DB Error in mythtv-setup and QString initialization

[Klaas de Waal]

A channelscan with mythtv-setup gives the following error messages, one for each channel:

DB Error (MSqlQuery):
Query was:
INSERT INTO channelscan_channel  (  scanid,             transportid,                                mplex_id,           source_id,          channel_id,             callsign,           service_name,       chan_num,               service_id,         atsc_major_channel, atsc_minor_channel,     use_on_air_guide,   hidden,             hidden_in_guide,        freqid,             icon,               tvformat,               xmltvid,            pat_tsid,           vct_tsid,               vct_chan_tsid,      sdt_tsid,           orig_netid,             netid,              si_standard,        in_channels_conf,       in_pat,             in_pmt,             in_vct,                 in_nit,             in_sdt,             is_encrypted,           is_data_service,    is_audio_service,   is_opencable,           could_be_opencable, decryption_status,  default_authority    )  VALUES  ( ?,            ?,                               ?,          ?,         ?,            ?,          ?,      ?,              ?,        ?,?,    ?,  ?,            ?,       ?,            ?,              ?,              ?,           ?,          ?,              ?,     ?,          ?,            ?,             ?,       ?,      ?,            ?,            ?,                ?,            ?,            ?,          ?,   ?,  ?,          ?,?, ?    );
Bindings were:
:ATSC_MAJOR_CHANNEL=0, :ATSC_MINOR_CHANNEL=0, :CALLSIGN="Penthouse HD1",
:CHANNEL_ID=0, :CHAN_NUM="792", :COULD_BE_OPENCABLE=false, :DECRYPTION_STATUS=2,
:DEFAULT_AUTHORITY=NULL, :FREQID="", :HIDDEN=false, :HIDDEN_IN_GUIDE=false,
:ICON=NULL, :IN_CHANNELS_CONF=false, :IN_NIT=true, :IN_PAT=true, :IN_PMT=true,
:IN_SDT=true, :IN_VCT=false, :IS_AUDIO_SERVICE=false, :IS_DATA_SERVICE=false,
:IS_ENCRYPTED=true, :IS_OPEBCABLE=false, :MPLEX_ID=43, :NETID=5555,
:ORIG_NETID=1536, :PAT
2019-03-03 21:20:13.973048 E  Original query failed, but resend with empty strings in place of NULL strings worked.

This message is caused by database access with QString variables which are NULL. There is an error catching mechanism present that replaces each NULL strings with an empty string. The last line in the message above states that this is done and that then the database access succeeded.

This problem is caused by the recent change to move initialization to the header files. This in itself should and does not make any difference, however, the initializations for the QString members of ChannelInsertInfo? in channelinfo.cpp/.h have been lost in this process.

This can be found in the following commit:
​https://github.com/MythTV/mythtv/commit/4d5526816f5c5d5ddbf52f960b597afbf5b31fea#diff-0500d09455f90efc1704bfbb28b33aab

The obvious solution is to restore the initialization of ChannelInsertinfo?.

A patch for this is attached.

[Klaas de Waal]

Restore initialization of QString members of ChannelInsertInfo?

[David Hampton <mythtv@…>]

In fcc1aa522/mythtv:

Catch and fix uninitialized QStrings passed to SQL code.

Most of Qt5 treats an uninitialized string and an empty string as the
same thing. QSqlQuery doesn't, storing NULL for the former and "" for
the latter. Add a new function for storing a non-null database field
that will store both of these QStrings as "".

Fixes #13420

[jpilk]

Line 355 in channelinfo.cpp looks like a preexisting typo ?

query.bindValue(":IS_OPEBCABLE", m_is_opencable);

[David Hampton]

Yes, but a consistent typo (the same in two places) so it worked properly. :-)

[David Hampton <mythtv@…>]

In 19a51cb405/mythtv:

Catch and fix uninitialized QStrings passed to SQL code.

Most of Qt5 treats an uninitialized string and an empty string as the
same thing. QSqlQuery doesn't, storing NULL for the former and "" for
the latter. Add a new function for storing a non-null database field
that will store both of these QStrings as "".

Fixes #13420

[Klaas de Waal <kdewaal@…>]

In 28e98a80ed/mythtv:

More use of bindValueNoNull to fix DB error messages about null values.

Use the bindValueNoNull for all QString variables that are used for
database access in ChannelUtil::CreateChannel? and ChannelUtil::UpdateChannel?.
Remove existing code to check for null because bindValueNoNull is now used.

Refs #13420