On Sun, 2007-10-21 at 04:47 -0700, Andreas Pfrengle wrote: > Hello group, > > I've stumbled upon sth. where I'm not sure if this is an intended > behaviour or not. I tried to dump my db-data to a json-fixture and > load it again, where I got the error that a float-value can't be > converted to Decimal (using postgres with psycopg2). I traced the > problem back and set up a Test-application with models.py, settings.py > and a little run.py that creates an entry in my test-db. I've pasted > all together with the fixture I get from dumpdata and the error when > trying to load it: > http://dpaste.com/hold/23003/ > > As far as I can see, the problem lies in the __init__ of the model. If > the float-value I create here would be created directly, everything is > fine and I get a string-conversion of the float-value in the fixture, > which I can load without problems. But in this case, even if I > manually put "" around the float and load it, the __init__ always > creates a new random value. Surely I could work around this problem by > taking the code out of __init__, but I'd like to know why django > behaves this way; or could it even be a bug?
This is normal Python behaviour. There's nothing Django-specific going on here. Firstly, Python won't create decimal objects out of a float, since the precision is not well-defined. So you can need a decimal object or a string in order for Python to coerce it to a decimal object in self.factor. Secondly, look at what happens when you create a Testtable instance, which the deserialiser is going to do by essentially doing the equivalent of Testtable(pk=1, factor=1.2345). First, Django's default __init__ method on the model class is run (line 8 in your paste) and then you replace self.factor with your own random number (lines 9 and 10). It's your own code doing exactly what you told it to do. Regards, Malcolm -- Telepath required. You know where to apply... http://www.pointy-stick.com/blog/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
