MorphTo Relation ignores parent $timestamp when touching

[tiwac100]

• Laravel Version: 5.8.18
• PHP Version: 7.3.2
• Database Driver & Version: MySQL 5.7

Description:

When creating / updating / deleting a child belonging to a parent through a MorphTo relation Eloquent tries to updated the parents updated_at column regardless of the parents $timestamps property when the parent is listed in $touches.

Because this is a polymorphic relation and not all parents may have timestamps I would expect that parents with $timestamps = false are ignored when touching.

(I guess this may not only be relevant for MorphTo relations but others as well)

Steps To Reproduce:

Parent.php

class Parent extends Model
{
    public $timestamps = false;

    public function children(): MorphMany
    {
        return $this->morphMany(Child::class, 'children');
    }

}

Child.php

class Child extends Model
{
    protected $touches = ['parent'];

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

}

$parent->children()->save(new Child()); throws Illuminate\Database\QueryException: SQLSTATE[HY000]: General error: 1 no such column: updated_at (SQL: update "parents" set "updated_at" = 2019-05-28 11:02:21 where "parents"."id" = 1)

[driesvints]

That indeed seems like a bug to me. Welcoming prs for this.

[driesvints]

Pr for this was merged.