[Dbix-class] Filtering out inactive records
Vladimir Melnik
v.melnik at uplink.ua
Thu Feb 9 12:43:18 GMT 2017
Yes, that seems to be working fine, thank you very much!
foreach my $movie ($actor->movies->filter_valid(source_alias => 'me')->filter_valid(source_alias => 'movie')) { ... }
Makes:
SELECT movie.id, movie.valid_since, movie.valid_till, movie.removed, movie.name, movie.movie_type_id, movie.provider FROM actor_x_movie me JOIN movie movie ON movie.id = me.movie_id WHERE ( ( ( ( movie.valid_till IS NULL OR movie.valid_till > ? ) AND ( me.valid_till > ? OR me.valid_till IS NULL ) ) AND movie.removed IS NULL AND movie.valid_since <= ? AND me.actor_id = ? AND me.removed IS NULL AND me.valid_since <= ? ) ): '2017-02-08 14:15:21', '2017-02-08 14:15:21', '2017-02-08 14:15:21', '2', '2017-02-08 14:15:21'
Thanks a lot!
On Thu, Feb 09, 2017 at 03:29:23PM +0300, Dmitry L. wrote:
> Sorry.
>
> my $movie = $actor->movie
> ->filter_valid() # for actor_x_movie
> ->filter_valid('movie') # for movie
> ->first;
>
> On 9 February 2017 at 15:28, Dmitry L. <dim0xff at gmail.com> wrote:
> > You can pass source alias to filter_valid like
> > my $movie =
> > $actor->movie->filter_valid->first;
> > ->filter_valid # for me
> > ->filter_valid()
> >
> > But I'd prefer views
> >
> > On 9 February 2017 at 15:17, Vladimir Melnik <v.melnik at uplink.ua> wrote:
> >> Wow, thank you very much! It works great.
> >>
> >> Do you have any suggestions on how to filter out the "inactive" records from the "actor_x_movie" table?
> >>
> >> Thanks!
> >>
> >> On Thu, Feb 09, 2017 at 12:05:29PM +0000, Colin Newell wrote:
> >>> The general ambiguity problem is easily solvable, what you need is the
> >>> 'current_source_alias'. That allows you to disambiguate your field
> >>> references and it works perfectly in the chained searches.
> >>>
> >>> http://search.cpan.org/~ribasushi/DBIx-Class-0.082840/lib/DBIx/Class/ResultSet.pm#current_source_alias
> >>>
> >>>
> >>> Colin.
> >>>
> >>> On 9 February 2017 at 11:55, Vladimir Melnik <v.melnik at uplink.ua> wrote:
> >>> > Hello,
> >>> >
> >>> > Lots of thanks to the founders and maintainers for such a useful and handy framework! :)
> >>> >
> >>> > The database schema of the project I'm currently working on implies presence of 3 additional fields in each table:
> >>> > `valid_since` datetime NOT NULL,
> >>> > `valid_till` datetime DEFAULT NULL,
> >>> > `removed` datetime DEFAULT NULL
> >>> >
> >>> > Their names are pretty self-descriptive: most of queries (not all, but most of them) should select only the rows that are "valid" (valid_since <= NOW() AND valid_till > NOW()) and aren't "removed" (removed IS NULL).
> >>> >
> >>> > I decided to create a package that is called ***::Schema::DefaultResultSet with the following method:
> >>> >
> >>> > method filter_valid (
> >>> > DateTime $now? = DateTime->now
> >>> > ) {
> >>> > $self->search(
> >>> > {
> >>> > -and => [
> >>> > { removed => { '=' => undef } },
> >>> > { valid_since => { '<=' => $now } },
> >>> > {
> >>> > -or => [
> >>> > { valid_till => { '=' => undef } },
> >>> > { valid_till => { '>' => $now } }
> >>> > ]
> >>> > }
> >>> > ]
> >>> > }
> >>> > );
> >>> > }
> >>> >
> >>> > It lets me to do call the filter_valid method for filtering out the "disabled" records for each result. For example:
> >>> > $db_schema->resultset("Actor")->search({ name => 'Vasya' })->filter_valid;
> >>> >
> >>> > It works fine until I'm not trying to implement it for many-to-many relations. There are 2 problems I'm facing.
