Laravel can't access pivot additional column from pivot model itself

[shabaz-ejaz]

• Laravel Version: 5.5.35
• PHP Version: 7.0.10
• Database Driver & Version: MySQL 5.7.14

Description:

I have a pivot model called UserTask in which I have an accessor function:

class UserTask extends Pivot implements HasMedia
{
    use HasMediaTrait;

    public function getCompletedAttribute()
    {
        return $this->getMedia()->isEmpty() && $this->completed;
    }



    public function task()
    {
        return $this->belongsTo(Task::class);
    }

}

I specify the relation in my Task model like this:

class Task extends Model
{
    public function users()
    {
        return $this->belongsToMany(User::class, 'user_task')->using('App\Models\UserTask')->withPivot('completed');
    }
}

I get the following error:

"message": "Undefined property: App\Models\UserTask::$completed",

Anyone know why this is happening?

[kevinruscoe]

Don't you need to use ->withPivot('completed'); to ask Eloquent to get this attribute?

[staudenmeir]

Do you still have that problem?

[CyberiaResurrection]

@staudenmeir , I've also tripped over this problem - to both cast the pivot values as a model and to also be able to access pivot model columns directly (without having to do an additional $PIVOT_MODEL::find($pivot_id) ), I have to use both ->using(... and withPivot(.... , like so:

return $this->belongsToMany(ForeignModel::class, 'pivot_table')->using(PivotModel::class)->withPivot(['firstCol', 'secondCol', .... ])

[staudenmeir]

@CyberiaResurrection Can you please provide more details? What exactly is the issue?

[CyberiaResurrection]

If I define the pivot table with additional columns but don't cast the pivot values to a model, then I get a bunch of values in $foo->manyToManyRelation()->first()->pivot and not a model. This is problematic when said pivot models also have their own, independent relations to other models (not just the implied belongsTo relations to the parent models on each side of the original M:N relation).

If I go the other way, and cast the pivot values to a model but don't specify the extra columns, that usually breaks the extra relations where they are defined on the pivot models, as the requisite key value is usually missing.

As (Morph)Pivot extends the Model class, I don't see a reason why, if my application setup needs it, to refrain from adding those extra relations directly onto pivot models.

I got the impression from the documentation that ->using(PivotModel::class) actually implied ->withPivot(['firstColumn','secondColumn', ...]), and wasted a good few hours chasing that mistaken assumption up the garden path.

[staudenmeir]

->using(PivotModel::class) can't imply ->withPivot(['firstColumn','secondColumn', ...]) because Eloquent doesn't know what columns the pivot table contains.

[CyberiaResurrection]

That will slow things down somewhat, yes. I guess joining all pivot table columns (when using a pivot model) will be too much brute-force-over-ignorance?

[staudenmeir]

That's not possible: We can't just select pivot_table.* because we have to alias the pivot columns. In order to do this, we have to know their names.

The only way would be a separate query that retrieves the list of columns from a meta table like information_schema.columns.

[CyberiaResurrection]

And that would defeat the point. I'm not sure if anything can be done except updating the docs to note that my assumption doesn't hold.

[driesvints]

I'm not sure this can be fixed. But indeed, perhaps a note to the docs to clarify that you can't use using in combination with withPivot might be in order. I'll try to send something in for this later or feel free to do so yourself.

[CyberiaResurrection]

@driesvints , I'm not sure how to reference another repo's pull requests, so have gone for simplest way I could think of:
laravel/docs#4744

[driesvints]

Closing as this has been added to the docs.