Re: HABTM/Linking table structure question

On Oct 27, 4:20 pm, Carlos Lavin <carloslavi...@gmail.com> wrote:
> It is "standard". However, CakePHP isn't built to manage multi-column PK's,
> always single columned
>
> 2010/10/27 Dan <dannyetdi...@gmail.com>
>
>
>
> > On Oct 27, 3:07 pm, cricket <zijn.digi...@gmail.com> wrote:
> > > On Wed, Oct 27, 2010 at 8:07 AM, Dan <dannyetdi...@gmail.com> wrote:
> > > > Structure:
>
> > > > Projects
> > > > - project_id
> > > > - project_name
>
> > > > Contacts
> > > > - contact_id
> > > > - contact_name
>
> > > > Contacts_Projects
> > > > - project_id
> > > > - contact_id
>
> > > > When reading the Cookbook, in a HABTM setting, I should add an ID
> > > > field to the Contacts_Projects table.
>
> > > That's not a requirement. But, if you find that you need to store
> > > extra information in the join table, it's recommended that you then
> > > add a primary key.
>
> > > > Wouldn't this field enable the
> > > > possibility of having duplicates?
>
> > > UNIQUE(project_id, contact_id);
>
> > > This creates an index. That's why a PK isn't absolutely necessary.
>
> > > > Or does the ID field only act as auto number, but the key is still
> > > > composed of project_id/contact_id?
>
> > > Sort of. The id column becomes the PK and you'd then have two indexes
> > > on the table. If you do add a PK, you should keep the unique index as
> > > that's what Cake will be using. However, Cake doesn't ever use
> > > multi-column PKs..
>
> > Okay, so if my linking table has a PK comprised of these two fields
> > (and no ID auto number field) should I remove the primary key and
> > replace it with an index?
>
> > My goal is to simply associate contacts to a project, thus each
> > model's PK. I don't need the ID field in that case right?
>
> > > that's what Cake will be using. However, Cake doesn't ever use
> > > multi-column PKs..
>
> > I always thought that having a multi-column PK was "standard" when
> > developing a DB?
>
> > Next, putting those associations to work :)
>
> > Check out the new CakePHP Questions sitehttp://cakeqs.organd help others
> > with their CakePHP related questions.
>
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>
> --
> -Carlos

Alright, put that to the test. I'm not getting the desired results
though:

5 SELECT `Project`.`project_id`, `Project`.`project_name` FROM
`tsdmgr_projects` AS `Project` WHERE `Project`.`project_id` = 1 LIMIT
1 1 1 1
6 SELECT `Contact`.`contact_id`, `Contact`.`contact_name`,
`ContactsProjects`.`project_id`, `ContactsProjects`.`contact_id` FROM
`tsdmgr_contacts` AS `Contact` JOIN `tsdmgr_contacts_projects` AS
`ContactsProjects` ON (`ContactsProjects`.`project_id` = 1 AND
`ContactsProjects`.`contact_id` = `Contact`.`contact_id`) 1 1 0

However, when I print the value of $this->data, I get this:

array(
"Project" => array(),
"Contact" => array()
)

Here's the model:

class Project extends AppModel {
var $name = 'Project';
var $primaryKey = 'project_id';

var $hasAndBelongsToMany = array(
'Contact' => array(
'className' => 'Contact',
'joinTable' => 'contacts_projects',
'foreignKey' => 'project_id',
'associationForeignKey' => 'contact_id',
'with' => 'ContactsProjects',
),
);
}

Controller bits:

$this->Project->id = $id;
$this->data = $this->Project->read()

View bits:

Debugger::dump($this->data);

If the two queries are run separately in Toad, they return one record
as they should (and seems to be indicated).

Check out the new CakePHP Questions site http://cakeqs.org and help others with their CakePHP related questions.

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