Extract items from string in db

Steve D'Aprano steve+python at pearwood.info
Wed Mar 15 04:02:00 EDT 2017


On Wed, 15 Mar 2017 09:26 am, DFS wrote:

> I have a SQLite database with TEXT columns containing strings of the
> format:
> 
> ['Item1: Value1 has,comma','Item2: has'apostrophe','Item3: Value3']
> 
> The brackets are part of the string.

So in Python format, you have something like this:

s = "['Item1: Value1 has,comma','Item2: has'apostrophe','Item3: Value3']"
assert type(s) is str
assert s[0] == "["
assert s[-1] == "]"


Correct?

I can't help you in getting s out of the SQLite database. Below, you tell us
that you're extracting the string, but it isn't actually a string, it is a
tuple. You need to fix that.


> How can I unpack and access each item?
> Item1: Value1 has,comma
> Item2: has'apostrophe
> Item3: Value3


Is the string format documented anywhere?



> I tried this:
> db.execute("SELECT COLUMN FROM TABLE WHERE ID = ?;",(123,))
> vals = [db.fetchone()]
> for val in list(vals):
>     print val


There's no point wrapping the output of db.fetchone() in a list. And no
point converting vals to a list.

db.execute("SELECT COLUMN FROM TABLE WHERE ID = ?;", (123,))
vals = db.fetchone()
for val in vals:
    print type(val), val


What does it output now?



> but it just prints the string as is.
> 
> split(",") returns "tuple object has no attribute split"

If it is a tuple object, it isn't a string. It isn't both at once.





-- 
Steve
“Cheer up,” they said, “things could be worse.” So I cheered up, and sure
enough, things got worse.



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