Wednesday, February 1, 2012

Re: Newbie django/python with C++ background wants enums

You could use a class, such as:

class TO_USE:
    Y = 'Yes'
    N = 'No'

if char == TO_USE.Y:
    pass


_Nik

On 2/1/2012 1:45 PM, NENAD CIKIC wrote:
Hello, the subject expresses my discomfort with certain python characteristics, given my background, and my lack of python knowledge.
Specifically lets say that I have a model with a Text field and char field. The char field is length 1 and says "use or do not use the text field". The char field can have Y or N values.
So using the admin interface I wanted to override the clean method but I did not want to write
if text.__len__==0 and char=='Y':
  raise exception

In C/C++ you would use enum for these sort of things. So I ended with defining in models.py something as:
TO_USE= (
    ('Y', 'Yes'),
    ('N', 'No'),
    )

class X(models.Model):
    txt= models.CharField(db_index=True,null=True, blank=True,max_length=30)
    use_txt= models.CharField(blank=False,max_length=1,default='D',choices=TO_USE)

and in admin.py something as
class XForm(forms.ModelForm):
    def clean(self):
        cleaned_data=super(XForm, self).clean()
        txt= cleaned_data['txt'].strip()
        use_txt=cleaned_data['use_txt'].strip()

        if txt.__len__()==0 and use_txt==TO_USE.__getitem__(0)[0]:
            raise forms.ValidationError('This is needed!')

        return cleaned_data

The part .__getitem__(0)[0] is not very readable. I have looked for enums in python, and if I have understood well, it seems they are not implemented.
What is the best way to do it in python for my problem, given that I do not want to write =='Y'.
Thanks
Nenad

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