如何将带有分隔符的字符串转换为Python中的字符串列表？

Question

I'm querying a database and get this text:

"('username', '192.168.1.1', datetime.datetime(2013, 1, 3, 7, 18))"

I want to split into list like this:

['username', '192.168.1.1', datatime.datetime(2013, 1, 3, 7, 18)]

So, which way is the best way? I'm using Python 2.4.

Answer 1

One way would be to use eval and list :

>>> import datetime
>>> string = "('username', '192.168.1.1', datetime.datetime(2013, 1, 3, 7, 18))"
>>> list(eval(string))
['username', '192.168.1.1', datetime.datetime(2013, 1, 3, 7, 18)]

eval evaluates the string as a Python expression, here producing a tuple containing the two strings and a datetime instance. list converts this tuple to a list.

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Caution: eval will potentially execute any valid Python code, even malicious code. There are safer alternatives such as ast.literal_eval which could be used if you're not sure whether you trust what's in your database.

Answer 2

You can use maxsplit parameter of the split function:

your_string = "('username', '192.168.1.1', datetime.datetime(2013, 1, 3, 7, 18))"
your_string[1:-1].split(",", 2)

# Returns:
# ["'username'", " '192.168.1.1'", ' datetime.datetime(2013, 1, 3, 7, 18)']

Answer 3

As noted in jonrsharpe comment, it looks like you are falling in a trap you have just digged yourself.

Any correct database can give you the individual columns, and if you correctly do the query, you get them in proper format.

Assuming you can use a DB-API 2.0 described in PEP 249 , and assuming conn is an open connection to your database, you should do something like :

curs = conn.cursor()
curs.execute('SELECT name, ip, dat FROM tab')
t = curs.fetchone()

and t should directly be the tuple ('username', '192.168.1.1', datatime.datetime(2013, 1, 3, 7, 18)) (use list(t) if you need a list ...)