If I understand you correctly, you want to define a Perl object that doesn't directly relate to one table but to column from multiple tables? DBIC result objects always represent exactly one table with all its columns, primary and unique keys and relationships. What you want is a 'business' layer on top of that which you can define however you like, for example with Moose, that uses the DBIC objects so you don't have to deal with SQL.
Am 2012-06-15 15:06, schrieb Alex Erzin: > Hm...You revert idea of ORM ;) > > "extend one table class (called resultsource/resultset in DBIC) to form > another table class" - I not need a _table_class_ at all. > I need just a Host object with related properties regardless of one or two or > three tables I need to represent my object in RDBMS. > In reality i need more extended hierarhy of classes, but here i try to find > elegant solution only for two objects where one is inherited from another. > And one of the ways is to use two tables where one table is represent common > fields for both classes and another table represents fields only > specific for inherited class. And when i need to create one more inherited > class i need simple to add new fields in new table - that's all. > This in theory (or in Java ;) > > In other words, is it possible in Perl do something like in Hibernate in Java > or no? > And if possible - how to do this? > > PS. I already have mentioned that have developed such subsystem some years > ago, but it was commercial project and i cannot use that solution in my > current projects. > I think that exists some free solution... seems to me i'm wrong with it. > > > > 15.06.2012, 15:53, "Alexander Hartmaier" <[email protected]>: >> Hi Alex, >> there is no such thing as inheritance in an RDBMS, so why whould an ORM >> extend one table class (called resultsource/resultset in DBIC) to form >> another table class? >> To get you started it's usually the easiest to let dbicdump [1] create >> all the DBIC classes and look at what it generated. >> Also the glossary [2] is a great thing to read before the rest of the >> docs to know which terms the docs use for the various components. >> >> [1] https://metacpan.org/module/dbicdump >> [2] https://metacpan.org/module/DBIx::Class::Manual::Glossary >> >> BR Alex >> >> Am 2012-06-15 10:30, schrieb Alex Erzin: >> >>> I'm confused with "package Host; extends 'Base';" >>> I expect "extends 'Target'", not 'Base'. Is it correct? >>> >>> 15.06.2012, 12:06, "Hailin Hu" <[email protected]>: >>>> I have no idea about "standard" solution, but another idea for reference >>>> :) >>>> >>>> Package Base; >>>> use base 'DBIx::Class::Core'; >>>> >>>> # parents' name should be a defined has_one or belong_to relationship >>>> has 'parents' => ( >>>> is => 'rw', >>>> isa => 'ArrayRef[Str]', >>>> builder => _build_parents, >>>> ); >>>> >>>> sub inflate_result { >>>> my $self = shift; >>>> my $ret = $self->next::method( @_ ); >>>> foreach my $relationship ( @{ $ret->parents } ) { >>>> my $parent = $ret->$relationship; >>>> my @columns = ... # @columns_in_$parent - @column_in_$ret >>>> foreach my $column ( @columns ) { >>>> # stolen from DBIx::Class's source >>>> no strict 'refs'; >>>> no warnings 'redefine'; >>>> my $method = join '::', ref $ret, $column; >>>> *$method = Sub::Name::subname( $method, sub { >>>> return $ret->$parent->$column; >>>> }); >>>> } >>>> } >>>> } >>>> ... >>>> >>>> package Target; >>>> extends 'Base'; >>>> ... >>>> >>>> package Host; >>>> extends 'Base'; >>>> __PACKAGE__->belong_to('target' => 'Target', 'target_id'); >>>> sub _build_parents {[qw/target/]} >>>> ... >>>> >>>> so just declare the attribute 'parents' in subclass is ok. >>>> the task is not typical for me, but interesting. >>>> >>>> On Fri, Jun 15, 2012 at 3:59 PM, Alex Erzin <[email protected]> wrote: >>>>> Yes, in some cases you are right, but you are saying about "long >>>>> inheritance chains" and other cases where inheritance is not enought >>>>> flexible, >>>>> but i say about just one case in one place where inheritance is >>>>> preferred for me, and i try to find solution _how_ to implement >>>>> inheritance, but not about _why_not_ :) >>>>> >>>>> 15.06.2012, 10:43, "Ben Tilly" <[email protected]>: >>>>>> The benefits of OOP are mostly in information hiding. >>>>>> >>>>>> If you're creating a bunch of long inheritance chains, you're probably >>>>>> doing OOP poorly. Composition is preferred. And maps *much* more >>>>>> naturally onto a relational database. >>>>>> >>>>>> On Thu, Jun 14, 2012 at 11:37 PM, Alex Erzin <[email