I'm new to django, and as a learning app, I'm building an expense logging application.
In my models I have three classes that look like this (I simplified them slightly for brevity):
class AbstractExpense(models.Model):
description = models.CharField(max_length=100)
amount = models.IntegerField()
category = models.ForeignKey('Category')
tags = models.ManyToManyField('Tag')
insert_date = models.DateTimeField(auto_now=True)
class Meta(object):
abstract = True
class Expense(AbstractExpense):
date = models.DateField('Date')
class RecurringExpense(AbstractExpense):
FREQUENCY_CHOICES = (('D', 'daily'),
('W', 'weekly'),
('M', 'monthly'),
('Y', 'yearly'))
start_date = models.DateField(blank=False)
end_date = models.DateField(blank=True, null=True)
last_check = models.DateField(blank=True, null=True)
frequency = models.CharField(blank=False, max_length=1, choices=FREQUENCY_CHOICES)
RecurringExpense
is just a template: when the system realises that the time to insert a recurring expense (e.g.: the rent) it should take the info in the template and copy them in a new instance of the Expense
class. Here's the relevant bit from the RecurringExpense
method in charge of the work:
Expense(description=self.description,
amount=self.amount,
category=self.category,
# tags=self.tags,
date=expense_date).save()
The above works flawlessly, but if I uncomment the tags=self.tags
line, django complains and throw the following error:
Exception Type: TypeError
Exception Value: 'tags' is an invalid keyword argument for this function
Exception Location: <snip>/django/db/models/base.py in __init__, line 367
I know I could create a loop to work around this problem, but I wonder if there is a more elegant way that would allow me to perform the same at once....
The simpliest method I could come up with:
e = Expense(description=self.description,
amount=self.amount,
category=self.category,
date=expense_date)
e.save()
e.tags = self.tags.all()