Question

So I am trying to put the result of a query in a string. Let’s say row by row (I don’t need all the fields by the way), but that’s not the point. I am using python against a sqlite db.

the problem is that when some of the fields are null, python will write None instead of “” or some blank neutral thing.

example:

   t = "%s %s %s %s" % (field[1],field[2],field[3],field[4])

If field[3] is null for instance, t will be something like

"string1 string2 None string4"

instead of

"string1 string2 string4"

yes I would need to remove also the double space in case. I cannot just replace “None” with “” because some string might contain itself “None” since it is a common word. Of course I don’t have only 4 field, they are a lot, and I am not trying to import every field of the row, only specific ones. I need a fast and easy way to fix this behavior. I cannot manually check if each field is None, that’s insane. I cannot use

str.strip(field[i])

because when the field is None I get an error.

what could be a good approach?

Answer 1

There is the str.replace option if “None ” is unique to NULL fields:

>>> "string1 string2 None string4".replace('None ', '')
'string1 string2 string4'

Or you can pre-filter the strings:

>>> fields = ['string0', 'string1', 'string2', None, 'string4']
>>> fields_out = filter(lambda f: f is not None, fields[1:])
>>> template = ' '.join('%s' for field in fields_out)
>>> template % tuple(fields_out)
'string1 string2 string4'