CODEWITHSUNDEEP
pythondjangodjango-modelsdjango-model-field
vcruvinelr
vcruvinelr

Reputation: 126

'Calculate' variables as fields in the Django model

I have a simple model:

class Atividade(models.Model):
    valor_brl = models.DecimalField(max_digits=14, decimal_places=2)
    dolar_ref = models.DecimalField(max_digits=14, decimal_places=2)
    valor_usd = models.DecimalField(max_digits=14, decimal_places=2)

I create after a method to calculate a new value using the two fields from the model

@property
def valor_usd_novo(self):
    valor_usd_novo = self.valor_brl / self.dolar_ref
    return valor_usd_novo

If I call {{ valor_usd_novo }} I get the result I want.

After this I create the save() method, to save valor_usd_novo result in valor_usd field from the model.

def save(self, *args, **kwargs):
    self.valor_usd = self.valor_usd_novo()
    super(Atividade, self).save(*args, **kwargs)

The point is that when I call valor_usd I got no results and the database do not update with the result from valor_usd_novo method.

What I missing here?

Upvotes: 0

Views: 45

Answers (2)

vcruvinelr
vcruvinelr

Reputation: 126

I really appreciate all the help. I found the solution for the problem:

def new_value(self, *args, **kwargs):
    self.valor_usd = self.valor_usd_novo
    super(Atividade, self).save(*args, **kwargs)
    return self.valor_usd

With this code when I call {{atividade.new_value}} in the template I got the new value and the value in self.valor_usd update.

Upvotes: 0

heemayl
heemayl

Reputation: 41987

valod_usd_novo is a property, so you need treat it like an attribute, not a method. Hence, drop the call and refer as an attribute:

def save(self, *args, **kwargs):
    self.valor_usd = self.valor_usd_novo  # not self.valod_usd_novo()

Upvotes: 1

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