Slides for the talk future-of-dbix-class at npw-2009
The future of
DBIx::Class
-
Matt S Trout
-
Catalyst
DBIx::Class
Moose
-
Shadowcat Systems Limited
http://shadowcat.co.uk/
-
North West
England
-
Web Development
Consultancy
-
international
client base
-
"mst
doesn't
sleep"
-
no, I just work
on too many
time zones ...
-
-
Conference
Driven Development
-
Conference
Driven Design
-
works if they
tell me they
accepted
the talk ...
-
-
The past of
DBIx::Class
-
Class::DBI
-
the "classic"
perl ORM
-
Schwern
-
Tony
Bowden
-
Class::DBI::Sweet
-
Christian
Hansen
-
ActiveRecord
:include
-
"you can't
do that in
Class::DBI"
-
two days
later ...
-
fighting the
superclass
-
backwards
compatibility
-
bugwards
compatibility
-
unrefactorable
-
new research
project
-
DBIx::Class
-
start from
scratch
-
Class::DBI
test suite
-
composite
keys
-
join and
prefetch
-
component
system
via MI
-
very
experimental
-
then people
deployed it!
-
they deployed
our trunk to
production!
-
AAARGH!
-
stable
release
cycle
-
never
finished
researching
-
lots of
design
mistakes
-
lots of
new tools
available
-
time for
a rethink
-
this one -is-
refactorable
-
-
The present of
DBIx::Class
-
What did we
get right?
-
making
everything
objects
-
Schema
object
-
multiple
connections
-
central
object for
schema +
connection
-
Storage
and Cursor
objects
-
hides away
backend
specifics
-
auto-increment
limit syntaxes
DBD weirdnesses
-
(even DBI)
-
ResultSource
object
-
table/view
metadata
-
not tied to
the class
-
relationships
-
near side
far side
join condition
-
no single
column
assumptions
for keys
-
Result
Class
-
inflate_result
-
minimal
protocol
-
don't even
need objects
-
ResultSet
-
virtual
view
-
lazy
persistence
backed
collection
-
pure
functional
-
(sort of)
-
chainable
updatable
cacheable
-
EXTENSIBLE
-
-
digression
-
ResultSets
fucking
rock
-
ResultSets
were an
accident
-
trying to
factor things
out cleanly
-
need an 'aha'
moment to
use them right
-
I don't like
aha moments
-
they remind
me of failing
to learn lisp
-
they remind
me of failing
to learn monads
-
they remind
me of failing
to learn git
-
"learning this
will make you
a better
programmer"
-
great
-
what about
being done and
down the pub?
-
Result Class
vs.
ResultSource
object
-
inflate_column
vs.
add_relationship
-
list context
vs.
scalar context
-
search() args
vs.
find() args
-
aha moments
indicate
conceptual
inconsistency
-
sometimes that means
UR CONCEPTUALISIN
IT COMPLETELY WRONG
-
(so you should
still learn lisp
for that aha)
-
usually it just
means the UI
is retarded
-
(see git)
-
essential
vs.
implementation
complexity
-
better
understanding
-
better
conceptualisation
-
better
implementation
-
DBIx::Class
sucks
-
because it
raised our
expectations
-
understand
(ab)use
hate
improve
-
-
The present of
DBIx::Class
-
What did we
get wrong?
-
... most
things ...
-
lots of
details
-
filter
vs.
single
accessor
-
find() deflates,
search() doesn't
-
connection
attached to
schema
instance
-
details?
-
underlying
design
mistakes
-
persistent
vs.
non persistent
-
why should
"in the same
database"
be special?
-
query
handling
-
SQL::Abstract
AST has too
much DWIM
-
too much
DWIM?!
-
hard to
introspect
-
can't do
inference
-
objects know
too much
-
->insert
-
why should it
care it's
persisted?
-
$rs->next
-
stupid
stupid
STUPID
-
implicit
iterators
are BAD
-
each %hash
anyone?
-
(even 5.8.8's
Data::Dumper
gets it wrong)
-
ORM
-
O/R
Mapper
-
where's the
mapper?
-
one class
<->
one table
-
one class
<->
one view
-
we can fake
it with
delegation
-
search() doesn't
understand
that though
-
-
so, are we
fucked?
-
NO
-
(because we
didn't get to
the pub in time
to pull ...)
-
designed
to be
refactored
-
lots of
tests
-
(CDBICompat
has better
tests than
Class::DBI)
-
rebuild
refactor
re-use
rebase
-
-
The future of
DBIx::Class
-
persistence
backend
-
class CD;
has id ...
has title ...
has year ...
-
class MusicDB;
has cds => (
isa => HashMap[CD, over => 'id'],
...
);
-
my $music = MusicDB->new;
my $cd = $music->cds->add({
title => 'Morning Rain'
});
is($cd, $music->cds->{$cd->id});
-
my $db_schema = schema {
table cds {
column id auto_increment;
column title ...
}
}
-
my $store = Data::Store->new(
driver => 'DBI', # DBIx::Class :)
schema => $db_schema,
);
-
# this is a complete guess
my $music = $store->connect(
dsn => $dsn
)->associate(
'MusicDB',
cds => 'cds'
);
-
what's my
point?
-
uniform
data APIs
-
a collection is
a collection is
a collection ...
-
perl array
directory
database table
-
we shouldn't
care about what
data -is-
-
we should care
about what it
can -do-
-
Data::CapabilityBased
-
capability?
-
a role with
a default
implementation
-
and a
validation
test suite
-
Data::Collection::Capability::Mappable
-
$coll->map(sub {
...
});
-
$coll->map_by('title');
-
method map_by ($attr) {
$self->map(sub ($x) {
$x->$attr;
});
}
-
class DBIx::Class::ResultSet;
method map_by ($attr) {
if ($self->_has_relationship($attr)) {
return $self->search_related($attr);
}
...
}
-
semantic
queries
-
use Data::Query qw(expr);
$coll->grep(expr {
$_->name eq 'Bob'
});
-
array?
grep { $_->name eq 'Bob' } @array
-
resultset?
WHERE name = 'Bob'
-
SQL::Abstract 2
provides an
explicit AST
-
Data::Query
backend generates
to the AST
-
streams
-
my $stream = $rs->as_stream;
while (my $obj = $stream->next) {
...
}
-
compatibility?
-
class DBIx::Class::ResultSet;
method next {
$self->_implicit_stream
->next;
}
-
I wish I
had time
to tell
you about
-
observability
projection
caching
partitioning
-
async streams
complex mappings
flush strategies
transactions
-
but I
don't
-
Data::CapabilityBased
will go to CPAN when
I get an internet
connection that works
-
discussion will
happen on the
dbix-class list
and channel
-
these slides
will be on
http://shadowcat.co.uk/
-
Any
Questions?
-
Thank
You
-
irc.perl.org #dbix-class
http://lists.scsys.co.uk/
these slides will be on
http://shadowcat.co.uk/