fields.py

"""
Django field that autogenerate code for django.

/!\ Not tested with unit tests yet in this module
However, I tested it with unitests in a live django project and it did fine.
But don't take my word for it and use with care.

"""

import re

from django.db import models

from code_generator import generate_code, get_code_from_model, increment_base_10


class CodeField(models.CharField):
    """
        Store an ordinary text code to increment with the following 
    """

    
    def generate_code(self, **kwargs):
        return generate_code(get_code_from_model, model=self.model, 
                             field=self.attname, **kwargs)
    
    
    #TODO: find a cleaner way to do this and allow any argument to pass
    def __init__(self, *args, **kwargs):
    
        gen_kwargs = {}
        gen_kwargs['prefix'] = kwargs.pop('prefix', '')
        gen_kwargs['suffix'] = kwargs.pop('suffix', '')
        gen_kwargs['min_length'] = kwargs.pop('min_length', 3)
        gen_kwargs['inc'] = kwargs.pop('inc', 1)
        gen_kwargs['pad_with'] = kwargs.pop('pad_with', '0')
        gen_kwargs['default'] = kwargs.pop('default', '0')
        
        kwargs.setdefault('blank', True)
        kwargs.setdefault('unique', True)
    
        models.CharField.__init__(self, *args, **kwargs)
        
        self.gen_kwargs = gen_kwargs
        self.pattern = r'^(?:%(prefix)s)?\d+(?:%(suffix)s)?$' % gen_kwargs
        self.regexp = re.compile(self.pattern)
    
    def pre_save(self, model_instance, add):
    
        
        code = getattr(model_instance, self.attname, None)
        
        if not code:
        
            # todo: we can do that much better
            # check if the code match the prefix / suffix
            # get_code_from_model
            qs = model_instance.__class__.objects.all()
            code = ''            

            while not self.regexp.match(code):
                
                code = get_code_from_model(model=model_instance.__class__, qs=qs,
                                          field=self.attname, **self.gen_kwargs)
                qs = qs.exclude(**{self.attname:code})

            code = increment_base_10(code, **self.gen_kwargs)
        
        setattr(model_instance, self.attname, code)
        return code
        

    def value_to_string(self, obj):
        return getattr(obj, self.attname)