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John Doe

2008-Nov-30 19:58 UTC

"You have a nil object" problem driving me crazy!

Hi!

I''ve got the following problem:

FYI:
- @dilemmas is populated in the controller via: @dilemmas Dilemma.find(:all)
- the Dilemma model has_many :dilemma_sides
- the DilemmaSide model belongs_to :dilemma
- the DilemmaSide model has_many :side_images
- the SideImage model belongs_to :dilemma_side
- side_images table has following attributes
# Table name: side_images
#
#  id              :integer(4)      not null, primary key
#  dilemma_side_id :integer(4)      not null
#  parent_id       :integer(4)
#  size            :integer(4)
#  width           :integer(4)
#  height          :integer(4)
#  content_type    :string(255)
#  filename        :string(255)
#  thumbnail       :string(255)
#  created_at      :datetime
#  updated_at      :datetime
#

Here''s the code from my view.

[code=]<% @dilemmas.each do |dilemma| %>
    <% dilemma.dilemma_sides.each do |dilemma_side| %>

      <% side_image = dilemma_side.side_images.first %>
  <%= side_image.filename.to_s  %>

    <%end%>
<% end %>[/code]
When I execute the code, I get the following error:

You have a nil object when you didn''t expect it!
The error occurred while evaluating nil.filename

If I replace the
[code=]<%= side_image.filename.to_s  %>[/code]
with
[code=]<%= side_image.filename.to_s  %>[/code]
I can confirm that the side_image has is correctly pointing to a
SideImage object:


--- !ruby/object:SideImage
attributes:
  content_type: image/jpeg
  size: "44882"
  thumbnail:
  updated_at: 2008-11-28 19:06:35
  id: "1"
  dilemma_side_id: "1"
  height: "256"
  filename: IMG_0026.JPG
  parent_id:
  width: "341"
  created_at: 2008-11-28 19:06:35
attributes_cache: {}

If on the other hand, I change the code in the following way:

[code=]<% @dilemmas.each do |dilemma| %>
    <% dilemma.dilemma_sides.each do |dilemma_side| %>
        <% dilemma_side.side_images.each do |side_image|%>
  <%= side_image.filename.to_s  %>
        <%end>
    <%end%>
<% end %>[/code]
Then it works!  But the problem with this solution is that I am looping
through all side_images associated with the dilemma_side.  I only want
to display the first image.

I have no idea why I am getting this nil object error, and I''ve tried
everything I could think of.  I am relatively new to Ruby on Rails, so
please help!

Thanks!
John
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Frederick Cheung

2008-Nov-30 20:02 UTC

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Re: "You have a nil object" problem driving me crazy!

On 30 Nov 2008, at 19:58, John Doe wrote:
>
>
> Here''s the code from my view.
>
> [code=]<% @dilemmas.each do |dilemma| %>
>    <% dilemma.dilemma_sides.each do |dilemma_side| %>
>
>      <% side_image = dilemma_side.side_images.first %>
>  <%= side_image.filename.to_s  %>
>
>    <%end%>
> <% end %>[/code]
> When I execute the code, I get the following error:
>
> You have a nil object when you didn''t expect it!
> The error occurred while evaluating nil.filename
>The obvious answer would be that you have a dilemma side with no side  
images.

Fred>
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John Doe

2008-Nov-30 20:03 UTC

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Re: "You have a nil object" problem driving me crazy!

Hi,

I''ve made a mistake in my description above.  Here''s the
corrected
version:
> If I replace the
> [code=]<%= side_image.filename.to_s  %>[/code]
> with
> [code=]<%= debug(side_image.filename)  %>[/code]
I''m desperate!  Thank you for your help!

Kind regards,
John
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John Doe

2008-Nov-30 20:07 UTC

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Re: "You have a nil object" problem driving me crazy!

Frederick Cheung wrote:
>>
> The obvious answer would be that you have a dilemma side with no side
> images.
> 
> Fred
Hi Fred,

Thank you, but as you can see above, the output of the debug command 
above, side_image does contain a Side Image:

--- !ruby/object:SideImage
attributes:
  content_type: image/jpeg
  size: "44882"
  thumbnail:
  updated_at: 2008-11-28 19:06:35
  id: "1"
  dilemma_side_id: "1"
  height: "256"
  filename: IMG_0026.JPG
  parent_id:
  width: "341"
  created_at: 2008-11-28 19:06:35
attributes_cache: {}


I''m just not able to access the attributes!

Cheers,
John
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Frederick Cheung

2008-Nov-30 20:10 UTC

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Re: "You have a nil object" problem driving me crazy!

On 30 Nov 2008, at 20:07, John Doe wrote:
>
> Frederick Cheung wrote:
>
>>>
>> The obvious answer would be that you have a dilemma side with no side
>> images.
>>
>> Fred
>
> Hi Fred,
>
> Thank you, but as you can see above, the output of the debug command
> above, side_image does contain a Side Image:
>
> --- !ruby/object:SideImage
> attributes:
>  content_type: image/jpeg
>  size: "44882"
>  thumbnail:
>  updated_at: 2008-11-28 19:06:35
>  id: "1"
>  dilemma_side_id: "1"
>  height: "256"
>  filename: IMG_0026.JPG
>  parent_id:
>  width: "341"
>  created_at: 2008-11-28 19:06:35
> attributes_cache: {}
>
>
> I''m just not able to access the attributes!
>
> Cheers,
> John
> --  
> Posted via http://www.ruby-forum.com/.
>
> >

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Frederick Cheung

2008-Nov-30 20:12 UTC

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Re: "You have a nil object" problem driving me crazy!

