tags:

views:

40

answers:

4
Q: 

Django request.GET

It seems I cant make this example print "You submitted nothing!". Everytime I submit an empty form it says:

You submitted: u''

instead of:

You submitted nothing!

Where did I go wrong?

views.py

def search(request):
    if 'q' in request.GET:
        message = 'You submitted: %r' % request.GET['q']
    else:
        message = 'You submitted nothing!'

    return HttpResponse(message)

template: 

<html>
    <head>
        <title> Search </title>
    </head>
    <body>
        <form action="/search/"  method="get" >
        <input type="text" name = "q">
        <input type="submit"value="Search"/>
        </form>
    </body>
</html>
+2  A: 

since your form has a field called 'q', leaving it blank still sends an empty string.

try

if 'q' in request.GET and request.GET['q'] != "" :
     message
else
     error message
second  2010-08-17 09:08:06
+3  A: 

Calling /search/ should result in "you submitted nothing", but calling /search/?q= on the other hand should result in "you submitted u''"

Browsers have to add the q= even when it's empty, because they have to include all fields which are part of the form. Only if you do some DOM manipulation in Javascript (or a custom javascript submit action), you might get such a behavior, but only if the user has javascript enabled. So you should probably simply test for non-empty strings, e.g:

if request.GET.get('q'):
    message = 'You submitted: %r' % request.GET['q']
else:
    message = 'You submitted nothing!'
tux21b  2010-08-17 09:10:29
Wouldn't this throw exception if q does not exists in dict?
rebus  2010-08-17 09:16:35
No, calling `dict.get(key, default=None)` will either return the value stored for the key, or the default otherwise. In that case `None` is returned and both, `u''` and `None` evaluate to `False`. So, get() is a useful method when you don't want an exception to be thrown.
tux21b  2010-08-17 09:27:59
Oooh! You are right, not sure what I was thinking this morning.
rebus  2010-08-17 10:36:06
Ok. Thanks. Not sure what the second get is doing here. But it worked. So I will find out now.
MacPython  2010-08-17 10:41:41
`get()` is a method of the `dict` type. Like lists have methods like `append()` and `sort()`, dicts are having methods like `iterkeys()`, `iteritems()` and `get()` (to only mention a few of them). It's just coincidence that your dict is also called `GET`.
tux21b  2010-08-17 11:35:04
+1  A:  
q = request.GET.get("q", None)
if q:
    message = 'q= %s' % q
else:
    message = 'Empty'
rebus  2010-08-17 09:17:54
A: 

In python, None, 0, ""(empty string), False are all accepted None.

So:

if request.GET['q']: // true if q contains anything but not ""
    message
else : //// since this returns "" ant this is equals to None
    error
FallenAngel  2010-08-17 09:21:34

related questions

Django: Print url of view without hardcoding the url
Django Calendar Widget?
Can the HTTP version or headers affect the visual appearance of a web page?
Project design / FS layout for large django projects
Extending the User model with custom fields in Django
How to generate urls in django
Always including the user in the django template context
Screencasts for Django/Python?
Using Django time/date widgets in custom form
How do I add data to an existing model in Django?
Setup django with WSGI and apache
Altering database tables in Django
Django Templates and variable attributes.
Django ImageField core=False in newforms admin
How can I render a tree structure (recursive) using a django template?
Cleanest & Fastest server setup for Django
Unicode vs UTF-8 confusion in Python / Django?
Does Hostmonster support Django
Specifying a mySQL ENUM in a Django model
Represent Ordering in a Relational Database
updating an auto_now DateTimeField in a parent model w/ Django
Version track, automate DB schema changes with django
Learning Ruby on Rails any good for Grails?
What Hosting Service is best for Django applications?
Class views in Django