Setting the Relation

Ok, but how do we actually set the relation? How do we say "this StarshipPart belongs to this Starship"? So far, we've been working in AppFixtures with Foundry. We'll come back to Foundry in a bit, but let's go old school for a minute to see how this all works.

Start with new Starship()... then I'll paste in some code to set the required properties. Then add $manager->persist($starship). Next create a new StarshipPart and just like before, I'll paste code to fill in the properties. Then make sure this saves with $manager->persist($part), and finally, $manager->flush(). Foundry usually calls persist() and flush() for us. But since we're in manual mode, we need to do it ourselves.

We have a Starship and a StarshipPart, but they're not related yet. Pff, try to load the fixtures anyway. Head over to your terminal and run:

symfony console doctrine:fixtures:load

Rutro:

starship_id cannot be null on the starship_part table.

Why is that column required? In StarshipPart the starship property has a ManyToOne and a JoinColumn attribute. This lets us control the foreign key column: nullable: false means that every StarshipPart must belong to a Starship.

Assigning the Part to the Starship

So how do we say that this part belongs to this Starship? The answer is beautifully simple. Anywhere before flush(), say $part->setStarship($starship). That's it. With Doctrine, we're not setting some starship_id property or even passing an ID, like $starship->getId(). Nope! We set objects. Doctrine handles the boring details of inserting this: first saving the Starship, then using its new id to set the starship_id column on the starship_part table.

Smart!

Try the fixtures again:

symfony console doctrine:fixtures:load

Error-free! Check things out:

symfony console doctrine:query:sql 'SELECT * FROM starship_part'

Et voila! There's our single part, happily linked to Starship id 75. Look that up:

symfony console doctrine:query:sql 'SELECT * FROM starship WHERE id = 75'

There it is: Starship id 75 has a StarshipPart id 1. We're awesome!

Doctrine: work with Objects, Not IDs

Here's the takeaway: with Doctrine relations, you're in the world of objects. Forget about IDs. Doctrine takes care of that part for you. You set the object, and Doctrine does the rest.

But ugh, this is a lot of work in AppFixtures to create a single Starship and a single StarshipPart. So next, let's bring Foundry back to create a fleet of ships a pile of parts and link them all in one fell swoop. This is where Foundry really shines.