hasManyDeepFromRelation with table aliases

[ockle]

This was already brought up in #22, but that ticket went in a different direction. Can table aliases be used with hasManyDeepFromRelations?

[staudenmeir]

What do your individual relationships look like?

[ockle]

This is essentially what I'm doing:

class User extends Model
{
    public function lowerLevels()
    {
        return $this->belongsToMany(LowerLevel::class);
    }

    public function allLowerLevelsBelongingToAllLowerLevelsUpperLevels()
    {
        return $this->hasManyDeepFromRelations($this->lowerLevels(), (new LowerLevel)->upperLevel(), (new UpperLevel)->lowerLevels());
    }
}

class LowerLevel extends Model
{
    public function upperLevel()
    {
        return $this->belongsTo(UpperLevel::class);
    }
}

class UpperLevel extends Model
{
    public function lowerLevels()
    {
        return $this->hasMany(LowerLevel::class);
    }
}

[staudenmeir]

You need to define a "real" HasManyDeep relationship:

class User extends Model
{
    public function allLowerLevelsBelongingToAllLowerLevelsUpperLevels()
    {
        return $this->hasManyDeep(
            LowerLevel::class,
            ['lower_level_user', LowerLevel::class.' as alias', UpperLevel::class],
            [null, null, 'id'],
            [null, null, 'upper_level_id']
        );
    }
}

class LowerLevel extends Model
{
    use \Staudenmeir\EloquentHasManyDeep\HasTableAlias;
}

[ockle]

That does indeed work, thanks :)

However I find it much harder to work out how to construct the relationship that way. I feel like the hasManyDeepFromRelations method that you can pass a chain of existing relationships in, in the exact chain order, and it "magically" works, is the stand out feature of this fantastic package. If every example can be implemented via hasManyDeepFromRelations, then I would think that should be shown as the primary way of using the package, with hasManyDeep as the fallback for any edge cases that can't, such as this.

Having said that, is there any way something like the following could be made to work:

$lowerLevel = new LowerLevel;
$lowerLevel->setTable($lowerLevel->getTable() . ' as table_alias');
$this->hasManyDeepFromRelations($this->lowerLevels(), $lowerLevel->upperLevel(), (new UpperLevel)->lowerLevels());

or as as an additional method in the HasTableAlias trait:

$this->hasManyDeepFromRelations($this->lowerLevels(), (new LowerLevel)->alias('table_alias')->upperLevel(), (new UpperLevel)->lowerLevels());

and hasManyDeepFromRelations then pick up the table name to use from there?

[staudenmeir]

Yeah, that's not ideal. I've looked into alternatives like automatic aliasing of duplicate tables, but haven't found a good solution yet. I'll try again and see if I can make your suggestions work.

[staudenmeir]

I've released a new version that adds the setAlias() method (requires Laravel 6):

return $this->hasManyDeepFromRelations(
    $this->lowerLevels(),
    (new LowerLevel)->setAlias('table_alias')->upperLevel(),
    (new UpperLevel)->lowerLevels()
);