Daniel,
On the object dynamicness, I think my brain malfunctioned because somehow I new
this, but you just helped me remove 3 fields on my product model ... ;-)
As far as placing the calculation in the view or the template (thanks on the
example btw). An invoice is now generated in html but in the future I want to
be able to generate them in pdf or ms word as well. So doing the work in the
view seems like easier transition to those filetypes in the future.
Regards,
Gerard.
Daniel Roseman wrote:
> On Sep 25, 10:33 am, Gerard Petersen <[EMAIL PROTECTED]> wrote:
>> Hi All,
>>
>> I'm finding myself creating more and more fields in a model to keep my
>> templates clean. Since it's merely temporary calculated data, and not data
>> to store permanently it feels like the wrong place. An example:
>>
>> I have a product model (child object of an order model). The product has a
>> 'per_price' and 'amount' field that get filled by the user. I gave the
>> product an extra field called 'total_price' where I store 'amount *
>> per_price' just before my view and my template come together. This way all
>> that's needed to display an invoice is in the objects list.
>>
>> Calculating this in the template also doesn't seem the way. For MVC's sake I
>> belief this belongs in the view, but then it's to late (read: there's no
>> field on the object) to store temporary stuff.
>>
>> The Q: How does one relate temporary data to objects in a list, before it's
>> rendered in a template?
>>
>> Thanx a lot,
>>
>> Gerard.
>>
>> Some source snippets if it's not clear:
>>
>> # ---- Model
>> class Product(models.Model):
>> per_price = models.DecimalField('Product price', max_digits=15,
>> decimal_places=2)
>> total_price = models.DecimalField('Calculated', max_digits=15,
>> decimal_places=2, editable=False, null=True)
>> amount = models.IntegerField('#', max_length=10)
>>
>> # ---- View
>> def download_order(request, order_id):
>> for p in product_list:
>> # Calculate product totals
>> p.total = Decimal(p.amount * p.per_price)
>>
>> # ---- Template
>> {% for product in product_list %}
>> <tr class="{% cycle 'row1' 'row2' %}">
>> <td>{{ product.name }}</td>
>> <td>{{ product.description }}</td>
>> <td>{{ product.total }}</td>
>>
>
>
> Well I'd disagree that you shouldn't do this in the template - this is
> exactly the sort of thing that could go there.
>
> However if you're committed to doing it in the view, you should
> remember that model instances are just Python objects, so are dynamic.
> It's perfectly legal to assign to an attribute on the model which
> isn't defined elsewhere. So even if you didn't have a total_price
> field, you could still do p.total_price = whatever and then access
> that in the template.
>
> Another way of doing it would be to add both the total and the model
> to a list:
> products_totals = [(p, p.amount * p.per_price) for p in product_list]
>
> and in the template:
> {% for product in product_list %}
> {{ product.0.name }}
> {{ product.0.description }}
> {{ product.1 }}
>
> ... or you could even make it a list of dictionaries so that the
> template is clearer.
> --
> DR.
> >
--
urls = { 'fun': 'www.zonderbroodje.nl', 'tech': 'www.gp-net.nl' }
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