You can add methods to your model class
class Container(models.Model):
name = models.CharField(max_length=128)
capacity = models.IntegerField()
contains = models.IntegerField()
def usage_percentage():
return 100.0 * self.contains / self.capacity
And in your template
{% if object_list %}
<table>
{% for o in object_list %}
<tr>
<td>{{ o.name }}</td> <td>{{ o.capacity }}</td> <td>{{ o.contains
}}</td> <td> {{ o.usage_percentage }} </td>
</tr>
{% endfor %}
</table>
{% endif %}
On Tue, Jun 9, 2015 at 11:03 PM, JLeary <[email protected]>
wrote:
> Hi.
> Total Django Newbie here... and pretty new to Python too.
> Anyway, I have this simple problem, and I've been reading documentation
> all afternoon but just can't come up with a simple solution.
>
> How can I display calculated values from the Model vales store in the
> database?
> Like, a percentage of two numbers?
>
> For instance;
>
> # myapp/models.py
> class Container(models.Model):
> name = models.CharField(max_length=128)
> capacity = models.IntegerField()
> contains = models.IntegerField()
>
>
> python manage.py shell
> >>> Container(name="big bucket", capacity=100, contains=22).save()
> >>> Container(name="small bucket", capacity=50, contains=48).save()
> >>> Container(name="medium bucket", capacity=75, contains=13).save()
>
>
> # myapp/views.py
> from django.http import HttpResponse
> from django.template import RequestContext, loader
> from .models import Container
> def index(request):
> object_list = Container.objects.all()
> template = loader.get_template('myapp/index.html')
> context = RequestContext(request, {
> 'object_list': object_list,
> })
> return HttpResponse(template.render(context))
>
>
> # myapp/templates/myapp/index.html
> {% if object_list %}
> <table>
> {% for o in object_list %}
> <tr>
> <td>{{ o.name }}</td> <td>{{ o.capacity }}</td> <td>{{ o.contains
> }}</td>
> </tr>
> {% endfor %}
> </table>
> {% endif %}
>
> .
>
>
> So, all is fine when I create a simple view template to display the NAME,
> CAPACITY, and CONTAINS info for each object.
>
> What I really want... is the Percent-Full of each Container to be
> displayed.
> But, I'm stumped as to how I can do this.
>
> I've tried creating a sub-class of Container, that contained methods to
> return the percentages, but was unable to get it to work.
>
> Any input is appreciated.
> Thanks.
>
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