[mythtv-commits] Ticket #13299: Python Bindings fail to calculate date-time object

[MythTV]

#13299: Python Bindings fail to calculate date-time object
-------------------------------+--------------------------------
 Reporter:  rcrdnalor          |          Owner:  Raymond Wagner
     Type:  Patch - Bug Fix    |         Status:  new
 Priority:  minor              |      Milestone:  needs_triage
Component:  Bindings - Python  |        Version:  Unspecified
 Severity:  medium             |     Resolution:
 Keywords:                     |  Ticket locked:  0
-------------------------------+--------------------------------

Comment (by rcrdnalor):

 I'd like to attract more attention to this issue.

 This bug causes every meaningful call to the `Recorded` class to fail
 (using chanid and starttime), but with this patch installed, I can use all
 these fancy methods the `datetime.duck()` method was written for.\\

 With this patch, I get the same behavior as with my ubuntu 14.04 / mythtv
 fixes/0.27 installation,
 for example, for a recording '2102_20180606202400.ts' with valid database
 entry:

 {{{
 $ python2
 Python 2.7.15rc1 (default, Apr 15 2018, 21:51:34)
 >>> from MythTV import MythError, Recorded, MythDB, datetime
 >>> db = MythDB()
 >>>
 >>> # recording in database : 2102_20180606202400.ts
 >>> # local time : CEST = UTC+02:00
 >>> chanid = 2102
 >>> utc_mythtime   = 20180606202400
 >>> local_mythtime = 20180606222400
 >>> local_time_str = '2018-06-06 22:24:00'
 >>>
 >>> Recorded((chanid,local_mythtime), db =db)
 b'<Recorded 'WORLDjournal','2018-06-06 22:24:00+02:00' at 0x7fc746755ab8>'
 >>>
 >>> Recorded((chanid,local_time_str), db =db)
 b'<Recorded 'WORDjournal','2018-06-06 22:24:00+02:00' at 0x7fc744d25990>'
 }}}


 Without this patch, every of the above mentioned calls fail with:
 {{{
 ....
     raise MythError('DBData() could not read from database')
 MythTV.exceptions.MythError: DBData() could not read from database
 }}}

 I have to use some - non existing - intermediate time values to get the
 `Recorded` class loaded:
 Applying an offset of 1 hour (for whatever reason):
 {{{
 >>> Recorded((chanid,(local_mythtime-10000)), db =db)
 b'<Recorded 'WORLDjournal','2018-06-06 21:24:00+01:00' at 0x7fc341e97ab8>'
 >>> Recorded((chanid,'2018-06-06 21:24:00'), db =db)
 b'<Recorded 'WORLDjournal','2018-06-06 21:24:00+01:00' at 0x7fc340452ab8>'
 }}}
 This makes absolutely no sense.

 Please note:
 MythTV decided to keep the 'chanid, starttime' tuple to initialize the
 `Recorded` class of the Python Bindings.
 See commit ce1935b0ebc0918391f05893be82cd275cbd3969 and #12260.

 The property `Job(jobid, db=db).starttime` used when calling a python
 script triggered by a user job is not affected by this bug.

 Interesting observation:
 I have seen python scripts available in the wiki or in the forum
 implementing
 some - more or less useful - workarounds to circumvent this problem, like
 requiring date/time values and an offset as input on the command line for
 the starttime.
 But I found no message that complains about the broken datetime
 implementation in dt.py


 And, please, do not add an "But it works for me as it is." comment if you
 are living in UTC (GMT, BST) Zone ;-)\\

 Instead, try my patch and report the result.

-- 
Ticket URL: <https://code.mythtv.org/trac/ticket/13299#comment:4>
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