Note that I'm going out on a  
limb assuming that you're using Rails even though you've asked in the  
Ruby list ;-)

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob / AgileConsultingLLC.com