On Thursday, 13 October 2011 23:58:00 UTC+1, Victor Hooi wrote:
>
> Hi,
>
> I have Django model and in one of the fields I need to store a regex string
> that I can later use.
>
> class Foo(models.Model):
> name = models.CharField(max_length=30, unique=True)
> regex_string = models.TextField()
>
>
> So for example, the regex_string field might be set to:
>
> r'\d{2}'
>
>
> I then try to retrieve this later, compile it as a regex expression and use
> it - however, it doesn't seem to work as planned:
>
> >>> pattern = re.compile(ham.regex_string)
> >>> print(pattern.match("22"))
> None
>
>
> Obviously if I pass the raw string literal in directly, it works fine:
>
> >>> pattern = re.compile(r'\d{2}')
> >>> pattern.match("22")
> <_sre.SRE_Match object at 0x1505100>
>
>
> If I actually print ham.regex_string, it returns:
>
> u"r'\\d{2}'"
>
>
> So it's a unicode string, but for some reason the backslashes are
> doubled-up?
>
> What I actually need is a way to store a regex raw string literal, so that
> I can retrieve it later and use it in a regex.
>
> Is there a better way of doing this?
>
> Cheers,
> Victor
>
So how did you save it in the first place? You don't actually want the `r`
and the single quotes, they're just for when you specify the literal in your
code. If you did
foo.regex_string = r'\d{2}'
it should come out the other side OK. When you print the string in your
console, it'll give the doubled-backslash, but that's just the way Python
displays them - it would do the same with the original raw string.
--
DR.
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