protected]> >>>>>> wrote: >>>>>>> Hm... it really works, but where are benefits of OOP? ;) >>>>>>> There is no inheritance at all, and to access parent's properties I >>>>>>> should call parent directly, so inheritance just replaced with >>>>>>> incapsulation, and it's no one what i try to find. >>>>>>> >>>>>>> Some years ago we have implemented inheritance in ORM in some >>>>>>> commercial project in Perl, later I have swithed to java and have found >>>>>>> Hibernate it really cool with ORM. >>>>>>> But now I have returned to Perl and I think that DBIx::Class can >>>>>>> help me with ORM, but right now i'm confused that cannot find >>>>>>> "standard" solution for typical task. >>>>>>> >>>>>>> 15.06.2012, 10:25, "Hailin Hu" <[email protected]>: >>>>>>>> Is it acceptable like something below >>>>>>>> >>>>>>>> package Target; >>>>>>>> ... >>>>>>>> package Host; >>>>>>>> ... >>>>>>>> __PACKAGE__->belong_to('target' => 'Target', 'target_id'); >>>>>>>> sub column_only_exists_in_target { >>>>>>>> my $self = shift; >>>>>>>> return $self->target->column_only_exists_in_target; >>>>>>>> } >>>>>>>> >>>>>>>> well, it is not a good solution, but it could work, I think :) >>>>>>>> >>>>>>>> On Fri, Jun 15, 2012 at 3:04 PM, Alex Erzin <[email protected]> >>>>>>>> wrote: >>>>>>>>> Hello, >>>>>>>>> >>>>>>>>> I need to implement table-per-class inheritance, as it simple >>>>>>>>> made in Hibernate in Java (more details can be found here >>>>>>>>> http://docs.jboss.org/hibernate/orm/4.1/manual/en-US/html/ch10.html#inheritance-tablepersubclass), >>>>>>>>> but cannot find right way how to do it in DBIx::Class. >>>>>>>>> >>>>>>>>> For example, I have two objects: Target (with properties ID, >>>>>>>>> Description) and Host (ID, Hostname, IP), Host inherited from Target, >>>>>>>>> and on table-level there are two tables Host and Target, joined by ID >>>>>>>>> field. >>>>>>>>> >>>>>>>>> CREATE TABLE `mydb`.`target` ( >>>>>>>>> `target_id` INT NOT NULL , >>>>>>>>> `description` VARCHAR(45) NULL , >>>>>>>>> PRIMARY KEY (`target_id`) ) >>>>>>>>> >>>>>>>>> CREATE TABLE `mydb`.`host` ( >>>>>>>>> `target_id` INT NOT NULL , >>>>>>>>> `hostname` VARCHAR(45) NULL , >>>>>>>>> `ip` VARCHAR(45) NULL , >>>>>>>>> PRIMARY KEY (`target_id`) , >>>>>>>>> CONSTRAINT `fk_host_target` >>>>>>>>> FOREIGN KEY (`target_id` ) >>>>>>>>> REFERENCES `mydb`.`target` (`target_id` ) >>>>>>>>> ) >>>>>>>>> >>>>>>>>> How to implemeng there classes Target and Host, so it possible to >>>>>>>>> write >>>>>>>>> >>>>>>>>> print $target->id(), $targer->description() >>>>>>>>> print $host->id(), $host->description(), $host->hostname(), >>>>>>>>> $host->ip() >>>>>>>>> >>>>>>>>> ? >>>>>>>>> >>>>>>>>> I have no ideas how to implement inheritance, and all my >>>>>>>>> experiments are failed - from Host i cannot get access to parent >>>>>>>>> properties like description. >>>>>>>>> Could you help me please (with examples)? >>>>>>>>> >>>>>>>>> Thanks. >>>>>>>>> >>>>>>>>> -- >>>>>>>>> eaa@ >>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>> 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/[email protected] >>>>>>>> _______________________________________________ >>>>>>>> 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/[email protected] >>>>>>> -- >>>>>>> eaa@ >>>>>>> >>>>>>> _______________________________________________ >>>>>>> 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/[email protected] >>>>>> _______________________________________________ >>>>>> 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/[email protected] >>>>> -- >>>>> eaa@ >>>>> >>>>> _______________________________________________ >>>>> 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/[email protected] >>>> _______________________________________________ >>>> 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/[email protected] >> *"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"* >> T-Systems Austria GesmbH Rennweg 97-99, 1030 Wien >> Handelsgericht Wien, FN 79340b >> *"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"* >> Notice: This e-mail contains information that is confidential and may be >> privileged. >> If you are not the intended recipient, please notify the sender and then >> delete this e-mail immediately. >> *"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"* >> >> _______________________________________________ >> 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/[email protected] > -- > Cheers, Alex _______________________________________________ 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/[email protected]
