Re: cascading update

[prev] [thread] [next] [Date index for 2005/04/08]

have you tried $cat->pid->update?


On Apr 8, 2005, at 1:08 PM, jldommer@xxxx.xxxxx.xxx wrote:

> Hi all,
>
> I've been working with cdbi for a couple of months now, but Ive been 
> using a lot of fairly inelegant code to mimic what my boss refers to 
> as 'cascading submit' with has_many.  What he means by 'cascading 
> sumbit' is that if I have a parent object with multiple children and I 
> change some of the fields in the child objects, I'd like to be able to 
> send these changes to the db by calling update on the parent so that I 
> don't have to call update on each of the individual children.  It has 
> to work in the opposite direction as well (i.e. if I have a child 
> object and change a field in the parent object, I'd like to update the 
> child instead of explicitly generating the parent to call update on, 
> which is what I do now).  Here is an example of what I'd like to have 
> work:
>
> I have a person (parent) object and a cat (child) object related like 
> this:
>
> TestOracle::Cat->has_a ( 'pid' => 'TestDBIsA::Person' );
> TestOracle::Person->has_many( 'cats' , 'TestDBIsA::Cat' => 'pid' );
>
> If I have retrieved my person from the database, I would like to be 
> able to update the cat's name like this:
> my @cats = $person->cats;
> my $cat = $cats[0];
> $cat->name('Mr. Whiskers');
>
> $person->update; # and I would like this to save the changes to cat.
>
> the call to update on $person does not save the change to the cat.  
> This isn't really a big issue going in this direction, since I can 
> loop over the array and call update every time (my current mimic), but 
> on larger arrays I'd like to just update once.  It becomes an bigger 
> issue when I try this:
>
> my $cat = TestOracle::Cat->retrieve(1);
> $cat->pid->firstname('Mike');
> $cat->update;
>
> Note that firstname is a column in my person class, not in cat.  pid 
> is the foreign key in cat to person.  The above code doesn't work, and 
> instead I have to explicitly create a person object to save the 
> changes that were made, which defeats the purpose of making the 
> changes to the parent via the child.  I've been searching the list 
> archive, but I haven't found anything that seems to deal with this.  
> Is there any way that I can do cascading sumbit other than with the 
> workarounds that I'm currently implementing?
>
> Jennifer Dommer
>