Python/Django Concatenate a string depending on whether that string exists
django, python, string-concatenation
Solution
parts = (1, 'a', 'b', 2, 'c', 'd', None, 'f')
# parts = (self.house, self.suf, self.unit,
# self.stex, self.stdir, self.stname,
# self.stdes, self.stdessuf)
' '.join(str(part) for part in parts if part is not None)
# '1 a b 2 c d e f'
You just do a list comp, and check if any value is not None, and also convert them to a string so they join properly regardless of type.
Problem
I'm creating a property on a Django model called "address". I want address to consist of the concatenation of a number of fields I have on my model. The problem is that not all instances of this model will have values for all of these fields. So, I want to concatenate only those fields that have values. What is the best/most Pythonic way to do this? Here are the relevant fields from the model: ``` house = models.IntegerField('House Number', null=True, blank=True) suf = models.CharField('House Number Suffix', max_length=1, null=True, blank=True) unit = models.CharField('Address Unit', max_length=7, null=True, blank=True) stex = models.IntegerField('Address Extention', null=True, blank=True) stdir = models.CharField('Street Direction', max_length=254, null=True, blank=True) stnam = models.CharField('Street Name', max_length=30, null=True, blank=True) stdes = models.CharField('Street Designation', max_length=3, null=True, blank=True) stdessuf = models.CharField('Street Designation Suffix',max_length=1, null=True, blank=True) ``` I could just do something like this: ``` def _get_address(self): return "%s %s %s %s %s %s %s %s" % (self.house, self.suf, self.unit, self.stex, self.stdir, self.stname, self.stdes, self.stdessuf) ``` but then there would be extra blank spaces in the result. I could do a series of if statements and concatenate within each, but that seems ugly. What's the best way to handle this situation? Thanks.