Issue with MorphTo Relation: Call to a member function resource() on null

[mrsuarezg]

Laravel Rest Api Version

2.8.7

Laravel Version

11.30

PHP Version

8.3

Database Driver & Version

No response

Description

I am encountering an issue with the implementation of polymorphic relations (MorphTo) in the library. Following the documentation's guidelines, I configured my model and resource as instructed, but the implementation fails with a 500 Internal Server Error.

Observed Behavior
The API fails with the following error:

Call to a member function resource() on null

Upon debugging with Laravel Telescope, I traced the error to this line:

$relationResource = $relationConcrete->resource();

It seems the $relationConcrete object is null when resolving the physicalPeople or moralPeople relations.

Expected Behavior
The MorphTo relations (physicalPeople and moralPeople) should resolve correctly and return the associated Resource class (PhysicalPeopleResource or MoralPeopleResource), depending on the personable_type in the model.

Additional Context
If necessary, I can provide further debugging logs or a minimal reproducible example. Please let me know how to proceed or if additional information is required.

Thank you for your help! 😊

As a note in the first versions of the library when it was allowed to declare the polymorphic relationship with an array of Resources it was perfectly functional.

Steps To Reproduce

1. Configure the model as shown in the documentation:

public function personable(): MorphTo
{
    return $this->morphTo();
}

public function physicalPeople(): MorphTo
{
    return $this->personable()->whereHas('people', function (Builder $query) {
        $query->where('people.personable_type', 'physical');
    });
}

public function moralPeople(): MorphTo
{
    return $this->personable()->whereHas('people', function (Builder $query) {
        $query->where('people.personable_type', 'moral');
    });
}

2. Add the relations to the Resource class:

public function relations(RestRequest $request): array
{
    return [
        HasOne::make('referrer', ReferrerResource::class),
        HasMany::make('addresses', AddressResource::class),
        HasMany::make('documents', DocumentResource::class),
        HasMany::make('emails', EmailResource::class),
        HasMany::make('phones', PhoneResource::class),
        HasMany::make('clients', ClientResource::class),
        MorphTo::make('physicalPeople', PhysicalPeopleResource::class),
        MorphTo::make('moralPeople', MoralPeopleResource::class),
        HasOne::make('legalClassification', LegalClassificationResource::class),
        HasOne::make('promoter', PromoterResource::class),
        HasOne::make('referer', RefererResource::class),
        HasOne::make('rfc', DocumentResource::class),
        BelongsTo::make('type', TypeResource::class),
    ];
}

3.Make an API request that tries to resolve one of the MorphTo relations.

[mrsuarezg]

The above is using morph maps to enforce, but if I use the model class I get a 200 return code, but the relation is empty.

[GautierDele]

Hello, thanks for the feedback 😊

I'll add an unit test and come back to you in order to cover this
It won't take long

[GautierDele]

It seems i'm able to reproduce this, i'm on it

[GautierDele]

#146

I added a test to avoid problems in the future and updated documentation

https://laravel-rest-api.lomkit.com/resources/relationships#morph-to

Please update and try on your side, don't need to update the package 😉

[mrsuarezg]

First of all, thank you so much for your prompt response and for the partial solution! The updated documentation and example have definitely helped resolve part of the issue I was facing. I truly appreciate the effort. 🙌

However, after implementing your solution with my current code, I’ve encountered a scenario that still raises some questions:

// Updated code based on your suggestion
public function physicalPeople(): MorphTo
{
    return $this->morphTo('physicalPeople', 'personable_type', 'personable_id')
        ->whereHas('people', function (Builder $query) {
            $query->where('personable_type', 'physical');
        });
}

public function moralPeople(): MorphTo
{
    return $this->morphTo('moralPeople', 'personable_type', 'personable_id')
        ->whereHas('people', function (Builder $query) {
            $query->where('personable_type', 'moral');
        });
}

This works correctly for fetching data. However, when I attempt to apply filters or selections specific to the relationships (e.g., physicalPeople.surname for physicalPeople and moralPeople.name for moralPeople), I find that the current implementation doesn’t seem to handle these contextual differences between the relationships effectively.

For example:

physicalPeople should allow filtering or selecting attributes like surname, specific to physical relations.
moralPeople should handle attributes like name, specific to moral relations.
So far, I haven’t found an efficient way to address these differences in queries or selectors. Would you have any suggestions or recommendations for handling this case? Is this something that could be considered in future updates?

Thank you again for your time and willingness to assist. Any additional guidance would be greatly appreciated. 😊

[GautierDele]

I'm missing time by now unfortunately, did you find anything on this ?

[GautierDele]

I'm closing this, please reopen this if this is still going