# How to debug the rendering in Rails?

**URL:** <https://www.ruby-forum.com/t/how-to-debug-the-rendering-in-rails/60939>\
**Category:** Rails\
**Created:** [May 18, 2006, 6:22pm UTC](https://www.ruby-forum.com/t/how-to-debug-the-rendering-in-rails/60939 "2006-05-18T18:22:04Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Mariano\_K](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/eada6e/32.png) [@Mariano\_K](https://www.ruby-forum.com/u/Mariano_K)\
**Post date:** [May 18, 2006, 6:22pm UTC](https://www.ruby-forum.com/t/how-to-debug-the-rendering-in-rails/60939/1 "2006-05-18T18:22:04Z")

</div>

Hi,

I have some controller code like this:

```
def mailing_lists
@ml = MailingList.find_by_identifier(@params[:id])
@messages = @ml.messages
@headers["Content-Type"] = "application/atom+xml"
@response.headers['Last-Modified'] =

```

@messages.last.created\_on.httpdateunless @  
messages.empty?

```
minTime = Time.rfc2822(@request.env["HTTP_IF_MODIFIED_SINCE"]) 

```

rescue  
nil  
if minTime and @messages.first.created\_on \<= minTime  
render :text =\> ‘Not Modified’, :status =\> 304  
end  
end

This works fine in development, but not in production. The funny thing  
is  
that tailing production.log I can see that http status code 200 or 304  
is  
returned, but in the apache access log I can see that 500 is returned.  
The  
latter is what I can also see in the browser.

I am wondering how to debug that… Putting rescues anywhere in the  
above  
mentionend code has no effect. So I guess it is in the render method  
that is  
called when no other explicit render invocation happend before?

I also don’t see anything I print with puts. In the dev environment  
and  
webrick I can see this output in the webrick console, but in production  
(apache, fastcgi) I don’t know where to find this output. access.log,  
error.log, production.log and the fastcgi logs don’t contain my puts  
output.

Any ideas?

Cheers,  
Mariano

---

<div class="post-metadata">

**Author:** ![Mariano\_K](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/eada6e/32.png) [@Mariano\_K](https://www.ruby-forum.com/u/Mariano_K)\
**Post date:** [May 18, 2006, 7:17pm UTC](https://www.ruby-forum.com/t/how-to-debug-the-rendering-in-rails/60939/2 "2006-05-18T19:17:32Z")

</div>

On May 18, 2006, at 11:20 AM, Mariano K. wrote:

> ```
> minTime = Time.rfc2822(@request.env["HTTP_IF_MODIFIED_SINCE"])  
> 
> ```
> 
> rescue nil  
> if minTime and @ messages.first.created\_on \<= minTime  
> render :text =\> ‘Not Modified’, :status =\> 304  
> end  
> end

I don’t know how to answer your main question. However, in your code  
above, isn’t the first line incorrect? Shouldn’t it be:

@ml = MailingList.find\_by\_identifier(params[:id]) # \<-- notice no @  
in front of params, it’s not a class instance var

---

<div class="post-metadata">

**Author:** ![Mariano\_K](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/eada6e/32.png) [@Mariano\_K](https://www.ruby-forum.com/u/Mariano_K)\
**Post date:** [May 18, 2006, 7:45pm UTC](https://www.ruby-forum.com/t/how-to-debug-the-rendering-in-rails/60939/3 "2006-05-18T19:45:32Z")

</div>

Hi,

yes, that is ugly… I will clean that up.

Also for the use of @headers and of course @response.headers is also  
not  
nice to use. Still it is valid code.

So I am still looking how I can get some more debug output about the  
rendering.

Cheers,  
Mariano