Question

I’m parsing an atom feed. There is an updated tag in the feed. It’s value is 2012-05-20T02:24:56Z. I insert this information in a table in this manner.

cursor.execute('Insert into Timing (LastUpdatedTime) Values(?)',
                (testFeed.feed.updated,))

After that I obtain the value from table and convert it into datetime in this way

cursor.execute("Select LastUpdatedTime from Timing")
lastUpdatedTime=datetime.strptime(list(cursor.fetchone())[0],
                '%Y-%m-%dT%H:%M:%SZ').isoformat()

The value of lastUpdatedTime is 2012-05-20T02:24:56

Now when I compare the value of testFeed.feed.updated with lastUpdatedTime to check if the feed had any new entries my comparison is giving output which I fail to comprehend.

print testFeed.feed.updated == lastUpdatedTime

This returns false
print testFeed.feed.updated > lastUpdatedTime

This returns true.
Values of variables when comparing:
testFeed.feed.updated=2012-05-20T02:24:56Z
lastUpdatedTime=2012-05-20T02:24:56

The column in database is of type text.

type of testFeed.feed.updated is unicode

type of lastUpdatedTime is string

Using python 2.7.2, working on Ubuntu 11.10

It works after converting the unicode object to datetime
currentFeedTime=datetime.strptime(str(testfeed.feed.updated),'%Y-%m-%dT%H:%M:%SZ').isoformat() and then to do the comparison with previous time.

Answer 1

The behavior you’re seeing makes sense to me, since testFeed.feed.updated has an extra ‘Z’ at the end.

Having said that, if you’re doing date/time comparison, I think you’re better off converting both dates to datetime.datetime, so something along the lines of:

For lastUpdatedTime

cursor.execute("Select LastUpdatedTime from Timing")
# Note that I'm not converting this to a string.
lastUpdatedTime=datetime.strptime(list(cursor.fetchone())[0],'%Y-%m-%dT%H:%M:%SZ')

And instead of testFeed.feed.updated:

feedUpdatedTime=datetime.strptime(testFeed.feed.updated,'%Y-%m-%dT%H:%M:%SZ')

And then to compare the two:

print feedUpdatedTime == lastUpdatedTime