byterock

So today in the Moose-pen I am going to move onto something a little differtn and that is my Accessor 'links' attribute which I am going to cover with the 35_links.t test suite.

I did a quick review of the bits and pieces I had stubbed in so far and I notices I need a few thing. First had a look at my Accessor 'links' attribute and I will need a new type for that. So to get this new 'ArrayRefofLinks' type I just did what we have seen in a number of older posts, namely add in a 'use', a 'class_type' and a 'subtype' into my Types.pm, I will hold off on a coercion for now till I get a little deeper into my post. So that takes case of 'links'.

I also noticed that 'Links' attribute of my DAD now had the wrong type as well so that was change to the 'ArrayRefofLinks' type

Looking at my 'Database::Accessor::Link' class I have never liked this two attributes

 has to => (

        is       => 'rw',

        isa      => 'Str',

        required => 1,

        alias    => [qw( to_view view)]

    );


    has to_alias => (

        is    => 'rw',

        isa   => 'Str',

        alias =>[qw( alias view_alias)] 

    );

Now I need these because I know in SQL you can have a complicated join where you may want to join one of the tables you are joining on to a third table perhaps like this

 select person.name,agent.name

from person

left join on listing where person.listing_id = listing.id

left join on agent where listing.agent_id = agent.id

Now I think I can get rid of that very ugly 'to_alias' attribute by just changing the type of 'to' over to just an View class then I get both a 'name' and an optional 'alias' attribute. So now I have

    has to => (

        is    => 'rw',

        isa   => 'View',

        required => 1,

        alias =>[qw( to_view view) ],

        coerce   => 1,

    );

You will see that I added in the 'coerce' on the attribure. If I left that out then I would get an error like this;

Attribute (to) does not pass the type constraint 

because: Validation failed for 'View' with value HASH(0x559084c) (not isa 

Database::Accessor::View) at C

If I just passed a hash for this attribute. Always remember to do this it will save you great deal needless debugging.

Now to test this I will need a new hash like this

   my $in_hash = {

        view     => {name  => 'People'},

        elements => [{ name => 'first_name',

                                 view=>'People' },

                             { name => 'last_name',

                                view => 'People' },

                             { name => 'user_id',

                                view =>'People' },

                             { name=>'name',

                               view=>'country'} ],

                             

        links=>[{to        =>{name=>'country',

                              alias=>'a_country'},

                 type      =>'Left',

                 conditions =>[{left     =>{name =>'country_id',

                                          view =>'People'},

                              right    =>{name=>'id',

                                          view=>'a_country'},

                              operator =>'=',

                             }]},

                ],

  };

 

Here I unlike my 'conditions' attribute in my API I am not dropping the predicates/conditions param as I think it is a good Idea to leave it in. The coercion for this subtype is just like most of the others

coerce 'ArrayRefofLinks', from 'ArrayRef', via {   

     [ map { Database::Accessor::Link->new($_) } @$_ ];

};

but I think I will expand on that as there are many many time when there is just one join so lets try this

coerce 'ArrayRefofLinks', from 'ArrayRef', via {   

     [ map { Database::Accessor::Link->new($_) } @$_ ];

},

    from 'HashRef', via {

    return [Database::Accessor::Link->new($_) ];

};

and now I can do this

        links=>{to        =>{name=>'country',

                              alias=>'a_country'},

                 type      =>'Left',

                 conditions =>{left     =>{name =>'country_id',

                                          view =>'People'},

                              right    =>{name=>'id',

                                          view=>'a_country'},

                              operator =>'=',

                             }},

I am not going to bore you with all the testing details lets just say things came out Moosey OK.