Bill Moseley wrote:
I have a number of methods that start something like this:
sub view : Local Args(1) {
my ( $self, $c, $id ) = @_;
my $obj = $c->model( 'DB::Foo' )->find( $id )
|| return $c->res->status( 404 );
If $id is not valid then I might, as in that example, return with a
404 status.
Of course, if $id is suppose to be an integer and a non-integer or an
integer out of range is provided then the the database will throw an
exception, which I want to prevent. I want valid ids to return an
object and *anything* else to return undef before hitting the database.
This is pretty low-level validation -- just validating primary key.
For more complex validation I use a form validation module.
Obviously, I could do something like
return $c->res->status(404) unless $c->model('DB::Foo')->is_valid_id(
$id )
in every method, but that's not very DRY.
What I've done in the past is override the find() or search() method
in my model base class so that whatever $id is passed it is
validated. Specific model classes can override the is_valid_id()
method if they use keys that are not a common key format (i.e.
different integer range or non-integer key).
What's you approach to validating that $id in situations like this
where there's a single id?
Do you just let the database throw the exception? I prefer to return
404s for invalid ids, regardless of their format (and likewise for ids
that point to valid object, but are not owned by the current user
instead of a 403).
We did this sort of thing until we started to use chained actions.
Now we validate once at the start of the chain e.g.
sub start : Chained('/') CaptureArgs(0) {
my ( $self, $c ) = @_;
# your validation here
my $obj = $c->model( 'DB::Foo' )->find( $id )
|| return $c->res->status( 404 );
$c->stash->{obj} = $obj;
return 1;
}
sub view : Chained('start') Args(0) {
my ( $self, $c ) = @_;
# do something with $c->stash->{obj}
return 1;
}
until we did this we had boilerplate validation at the top of all the
local actions.
Iain.
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