On Thu, 28 Nov 2013 10:08:30 -0500, Roy Smith wrote:
> In article <34479463-b8a8-4417-9989-cd2936946...@googlegroups.com>,
> Victor Hooi <victorh...@gmail.com> wrote:
>
>> cur.executemany("INSERT INTO foobar_foobar_files VALUES (?)",
>> [[os.path.relpath(filename, foobar_input_folder)]
>> for filename in filenames])
>
> I don't often write raw SQL embedded in Python. I'm much more likely to
> use some sort of ORM layer. But, if I were doing this, I would break it
> up something like:
>
>
>
> There's a few different strategies I employed there. My first thought
> was a logical break of computing the list of pathnames vs. inserting
> them into the database. That got me here:
>
> paths = [[os.path.relpath(filename, foobar_input_folder)] \
> for filename in filenames]
> cur.executemany("INSERT INTO foobar_foobar_files VALUES (?)",
> paths)
>
> I wouldn't have actually broken the first line with the backslash, but
> I'm doing that to appease my news posting software.
>
> My next step would be some simple textual changes; I'd get rid of the
> overly-line variable names. In general, I don't like very short
> variable names, but I'm OK with them as long as the scope is very small,
> as it is here:
>
> paths = [[os.path.relpath(fn, folder)] for fn in filenames]
> cur.executemany("INSERT INTO foobar_foobar_files VALUES (?)",
> paths)
>
> I'd probably factor out the double lookup of os.path.relpath. I think
> this is easier to read:
>
> relpath = os.path.relpath paths = [[relpath(fn, folder)] for fn in
> filenames] cur.executemany("INSERT INTO foobar_foobar_files VALUES
> (?)",
> paths)
>
> If filenames was a very long list, it would also be a little bit faster
> to execute, but that's such a small factor as to probably be
> unmeasurable.
>
> And, finally, I'd probably move one set of square brackets down into the
> SQL statement. It really makes more sense there anyway; the bundling up
> of the arguments into a sequence is more a part of the database API than
> it is inherent to the data.
>
> relpath = os.path.relpath paths = [relpath(fn, foobar_input_folder)
> for fn in filenames]
> cur.executemany("INSERT INTO foobar_foobar_files VALUES (?)",
> [paths])
I had a problem similar to this some time ago. Someone (here) suggested
textwrap.dedent, which for me was just the ticket.
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