# coding = utf-8 """ Package containing functions to support the templates. @author Marcos Thomaz da Silva - marcosthomazs@gmail.com """ __author__ = 'Marcos Thomaz da Silva - marcosthomazs@gmail.com' class Cel(object): """ Class Helper used to store summaries """ value = uval = None def __add__(self,val): if self.value: self.value = self.value + val else: self.value = val self.uval = val return val def __str__(self): return self.uval def __unicode__(self): return self.uval @property def total(self): return self.value def reset(self): self.value = self.uval = None return self class VirtualSummary(object): """ Class to be instantiated in views and used within the templates. Usage (only in django templates): vs = VirtualSummary() {{ vs. }} = Create a new virtual field to store the summary {{ vs.|add: }} = Use the fielter "add" to realize the sum. {{ vs.total__ }} = returns the result of the sum {{ vs.reset__ }} = reset the sum and return None. Used for realize summary in groups/subgroups Complete Example: ================================================ class Sale(models.Model): product = models.ForeignKey(Product) quantity = models.IntegerField() value = models.DecimalField('Unitary Value', max_digits=7, decimal_places=2) @property def subtotal(self): return self.quantity * self.value def __unicode__(self): return self.product.name def myview(request): vtable = VirtualSummary() my_sales = Sale.objects.all() return render(request, 'your_template.html' , locals()) ======= your_template.html ===== {% for sale in my_sales %} {% endfor %}

Product	Quantity	Un.Value	Subtotal
{{ sale.product }}	{{ vtable.qty\|add:sale.quantity }}	{{ vtable.unval\|add:sale.value }}	{{ vtable.subtot\|add:sale.subtotal }}
Total	{{ vtable.total__qty }}	{{ vtable.total__unval }}	{{ vtable.total__subtot }}

""" __values = {} # TODO Another operations: Subtraction, Average and Median def __getattr__(self, name): if name[:2] == '__' : return super(VirtualSummary, self).__getattr__(name) elif '__' in name: data = name.split('__') if data[0] == 'total': return self.__values[data[1]].total elif data[0] == 'reset': return self.__values[data[1]].reset() if not (name in self.__values): self.__values[name] = Cel() return self.__values[name]