> >>> >
> >>> > (1) "Column 'valid_till' in where clause is ambiguous"
> >>> >
> >>> > There's the "actor_x_movie" table which is being used for building the many-to-many relation between the "actor" and "movie" tables. In the ***::Schema::Result::Actor I've added the following:
> >>> >
> >>> > __PACKAGE__->many_to_many("movies" => "actor_x_movie", "movie");
> >>> >
> >>> > It works fine, so I can do the following:
> >>> > my $actor = $db_schema->resultset("Actor")->search({ name => 'Vasya' })->filter_valid->first;
> >>> > my $movie = $actor->movie->first;
> >>> > ...and it gives me the first result from the "movie" table that the first result of the "actor" table is related to. That's fine.
> >>> >
> >>> > The problem appears when I add the filter_valid:
> >>> > my $movie = $actor->movie->filter_valid->first;
> >>> >
> >>> > I'm getting the following exception:
> >>> > DBIx::Class::Storage::DBI::_dbh_execute(): DBI Exception: DBD::mysql::st execute failed: Column 'valid_till' in where clause is ambiguous [for Statement "SELECT movie.id, movie.valid_since, movie.valid_till, movie.removed, movie.name, movie.movie_type_id, movie.provider FROM actor_x_movie me JOIN movie movie ON movie.id = me.movie_id WHERE ( ( ( valid_till IS NULL OR valid_till > ? ) AND me.actor_id = ? AND removed IS NULL AND valid_since <= ? ) )" with ParamValues: 0='2017-02-08 12:38:02', 1=2, 2='2017-02-08 12:38:02']
> >>> >
> >>> > Is there a way to make DBIx::Class performing the "filter_valid" part _after_ performing the "movie" query? Without something like that:
> >>> > $my $movie = $actor->movie; $movie = $movie->filter_valid->first?
> >>> >
> >>> > (2) Filtering out the "disabled" records from the "actor_x_movie" table
> >>> >
> >>> > Can I make DBIx::Class calling the "filter_valid" method for the records of "actor_x_movie" too? Of corse, I can do something like that:
> >>> > __PACKAGE__->many_to_many("movies" => "actor_x_movie", "movie", {
> >>> > -and => [
> >>> > { removed => { '=' => undef } },
> >>> > { valid_since => { '<=' => \'NOW()' } },
> >>> > {
> >>> > -or => [
> >>> > { valid_till => { '=' => undef } },
> >>> > { valid_till => { '>' => \'NOW()' } }
> >>> > ]
> >>> > }
> >>> > ]
> >>> > } );
> >>> > ...but adding it for EACH many-to-many relation doesn't seem to be a good idea. :( Is there a way to call "filter_valid" for the "actor_x_movie" resultset when performing the many-to-many query?
> >>> >
> >>> > I'm considering using MySQL Views. Maybe I need to make a separate view for each table: valid_actor, valid_movie, valid_actor_x_movie and so on, but it won't be tidy. :( What would you suggest? Did you have to deal with similar problems? What practices are the best? I'll be very grateful for any hints and tips regarding this topic.
> >>> >
> >>> > Thanks!
> >>> >
> >>> > --
> >>> > V.Melnik
> >>> >
> >>> > _______________________________________________
> >>> > List: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/dbix-class
> >>> > IRC: irc.perl.org#dbix-class
> >>> > SVN: http://dev.catalyst.perl.org/repos/bast/DBIx-Class/
> >>> > Searchable Archive: http://www.grokbase.com/group/dbix-class@lists.scsys.co.uk
> >>>
> >>> _______________________________________________
> >>> List: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/dbix-class
> >>> IRC: irc.perl.org#dbix-class
> >>> SVN: http://dev.catalyst.perl.org/repos/bast/DBIx-Class/
> >>> Searchable Archive: http://www.grokbase.com/group/dbix-class@lists.scsys.co.uk
> >>
> >> --
> >> V.Melnik
> >>
> >> _______________________________________________
> >> List: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/dbix-class
> >> IRC: irc.perl.org#dbix-class
> >> SVN: http://dev.catalyst.perl.org/repos/bast/DBIx-Class/
> >> Searchable Archive: http://www.grokbase.com/group/dbix-class@lists.scsys.co.uk
> >
> >
> >
> > --
> > //wbr, Dmitry L.
>
>
>
> --
> //wbr, Dmitry L.
>
> _______________________________________________
> List: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/dbix-class
> IRC: irc.perl.org#dbix-class
> SVN: http://dev.catalyst.perl.org/repos/bast/DBIx-Class/
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--
V.Melnik
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