python+postgresql: Convert string literal to regex

Question

I want to execute a query where I match a column name using a regex to my variable, s. s is a string literal and may contain things like ?, *, ., etc. I want to convert s so that ? turns into .{0,3}, so that all of its remaining regex symbols remain literals, and then add .* to the end. examples:

Hi -> Hi.*
Fo?ar -> Fo.{0,3}ar.*
F.a*rx -> F\.a\*rx.*
F.a?*rx -> F\.a.{0,3}\*rx

What's the best way to do this? Mostly I'm unsure how to quote a string literal so the regex symbols aren't interpreted as regex symbols (e.g. . -> \.).

nosklo · Accepted Answer · 2011-03-24 20:44:46Z

4

print '.{0,3}'.join(re.escape(part) for part in s.split('?')) + '.*'

answered Mar 24, 2011 at 20:44

nosklo

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Mike Lewis · Accepted Answer · 2011-03-24 20:46:24Z

1

Use the re.escape(string) method.

Which states:

Return string with all non-alphanumerics backslashed; this is useful if you want to match an arbitrary literal string that may have regular expression metacharacters in it.

Check out the re module page.

answered Mar 24, 2011 at 20:46

Mike Lewis

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1 Comment

Claudiu Over a year ago

ah 'escape' is the word, i was thinking 'quote'

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