[BioSQL-l] removing features from a sequence

[Hilmar Lapp]

Yeah I guess this is one of the gotcha's that deserve better 
documentation. The bioperl-db adaptors will not automatically 'sync' 
the database with an object. The reason is that there are too many 
flavors of what you could possibly want as a user, so instead of making 
decisions for you you need to make explicit what you want; however, 
doing so should be reasonably simple.

So here's what's going on and how you can fix it.

First, $dbseq->remove_SeqFeatures() is a Bio::SeqI method present for 
all SeqI objects, not just persistent ones. Except in a few cases where 
lazy loading is already implemented, methods from the native Bioperl 
API are not overridden for persistent objects; i.e., you can manipulate 
your persistent object to your heart's content and nothing will happen 
to the respective row(s) in the database. You need to say 
$dbseq->store() to let your changes take effect. But see below!

Second, $dbseq->store() will only store it; i.e., it will update the 
object and either update or insert all attached objects (like features, 
annotations, etc). If you want to delete attached objects then you need 
to do so explicitly by calling $pobj->remove().

For example, in your case:

	# ... find $dbseq ...
	# delete all features from the database
	# Note: I could use $dbseq->get_SeqFeatures() if I
	# wanted to keep the features on the in-memory object
	foreach my $pfeat ($dbseq->remove_SeqFeatures()) {
		$pfeat->remove();
	}
	# now $dbseq and the object in the db don't have features

Same thing for annotation. You can check out some of the sample closure 
implementations for merging objects provided in the scripts/biosql 
directory of bioperl-db, for instance freshen-annot.pl deletes all 
annotation (in the db) from the existing object.

Hth,

	-hilmar

On Oct 3, 2005, at 10:59 AM, Amit Indap wrote:

> Hi,
>
> I was trying to remove features for sequences stored in my BioSQL
> database. Once I run the code snippet below to remove sequence
> features, I tested to see if the features really had been removed by
> running a script that reterieves seq features from bioentries.
> Unfortunately, the features are still there. I'm still learning my
> around the Bio::DB API
>
> Here is my code to attempts to remove sequence features:
>
> foreach  (@accs) {
>
>     my $acc = $_;
>     my $adp = $dbadp->get_object_adaptor("Bio::SeqI");
>
>     my $seq = Bio::Seq->new(-accession_number => $acc,
> 			    -namespace => $namespace
> 			    );
>
>
>     my $dbseq = $adp->find_by_unique_key($seq);
>     warn $acc, "  not found in database $namespace" unless  $dbseq;
>
>     $dbseq->remove_SeqFeatures(); # remove seqfeatures
>
>     $dbseq->commit();
>     print LOG "removed all seq features for $acc\n";
> }
>
>
>
> --
> Amit Indap
> http://www.bscb.cornell.edu/Homepages/Amit_Indap/
>
> _______________________________________________
> BioSQL-l mailing list
> BioSQL-l at open-bio.org
> http://open-bio.org/mailman/listinfo/biosql-l
>
-- 
-------------------------------------------------------------
Hilmar Lapp                            email: lapp at gnf.org
GNF, San Diego, Ca. 92121              phone: +1-858-812-1757
-------------------------------------------------------------