On 30 Nov 2008, at 20:07, John Doe wrote:
>
> Frederick Cheung wrote:
>
>>>
>> The obvious answer would be that you have a dilemma side with no side
>> images.
>>
>> Fred
>
> Hi Fred,
>
> Thank you, but as you can see above, the output of the debug command
> above, side_image does contain a Side Image:
>Are you sure that''s not displaying the side image from a previous  
iteration through the loop ?

How about you change your code to

<% @dilemmas.each do |dilemma| %>
    <% dilemma.dilemma_sides.each do |dilemma_side| %>

      <% side_image = dilemma_side.side_images.first %>
      <% if !side_image %>
        Side <%= dilemma_side.id %> has no images
      <% end %>
    <%end%>
<% end %>

and see what it outputs.

Fred
> --- !ruby/object:SideImage
> attributes:
>  content_type: image/jpeg
>  size: "44882"
>  thumbnail:
>  updated_at: 2008-11-28 19:06:35
>  id: "1"
>  dilemma_side_id: "1"
>  height: "256"
>  filename: IMG_0026.JPG
>  parent_id:
>  width: "341"
>  created_at: 2008-11-28 19:06:35
> attributes_cache: {}
>
>
> I''m just not able to access the attributes!
>
> Cheers,
> John
> -- 
> Posted via http://www.ruby-forum.com/.
>
> >

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John Doe

2008-Nov-30 20:14 UTC

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Re: "You have a nil object" problem driving me crazy!

Damn, again made a mistake in my description:
>> [code=]<%= side_image.filename.to_s  %>[/code]
> 
>> with
> 
>> [code=]<%= debug(side_image)  %>[/code]
> 

That''s it guys, that''s the correct version.  Sorry for the
confusion!
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John Doe

2008-Nov-30 20:22 UTC

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Re: "You have a nil object" problem driving me crazy!

> How about you change your code to
> 
> <% @dilemmas.each do |dilemma| %>
>     <% dilemma.dilemma_sides.each do |dilemma_side| %>
> 
>       <% side_image = dilemma_side.side_images.first %>
>       <% if !side_image %>
>         Side <%= dilemma_side.id %> has no images
>       <% end %>
>     <%end%>
> <% end %>
> 
> and see what it outputs.
> 
> Fred
Hey,

I''ve tried it, and as expected, it does not go into the loop.  I am
sure
that it is finding the Side Image belonging to the Dilemma Side.  For 
some strange reason, when I loop through the array which contains the 
Side Images:

 <% dilemma_side.side_images.each do |side_image|%>
  <%= side_image.filename.to_s  %>
        <%end>

Then Rails allows me to access the attribute directly.  I''m certainly 
doing something wrong with instance variables assignments/declarations.
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David A. Black

2008-Nov-30 20:28 UTC

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Re: "You have a nil object" problem driving me crazy!

Hi --

On Sun, 30 Nov 2008, John Doe wrote:
>
>
>> How about you change your code to
>>
>> <% @dilemmas.each do |dilemma| %>
>>     <% dilemma.dilemma_sides.each do |dilemma_side| %>
>>
>>       <% side_image = dilemma_side.side_images.first %>
>>       <% if !side_image %>
>>         Side <%= dilemma_side.id %> has no images
>>       <% end %>
>>     <%end%>
>> <% end %>
>>
>> and see what it outputs.
>>
>> Fred
>
> Hey,
>
> I''ve tried it, and as expected, it does not go into the loop.  I
am sure
> that it is finding the Side Image belonging to the Dilemma Side.  For
> some strange reason, when I loop through the array which contains the
> Side Images:
>
> <% dilemma_side.side_images.each do |side_image|%>
>  <%= side_image.filename.to_s  %>
>        <%end>
>
> Then Rails allows me to access the attribute directly.  I''m
certainly
> doing something wrong with instance variables assignments/declarations.
Is the code you''re showing us cut-and-pasted from your views? It looks
like it might be a typo (like @side_image for side_image), so to rule
that out I wanted to be sure this is the actual template code.


David

-- 
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INTRO TO RAILS (Jan 12-15), Fort Lauderdale, FL
See http://www.rubypal.com for details
Coming in 2009: The Well-Grounded Rubyist (http://manning.com/black2)

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John Doe

2008-Nov-30 20:49 UTC

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Re: "You have a nil object" problem driving me crazy!

> Is the code you''re showing us cut-and-pasted from your views? It
looks
> like it might be a typo (like @side_image for side_image), so to rule
> that out I wanted to be sure this is the actual template code.
Hi David,

Yes, it is an actual copy an paste.

Thanks!
John
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Bobnation

2008-Nov-30 21:18 UTC

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Re: "You have a nil object" problem driving me crazy!

Could you maybe copy and paste it into pastie so that it is easier for
everyone to look at?

On Nov 30, 2:49 pm, John Doe
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:> > Is the code you''re showing us cut-and-pasted from your views?
It looks
> > like it might be a typo (like @side_image for side_image), so to rule
> > that out I wanted to be sure this is the actual template code.
>
> Hi David,
>
> Yes, it is an actual copy an paste.
>
> Thanks!
> John
> --
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John Doe

2008-Nov-30 21:35 UTC

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"You have a nil object" problem driving me crazy! [SOLVED]

Guys,

The issue is solved.  I dropped and repopulated my database, and it now 
works.  I guess Fred was right after all, I was probably having a Side 
without an Image in one of my loops.

Thanks for your time! I appreciate it.

Kind regards,
John





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Rails - Nov 2008 - "You have a nil object" problem driving me crazy!

"You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

Re: "You have a nil object" problem driving me crazy!

"You have a nil object" problem driving me crazy! [SOLVED]