[5.6] Add 'after' callback for model factories

[Indemnity83]

This PR implements the ability to add an after callback for model factories. The callback allows the user to define an action to be run after the model is created or made. A common use case for this behavior is to associate a user who is the owner of a group or team with the group or team, or to create an associated profile record for a new user model.

# TeamFactory.php

use Faker\Generator as Faker;

$factory->define(\App\Team::class, function (Faker $faker) {
    return [
        'name' => $faker->company,
        'slug' => $faker->slug(2),
        'owner_id' => function () {
            return factory(\App\User::class)->create()->id;
        },
    ];
});

$factory->after(\App\Team::class, 'create', function(\App\Team $team, Faker $faker) {
   $team->users()->attach($team->owner, ['role' => 'owner']);
});

If the action is omitted from the after function call, 'create' is assumed. Simplified ussage documentation snippet below:

After Callbacks

After callbacks allow you to define additional required logic to run after a model is created by a model factory. For example, your User model might have a required profile model, or you have a group or team model that has an owner but also requires the user to be added to a pivot table.

$factory->after(\App\Team::class, function(\App\Team $team, Faker $faker) {
     $team->users()->attach($team->owner, ['role' => 'owner']);
});

By default after callbacks are run after a model is created; if you want to run a callback after a make() call you can define the action the callback is to be run after as a third argument.

$factory->after(\App\User::class, 'make', function(\App\User $user, Faker $faker) {
     $profile = factory(\App\Profile::class)->make(['user_id' => $user->id]);
     $user->setRelation('profile', $profile);
});

[deleugpn]

I really like this, but I think it would be more relevant if you could show an use-case that cannot be achieved by Eloquent Created Event.

[browner12]

Yah, part of me feels this would be more appropriate to do in your Seeder class. IMO, the Factory class should be responsible only for generating it's single class, and additional logic should be done either with event handlers, as @deleugpn suggested, or in the corresponding Seeder.

[Indemnity83]

Hmm, maybe I'm just missing an existing opportunity here. I specifically ran into wanting to do this in testing where I needed to have a team, which has users and belongs to an owner. Existing functionality lets me define the owner of the team when I fake up a team; but that owner isn't a member of the team until they're also added to the pivot table. The team isn't valid without an owner_id. Similarly, the team isn't valid if the owner isn't also a member.

I don't think the Eloquent Created event applies to this situation, unless there is an intuitive way I'm missing to add this event listener during test setup?

I will concede that I can just attach the user to the team as the second line every time I create a new team. But I literally do it every test that has a team, they are directly coupled which is why I think this is appropriate.

[shadoWalker89]

+1
The way i'm doing it know is that i add methods to my test case like createUser(), createPaper(), create...
Which makes the test case feel gross.

I was thinking about making a PR that does the exact same thing :D hope it gets merged, this is really what i have been missing for my tests

[unstoppablecarl]

I like this a lot. The case that is missing is applying it conditionally like with a state. If it is something that should always be done when that model is created use events. I have room into this car where I want to make records and children for tests. The test code ends up with a ton of boilerplate. An API that let you bind after callbacks to a specific state would be awesome. Something like factory(User::class)->states('withPosts')

Shouldn't the action be 'created' ?

[deleugpn]

This is definitely a much cleaner solution than the current approach of having create{Something} methods in the test class. It is also preferred over Seeds since a lot of developers do prefer to have the seeding stage in their test separately.
And a good response to "why not events" is because you definitely wants to fire these relationship (attach/detach/sync) bindings only when using Factory and not when using Eloquent.

[unstoppablecarl]

I get the action names now. I would rather see methods named afterCreate afterMake

[taylorotwell]

Made some changes to this. Methods are afterMaking and afterCreating... also allow you to register multiple callbacks per model.

[unstoppablecarl]

I still want to see them per state :-\

[unstoppablecarl]

Would you accept a pr that allowed you to set them by state?

[antonkomarev]

This should be reflected in documentation.