Django, Python, trying to change field values / attributes in object retrieved from DB objects.all call, not working


Question

I'm trying to change a specific field from a field in an object that I retrieved from a django db call.

class Dbobject ()
   def __init__(self):
       dbobject = Modelname.objects.all()
   def test (self):
       self.dbobject[0].fieldname = 'some new value'

then I am able to access a specific attribute like so:

objclass = Dbobject()
fieldvalue = dbobject.dbobject[0].fieldname

but I want to be able to use the "test" method of the Dbobject class to try to change the specific value on an object's attribute value, but it isn't changing it. I am stumped by this as this is how I thought I am supposed to change an object's attribute value.

1
1
7/2/2012 9:14:34 PM

Accepted Answer

I'm not sure if this is the problem or not, but I think you might be missing a save() method.

from models import Person
p = Person.objects.get(pk=100)
p.name = 'Rico'
p.save()      # <== This writes it to the db. Is this what you're missing?

Above is the simple case. Adapted for what you wrote above, it'd be like:

dbobject.dbobject[0].fieldname = 'some new value'
dbobject.dbobject[0].save()

or, I'd write it more like:

rec = dbobject.dbobject[0]
rec.fieldname = 'some new value'
rec.save()

Also note that depending on whether and how you are using transactions, you may or may not see a change to the database until you commit.

10
9/13/2010 10:51:04 PM

I am not totally sure what you are trying to achieve, but shouldn't it be something like:

class Dbobject ():
   def __init__(self):
       self.dbobject = Modelname.objects.all()
   def test (self):
       self.dbobject[0].fieldname = 'some new value'

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