# File\_column

**URL:** <https://www.ruby-forum.com/t/file-column/91786>\
**Category:** Rails\
**Created:** [December 1, 2005, 10:35pm UTC](https://www.ruby-forum.com/t/file-column/91786 "2005-12-01T22:35:23Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![scidept](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@scidept](https://www.ruby-forum.com/u/scidept)\
**Post date:** [December 1, 2005, 10:35pm UTC](https://www.ruby-forum.com/t/file-column/91786/1 "2005-12-01T22:35:23Z")

</div>

I’m trying to use the file\_column plugin, and the upload portion of it  
works  
beautifully.  
I’m trying to display the images now and I’m having a couple problems.  
First is, when I try to use url\_for\_file\_column, I get the following  
error:  
You have a nil object when you didn’t expect it!  
The error occured while evaluating nil.image\_relative\_path

The Code I’m using is this:  
\<% for photo in @photos %\>

```
<td><%= image_tag url_for_file_column("photo", "image") %></td>

<td><%=h item.name %></td>

<td><%=h item.description %></td>

<td><%= link_to 'Show', :action => 'show', :id => item %></td>

<td><%= link_to 'Edit', :action => 'edit', :id => item %></td>

<td><%= link_to 'Destroy', { :action => 'destroy', :id => item },

```

:confirm =\> ‘Are you sure?’ %\>

\<% end %\>

Second, I don’t know how to specify which version of the photo I  
uploaded to  
use.  
I have a “thumb” and a “medium” and then the native size uploaded. How  
do I  
differentiate between the two?

Any help is appreciated,  
Thanks,  
BJ Clark

---

<div class="post-metadata">

**Author:** ![scidept](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@scidept](https://www.ruby-forum.com/u/scidept)\
**Post date:** [December 1, 2005, 10:43pm UTC](https://www.ruby-forum.com/t/file-column/91786/2 "2005-12-01T22:43:29Z")

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Hi !

2005/12/1, BJ Clark [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> I’m trying to display the images now and I’m having a couple problems.  
> First is, when I try to use url\_for\_file\_column, I get the following error:  
> You have a nil object when you didn’t expect it!  
> The error occured while evaluating nil.image\_relative\_path

This is because you need to have an instance variable and not a local  
one:  
\<% for @photo in @photos %\>  
…  
\<% end %\>

> Second, I don’t know how to specify which version of the photo I uploaded to  
> use.  
> I have a “thumb” and a “medium” and then the native size uploaded. How do I  
> differentiate between the two?

url\_for\_file\_column has a third parameter - version. If you leave it  
off, you’ll get the original size, else you’ll get that named version.

Hope that helps !

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<div class="post-metadata">

**Author:** ![scidept](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@scidept](https://www.ruby-forum.com/u/scidept)\
**Post date:** [December 1, 2005, 11:28pm UTC](https://www.ruby-forum.com/t/file-column/91786/3 "2005-12-01T23:28:06Z")

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Works beautifully!  
Thanks,  
BJ Clark

---

<div class="post-metadata">

**Author:** ![scidept](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@scidept](https://www.ruby-forum.com/u/scidept)\
**Post date:** [September 25, 2007, 11:05pm UTC](https://www.ruby-forum.com/t/file-column/91786/4 "2007-09-25T23:05:29Z")

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On 6/29/07, Yann KLIS [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> Juste pour info, attachment\_fu est le successeur de acts\_as\_attachment.  
> Quant à file\_column, le plugin est un peu mort (pas de mise à jour depuis  
> 2005), la commande d’install sur la page web ne fonctionne pas (la dernière  
> fois que j’avais essayé en tout cas, ce qui remonte à quelques mois  
> maintenant), etc.

Je suis d’accord avec Yann, de plus attachment\_fu est beaucoup plus  
modulaire, et propose des hooks partout ou on en a besoin (before  
thumbnail,  
before\_resize …), supporte les fichiers en DB, ou sur S3 et pas  
seulement  
les fichiers plats, offre la possibilité de resizer les images avec  
imageMagick ou image Science, … C’est un des rares plugin que je n’ai  
pas  
eu une folle envie de patcher pour le faire rentrer dans mes besoins.  
Les  
tests sont très bien fait et Rick a rajouté d’excellent helper pour  
faciliter le tout.

Son seul défaut à mon avis, il est totalement concu pour stocker les  
fichiers à uploader, c’est à dire que les fonctions acceptent comme  
argument  
des UploadedFile facon CGI. Résultat pour utiliser le plugin afin de  
stocker  
ou par exemple peupler sa base de donnée il faut faire du duck typing  
pour  
fournir un Object qui ressemble à ce qu’il attend. Ce qui est un peu  
chiant  
quand on stocke sur S3 ou en DB mais ne pose pas de problème quand ce  
sont  
des fichiers plats car rails a tout ce qu’il faut.

Renaud

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<div class="post-metadata">

**Author:** ![scidept](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@scidept](https://www.ruby-forum.com/u/scidept)\
**Post date:** [December 2, 2005, 11:02am UTC](https://www.ruby-forum.com/t/file-column/91786/5 "2005-12-02T11:02:05Z")

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“You have a nil object when you didn’t expect it!  
The error occured while evaluating nil.image\_relative\_path”

You also get this or a similar error if the image field has not had a  
path/filename set.  
So you can either set a default value in the database, say  
“/images/default.jpg” or do  
image\_tag url\_for\_file\_column(“photo”, “image”) if @photo.image

Kris.