[mythtv-users] Can't seem to delete channels

[Stephen Worthington]

On Sat, 31 Jul 2021 23:38:47 -0400, you wrote:

>I think you're basically correct.  Having now looked at this more
>carefully, it appears two things are true:
>
>(a) Deselecting a channel in the sqlite DB -does- in fact stop it being
>downloaded by tv_grab_zz_sdjson_sqlite---those channels are now showing
>"NO DATA" out past a certain horizon in the mythweb listings page,
>whereas others are showing data, and looking at the raw XML data
>downloaded (snatched from /tmp during a grabber run) shows that the ones
>I deselected are missing from the <channel> ... </channel> block at the
>beginning but were present in the one I saved from my very first run. [1]
>
>However, deselection may actually be a bad idea---the "CHANNEL SELECTION"
>section of the tv_grab_zz_sdjson_sqlite manpage seems to be one large
>caveat about how confusion between "channel" and "station" might cause
>the wrong thing to happen if the provider starts rearranging things.
>
>So maybe I'll leave everything selected and just set channels invisible
>on the mysql side, though that involves downloading about twice as much
>data and twice as much mfdb work to do for a bunch of channels which are
>marked invisible and hence will never be scheduled.
>
>(b) There's no communications channel from the grabber to myth to tell
>myth that a channel has been deselected.  However, setting it invisible
>(not, as I started out in my Subject: line, trying to delete it, as the
>Channel Editor [2] does) does in fact do the right thing, and that's how
>I did it in my ancient installation---invisibility dropped it from both
>scheduling and display.  So I'll probably just do that via direct DB
>manipulation or perhaps an API call---I did before & after mysql DB
>dumps after setting a channel invisible, and it clearly only modified
>its visibility in the channel table.  (We're talking hundreds of
>channels here, so there's no way I'm going to be doing this by hand.)
>
>[1] I wish there was some easy way to tell tv_grab_zz_sdjson_sqlite to
>preserve the original file.  I suspect I could use one of the debugging
>flags to download it a second time into a file and leave the file alone,
>but that's pretty inefficient, and racy too.  Or I can make something
>that watches for the file to appear in /tmp and copies it once it hasn't
>changed for a little while and/or ends in "</tv>", since it doesn't get
>deleted for many minutes while mfdb runs. :)  If there's a straightforward
>way to do this, I can't find it in the manpage.
>
>[2] It is super-confusing that there are -three- "channel editors"---
>the wiki mentions a perl script, the frontend, and mythtv-setup.
>The one I've been talking about is the latter.

It occurred to me while reading this that channels you are not
downloading EPG for do not have data in the program table, and that is
a condition that you can use SQL to find.  So you should be able to do
some SQL that will make invisible all channels that do not have EPG
data after a given date.