Re: debugging server code problems in server code that is invoked via ajax request

[bruno desthuilliers]

On 25 fév, 17:06, Margie Roginski  wrote:
> Hi - thanks for your responses.  Was on vacation and forgot to check
> back on this thread.  The idea of middleware is good.  I'm not sure,
> however, if the views.py code generates an exception, that it can be
> caught by the middleware?  

How do you think Django display that nice error page instead of a raw
"Internal Servor Error" ?-)

http://docs.djangoproject.com/en/1.1/topics/http/middleware/#process-exception

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Re: debugging server code problems in server code that is invoked via ajax request

[David De La Harpe Golden]

Possibly useful tip:

Note that if you use request.is_ajax() in your django views, you can 
also use e.g. the "Modify Headers" firefox plugin to simply pretend to 
django that an ordinary request you've e.g. typed into your browser 
address bar is an "ajax" request, with a rule e.g.


Action   Name   ValueComment
"Modify" "X-Requested-With" "XMLHttpRequest" "Fake AJAX Request"

Quite handy (there's a gui for enabling/disabling rules with a click)

https://addons.mozilla.org/en-US/firefox/addon/967

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Re: debugging server code problems in server code that is invoked via ajax request

[Margie Roginski]

Hi - thanks for your responses.  Was on vacation and forgot to check
back on this thread.  The idea of middleware is good.  I'm not sure,
however, if the views.py code generates an exception, that it can be
caught by the middleware?  I guess the question is how to catch
exceptions.  The views.py code is invoked by the django code, so on a
normal request, that django code must catch the exception and then
send it as a response to the client.  On a non-ajax request, the
response just gets displayed in the browser.  But on an ajax request,
unless I do some special stuff, I guess that response doesn't get
displayed.  So the question becomes how to catch the exception and put
it somewhere useful, and I'm still not clear if I can use middleware
to do that.

One thing that I realize is that if I just make a request to the same
address that the ajax request is going to, then I do see the error
trace in my browser, so that's helpful and that's the tact I have been
taking lately.

Margie

On Feb 12, 2:33 am, bruno desthuilliers
 wrote:
> On Feb 11, 10:27 pm, MargieRoginski wrote:
>
> > I have a question about debugging django server side code in the case
> > where the request is an ajax request.
>
> From the server-side POV, a request is a request is a request. Truth
> is : there's no such thing as an "ajax request".
>
> >  For example I have an
> > autocomplete widget.  It makes a request to a particular url that
> > takes me to one of my views.py functions, get_users(request).  If I
> > have some sort of error in that function, I don't see the error
> > anywhere and it just silently fails.
>
> It's your client code that fails to handle the case properly.
>
> >  If I explicitly put that url
> > into the address bar then the error comes up in my browser, or if I
> > use pdb to put a break point and then step through my code, I see the
> > error.   In the case of an ajax request,
>
> cf above.
>
> > what happens to the error
> > from the server code and is there any way to see it?
>
> yes : look at the response content. Firebug is your friend - it lets
> you trace and inspect XMLHttpRequests and their responses. Also, you
> may want to have a "logging" middleware that logs unhandled errors -
> this is useful both in dev or in production.
>
> HTH

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Re: debugging server code problems in server code that is invoked via ajax request

[bruno desthuilliers]

On Feb 11, 10:27 pm, Margie Roginski  wrote:
> I have a question about debugging django server side code in the case
> where the request is an ajax request.

>From the server-side POV, a request is a request is a request. Truth
is : there's no such thing as an "ajax request".

>  For example I have an
> autocomplete widget.  It makes a request to a particular url that
> takes me to one of my views.py functions, get_users(request).  If I
> have some sort of error in that function, I don't see the error
> anywhere and it just silently fails.

It's your client code that fails to handle the case properly.

>  If I explicitly put that url
> into the address bar then the error comes up in my browser, or if I
> use pdb to put a break point and then step through my code, I see the
> error.   In the case of an ajax request,

cf above.

> what happens to the error
> from the server code and is there any way to see it?

yes : look at the response content. Firebug is your friend - it lets
you trace and inspect XMLHttpRequests and their responses. Also, you
may want to have a "logging" middleware that logs unhandled errors -
this is useful both in dev or in production.

HTH

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Re: debugging server code problems in server code that is invoked via ajax request

[Javier Guerra]

On Thu, Feb 11, 2010 at 4:31 PM, Javier Guerra  wrote:
> unfortunately, it doesn't render HTML responses...

i'm glad to report i was wrong!  it _does_ render content as HTML on a new tab.


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Javier

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Re: debugging server code problems in server code that is invoked via ajax request

[Javier Guerra]

On Thu, Feb 11, 2010 at 4:27 PM, Margie Roginski
 wrote:
> In the case of an ajax request, what happens to the error
> from the server code and is there any way to see it?

i use firebug.  it lets you see every http interaction. with contents and all.

unfortunately, it doesn't render HTML responses...

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Javier

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debugging server code problems in server code that is invoked via ajax request

[Margie Roginski]

I have a question about debugging django server side code in the case
where the request is an ajax request.  For example I have an
autocomplete widget.  It makes a request to a particular url that
takes me to one of my views.py functions, get_users(request).  If I
have some sort of error in that function, I don't see the error
anywhere and it just silently fails.  If I explicitly put that url
into the address bar then the error comes up in my browser, or if I
use pdb to put a break point and then step through my code, I see the
error.   In the case of an ajax request, what happens to the error
from the server code and is there any way to see it?

This is all using ./manage.py runserver.  I'm not concerned with the
deployment environment at all.

Margie

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