On Sat, 2006-05-20 at 04:15 -0700, PythonistL wrote:
> Question 1
> I noticed in MySQL that if a table field has NULL value, then I can
> test in Python with that filed with None.
> In otherwords NULL in MySQL is the same as None. in Python
> Is it so or am I wrong?
That is the way Django does the mapping, yes. If the database field is
NULL, the attribute in the object will be set to None.
> Question 2.
> I also would like to test NULL values in my templates. So I would like
> to use something like this:
> {% ifequal Price NULL %}
> .....
> ....
> {%else%}
> .....
> {% endifequal %}
>
> Is that possible? NULL doesn't work there neither None.What shall I use
> in the template to test NULL values in MySQL?
It is probably making life a little harder than necessary to think of
this as testing against the database. You are testing against an
attribute in the model, really. So think in Python terms, not SQL inside
templates.
The simplest way to test this is just to test if it's True or False, so
"{% if Price %}" should work. The only way something will not pass this
if-test is if it is non-existant, None, and empty string or a boolean
field with a value of False. So you {% else %} block will only be
executed if Price was NULL in the database.
Best wishes,
Malcolm
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Subject: Re: NULL vs.None
From: Malcolm Tredinnick <[EMAIL PROTECTED]>
To: django-users@googlegroups.com
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Date: Sat, 20 May 2006 21:59:53 +1000
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On Sat, 2006-05-20 at 04:15 -0700, PythonistL wrote:
> Question 1
> I noticed in MySQL that if a table field has NULL value, then I can
> test in Python with that filed with None.
> In otherwords NULL in MySQL is the same as None. in Python
> Is it so or am I wrong?
That is the way Django does the mapping, yes. If the database field is
NULL, the attribute in the object will be set to None.
> Question 2.
> I also would like to test NULL values in my templates. So I would like
> to use something like this:
> {% ifequal Price NULL %}
> .....
> ....
> {%else%}
> .....
> {% endifequal %}
>
> Is that possible? NULL doesn't work there neither None.What shall I use
> in the template to test NULL values in MySQL?
It is probably making life a little harder than necessary to think of
this as testing against the database. You are testing against an
attribute in the model, really. So think in Python terms, not SQL inside
templates.
The simplest way to test this is just to test if it's True or False, so
"{% if Price %}" should work. The only way something will not pass this
if-test is if it is non-existant, None, and empty string or a boolean
field with a value of False. So you {% else %} block will only be
executed if Price was NULL in the database.
Best wishes,
Malcolm
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