Best practice with many-to-many relationships id's

Hi everyone,

I have some doubts with the many-to-many tables id's (primary key). A many-to-many relationship is composed, according to the Laravel documentation, of two models and three tables. Each model has its corresponding table, and the intermediate table has as fields:

• Auto-incremental ID
• table1_id
• table2_id
• other_attributes ...

So far, all good. I have already used it a lot, accessing the fields with the helper 'pivot', and updating these with 'updateExistingPivot' and more.

The question I have is whether it is worth taking advantage of the ID of the intermediate table such as FK from attributes of other tables.

EXAMPLE:

In my application, I have these models:

• Machine
• Product
• Restriction

And these four tables:

• machines (id, name, ...) [Machine]
• products (id, name, ...) [Product]
• machine_products (id, machine_id, product_id, price) [without model]
• restrictions (id, machine_product_id, day, begin_hour, end_hour) [Restriction]

Given a specific machine and a product, there are N restrictions. One restriction belongs to one specific Machine and Product.

As you can see, I took advantage of the autoincremental ID (primary key of the intermediate table), to relate the restrictions. But in this way, working with Eloquent is a bit weird, like accessing a Restriction from a Machine / Product or vice versa, is not easy:

Restriction::find( Machine::find(1)->products()->first()->pivot->id );

If I would get a Product or Machine from a given Restriction, I would have to find the 'machine_id' and 'product_id' from the row with the 'machine_product_id' of the Restriction that I had.

Could you tell me or recommend the best way to solve this dilemma? Already modifying the tables, models, or whatever it takes.

Thank you.