Rails - Nov 2006 - simple thing about an undefined method throwing me

Hey there,
i am having some trouble with a method in a model ( i am new to rails
and ruby ) comming from python

so anyway, here is what i have in my Site.rb model:

class Site < ActiveRecord::Base
    belongs_to :group
    belongs_to :status_sensor
    has_many :site_options


    def has_pressure_sensor
        y_n = ''n''
        self.sites.each do |site|
            if site.option = ''pressure''
                y_n = ''y''
            end
        end
    end

end

and in my view:
<table>
    <th>site</th>
    <th>current status</th>

    <% @group.sites.each do |site|  %>
    <tr>
        <td><%= site.site_name %></td>
        <td>
            <%= site.status_sensor.page_value %>
            <img
src="<%fetch_circle_for(site.status_sensor.page_value)%>" %>
        </td>
        <td>
            <%= site.has_pressure_sensor %>
        </td>
    </tr>

<% end %>

this is what i get:

undefined method `has_pressure_sensor'' for #<Site:0xb750e6ac>

i just want it to print out a y or n for yes or no

if you have read this far, thank you for your time.
shawn


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> Hey there,
> i am having some trouble with a method in a model ( i am new to rails
> and ruby ) comming from python
>
> so anyway, here is what i have in my Site.rb model:
>
> class Site < ActiveRecord::Base
>    belongs_to :group
>    belongs_to :status_sensor
>    has_many :site_options
>
>
>    def has_pressure_sensor
>        y_n = ''n''
>        self.sites.each do |site|
>            if site.option = ''pressure''
>                y_n = ''y''
>            end
>        end
>    end
Hrm... I don''t know the rest of your models, but guessing I think your 
method should look more like this if only because your calling 
''self.sites'' which according to your model above a site
doesn''t have
sites...

def has_pressure_sensor?
   self.site_options.each do |option|
     return true if option == ''pressure''
   end
   false
end

That will return true if one of the site_options for that site equals 
''pressure'' otherwise false.  The ''?'' in the
name is a ruby convetion when
you''re querying truth/false-ness.

Then in your view you could do:

<%= site.has_pressure_sensor? ? ''yes'' :
''no'' %>

As for why it''s not being seen, perhaps you are running in production 
mode?  Or for some other reason need to restart your rails app.

-philip

>
> end
>
> and in my view:
> <table>
>    <th>site</th>
>    <th>current status</th>
>
>    <% @group.sites.each do |site|  %>
>    <tr>
>        <td><%= site.site_name %></td>
>        <td>
>            <%= site.status_sensor.page_value %>
>            <img src="<%>
fetch_circle_for(site.status_sensor.page_value)%>" %>
>        </td>
>        <td>
>            <%= site.has_pressure_sensor %>
>        </td>
>    </tr>
>
> <% end %>
>
> this is what i get:
>
> undefined method `has_pressure_sensor'' for
#<Site:0xb750e6ac>
>
> i just want it to print out a y or n for yes or no
>
> if you have read this far, thank you for your time.
> shawn
>
>
> >
>
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cool, thanks very much
sk


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woops, it isn''t working right.

it is printing no on all , even the ones that should print yes.

in my SiteOption model i have belongs_to :site
and in Sites.rb model i have
has_many :site_options

i have checked the options for the ones i am listing and two of the 6
have the option of pressure in the site_options table.

anything else i may have left out ?

sk


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Hey,

comments below:

On 16-Nov-06, at 11:37 AM, nephish wrote:
>
> woops, it isn''t working right.
>
> it is printing no on all , even the ones that should print yes.
>
> in my SiteOption model i have belongs_to :site
> and in Sites.rb model i have
> has_many :site_options
>
> i have checked the options for the ones i am listing and two of the 6
> have the option of pressure in the site_options table.
>
> anything else i may have left out ?
>
I assume that you''re using the code for has_pressure_sensor that Phil  
Hallstrom put in his email - right?

def has_pressure_sensor?
    self.site_options.each do |option|
      return true if option == ''pressure''
    end
    false
end

Looking at that (and your has_many :site_options) then of *course* it  
always returns false.

return true if option == ''pressure''

Except the option isn''t a String, it''s a SiteOption so the
comparison
is always false.

You haven''t said what the members of site_option are but I''ll
take a
guess and say you want something
more like this:

def has_pressure_sensor?
   self.site_options.any? {|option| option.name == ''pressure''}
end

HTH,
Trevor
> sk
>
>
> 
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yep, that worked.
thanks so much !

sk


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