Hydrating pivot relations with additional columns?

[mk-conn]

I was not able to sync relations where additional pivot columns are used. E.g. I want to set the current authenticated user (fields 'created_by', 'updated_by'). I tried to fiddle around with the hydrateRelated in the hydrator but did not come any far... Is there some example on how to do this?

[lindyhopchris]

Hi @mk-conn

You can implement a custom method - if your relationship is called "comment", add the hydrateRelatedComment() method on your hydrator and it will be invoked instead of the hydrator working out what to do. You'll receive the relationship and the record (model) as the two arguments. The relationship is an instance of CloudCreativity\JsonApi\Contracts\Object\RelationshipInterface.

Let me know if this works. It'd also be great if you could share your code as to what you put in the method. The next version is going to have some changes to the hydrator so it'd be really handy if I added a test for what you're doing as I think your use case sounds like it is definitely something the package needs to support.

[mk-conn]

Okay, I'll try to get something working...

[lindyhopchris]

Note to myself. With the new relationship adapters in 1.x-dev, adding pivot data would be possible.

Something like in the JSON API adapter:

public function comments()
{
    return $this->hasMany()->withPivotData(['foo' => 'bar']);
}

(or some other method name)

[tembra]

Hello @lindyhopchris

I read your note to yourself 😆

Now that adding pivot data would be possible, how is the easiest way I can fill these columns by myself while we do not reach 1.1.0 ML? I mean: which function do you suggest to override (if it is even possible with given ones) ?

Another question is how do you pretend to send these pivot data? I'm planing to work with a meta member inside the relationship? What do you think so?

Thank you.

EDIT: Remembering that I need to fill these columns while saving (create/update) and also retrieve them while reading.

EDIT 2: I'm wondering if wouldn't be better for now to create a resource and a model for the third table (e.g. role_user) and treat as two one-to-many relationships. Of course this resource should not have routes registered.

[lindyhopchris]

@tembra sorry for slow reply.

Easiest way to do this at the moment is to extend the relationship class - e.g. the LaravelJsonApi\Eloquent\HasMany relationship and look at the protected methods in that.

I am not anticipating supporting sending pivot data from the client, because that is not supported by the spec. This feature will be for populating server-side calculated pivot data. If you need the client to supply attributes, you should represent the pivot as a resource in your API. I.e. an intermediary resource between two other resources.

So yes, your Edit 2 is correct!

[fibis]

As one of the options is to represent the pivot table as a resource in the API, is there the possibility to add a resource without an Eloquent model but a database table?

[lindyhopchris]

Yes this can totally be done! The thing to bear in mind is the encoder maps objects to JSON API schemas using the object class. So you can't just pass in "raw" database results from a query builder.

So you'll need to wrap the row of the pivot database table in a specific class - then map the wrapper class to a JSON API schema in your API's config. This is effectively a presenter approach. Let me know if you've got any questions about this.

[crabmusket]

It should be possible to do this using a custom controller method too, right? I don't know exactly how to write such a method, but I'll be giving it a go soon.

Also, it looks like Laravel has a withPivotValue method introduced in 5.6 which would allow you to set a 'default' value at the Eloquent level. This looks really handy.

[lindyhopchris]

Closing as the new package laravel-json-api/laravel has support for pivot tables on belongs-to-many relations:
https://laraveljsonapi.io/docs/1.0/schemas/relationships.html#belongs-to-many

And for filtering using values on the pivot table:
https://laraveljsonapi.io/docs/1.0/schemas/filters.html#wherepivot