[Deprecated] DMZ 1.5.3 (DataMapper OverZealous Edition)

[eluser]warrennz[/eluser]
@abbie
You would use the set_join_field() method.

I cannot answer you question as I am having an issue which I am guessing you will run into.

Using Abbie's example, and assuming it's a M:M relationship.

I realize this example may not make alot of sense in the context of machines and parts but just bare with me

If a machine had 2 identical parts, so in the database it had

Code:

------------------------------------------------
| id  | machine_id | part_id  | setting_1  | sett....
|-----|-----------------------|------------|------
| 1   | 1          | 2        |            |
| 2   | 1          | 2        |
----------------------------------

If you were to attempt to set some data in setting 1, 2 or 3 you would do

Code:

$m = new Machine();
$m->get_by_id(1);

$p = new Part()
$p->get_by_id(2)

$p->join_related_field($m,'setting_1','my custom setting');

This would essentially run a SQL Query along the lines of

UPDATE `machine_parts` SET `setting_1` = 'my custom setting' WHERE `machine_id` = 1 AND `part_id` = 2

As one mite have guessed, it will update BOTH the relation fields, which is not the desired effect.

Code:

------------------------------------------------
| id  | machine_id | part_id  | setting_1           | sett....
|-----|-----------------------|---------------------|------
| 1   | 1          | 2        | my custom setting   |
| 2   | 1          | 2        | my custom setting   |
------------------------------------------------------

Im at a total loss how to get around this one.. maybe I'm looking at this all wrong?

I was thinking the obvious fix was to use the id column to help single out the row I wanted EG

Code:

$p->where('machine_parts.id','2')->join_related_field($m,'setting_1','my custom setting');

But then I found myself wondering how to get that id?

When you save the new relationship via $p->save($m), does one of those objects store the specific relations ID?

Argh >< lost and confused on this one