On 24 mar, 06:39, Daniel <unagimiy...@gmail.com> wrote:
> Hi there,
>
> I'm reading the django book and they say that you can validate a form
> like this in one line, checking for missing keys and missing data:
>
> if not request.POST.get('subject', ' ')
> errors.append('enter a subject')
Are you sure this is the very exact code ? IMHO it's probably
something like:
if not request.POST.get('subject', ''):
errors.append('enter a subject')
> I'm not sure how to read that line of code, though. Can someone
> explain please?
>
> Is this checking if the subject key is blank or nil and then appending
> the error?
Yeps.
> But if the subject key is nil,
s/nil/missing/
> then the default value for the subject
> key is made to be blank (' ')?
Would be (and probably is) '', not ' ' (cf above and below).
wrt/ your question, it's not clear whether you ask if - in the case of
a missing key - .get() will actually update the request.POST object or
if it will just return the default instead. But anyway: request.POST
is documented has being mostly "a dict-like object" - IOW an object
that mostly behave like a regular python dict. If you don't know how a
regular python dict behave, then it's time you start learning Python.
Else nothing in Django will make sense to you.
> How does this code check for a non-existent subject key and the case
> that the subject key exists, but is just empty?
I give you two clues:
1/ dict.get(<key>[, default=None) returns either the value for <key>
or default if <key> is not in dict.
2/ an empty string has a false value in a boolean test.
And a general advice: do at least the official Python intro tutorial.
You can't expect to make proper use a framework if you don't learn the
language it's based on.
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