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Adding Items to a Collection Property


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Use the docs to check out the User with id=2. When we read a resource, we can decide to expose any property - and a property that holds a collection, like cheeseListings, is no different. We exposed that property by adding @Groups("user:read") above it. And because this holds a collection of related objects, we can also decide whether the cheeseListings property should be exposed as an array of IRI strings or as an array of embedded objects, by adding this same group to at least one property inside CheeseListing itself.

Great. New challenge! We can read the cheeseListings property on User... but could we also modify this property?

For example, well, it's a bit of a strange example, but let's pretend that an admin wants to be able to edit a User and make them the owner of some existing CheeseListing objects in the system. You can already do this by editing a CheeseListing and changing its owner. But could we also do it by editing a User and passing a cheeseListings property?

Actually, let's get even a bit crazier! I want to be able to create a new User and specify one or more cheese listings that this User should own... all in one request.

Making cheeseListings Modifiable

Right now, the cheeseListings property is not modifiable. The reason is simple: that property only has the read group. Cool! I'll make that group an array and add user:write.

186 lines | src/Entity/User.php
// ... lines 1 - 22
class User implements UserInterface
// ... lines 25 - 58
// ... line 60
* @Groups({"user:read", "user:write"})
private $cheeseListings;
// ... lines 64 - 184

Now, go back, refresh the docs and look at the POST operation: we do have a cheeseListings property. Let's do this! Start with the boring user info: email, password doesn't matter and username. For cheeseListings, this needs to be an array... because this property holds an array. Inside, add just one item - an IRI - /api/cheeses/1.

In a perfect world, this will create a new User and then go fetch the CheeseListing with id 1 and change it to be owned by this user. Deep breath. Execute!

It worked? I mean, it worked! A 201 status code: it created the new User and that User now owns this CheeseListing! Wait a second... how did that work?

Adder and Remover Methods for Collections

Check it out: we understand how email, password and username are handled: when we POST, the serializer will call setEmail(). In this case, we're sending a cheeseListings field... but if we go look for setCheeseListings(), it doesn't exist!

Instead, search for addCheeseListing(). Ahhh. The make:entity command is smart: when it generates a collection relationship like this, instead of generating a setCheeseListings() method, it generates addCheeseListing() and removeCheeseListing(). And the serializer is smart enough to use those! It sees the one CheeseListing IRI we're sending, queries the database for that object, calls addCheeseListing() and passes it as an argument.

The whole reason make:entity generates the adder - instead of just setCheeseListings() - is that it lets us do things when a cheese listing is added or removed. And that is key! Check it out: inside the generated code, it calls $cheeseListing->setOwner($this). That is the reason why the owner changed to the new user, for this CheeseListing with id=1. Then... everything just saves!

Next: when we're creating or editing a user, instead of reassigning an existing CheeseListing to a new owner, let's make it possible to create totally new cheese listings. Yep, we're getting crazy! But this will let us learn even more about how the serializer thinks and works.