[5.8] Add whereHasMorph()

[staudenmeir]

Due to the nature of polymorphism, whereHas() doesn't work with MorphTo relationships (#5429, #18523).

As a solution, @timacdonald and I are proposing whereHasMorph() and the corresponding methods:

Comment::whereHasMorph('commentable', [Post::class, Video::class], function ($query) {
    $query->where('title', 'foo');
})->get();

select * from "comments"
where (
  (
    "commentable_type" = 'App\Post' and exists (
      select * from "posts" where "comments"."commentable_id" = "posts"."id" and "title" = 'foo'
    )
  ) or (
    "commentable_type" = 'App\Video' and exists (
      select * from "videos" where "comments"."commentable_id" = "videos"."id" and "title" = 'foo'
    )
  )
)

By creating a temporary BelongsTo relationship for each type and allowing relationship instances as the first argument of has(), we can reuse most of the existing code.

If the user has registered custom aliases in the morphMap, they need to provide them instead of class names:

To simplify queries with different constraints, we pass the type as the second parameter:

Comment::whereHasMorph('commentable', [Post::class, Video::class], function ($query, $type) {
    if ($type === Post::class) {
        // $query->
    }

    if ($type === Video::class) {
        // $query->
    }
});

You can also provide a wildcard and let Laravel get the possible types from the database:

Comment::whereHasMorph('commentable', '*', function ($query) {
    $query->where('title', 'foo');
})->get();

The downside here is the additional query that should be mentioned in the docs.

Theoretically, you could use * as an alias, but we think it's a better choice than something like null .

[phroggyy]

Is there a reason we can't do a morphMap lookup to allow always passing classes? Seems a bit flawed to have to change things in multiple places, unless I'm missing something. Should just be a matter of Relation::getMorphedModel($fqcn)

[timacdonald]

I might be miss understanding what you mean, but as it stands you can pass:

• Only class types i.e. fqcn
• Only morph map values
• A mixture of morph and class types

i.e. all of the following work...

Relation::morphMap(['posts' => Post::class, 'videos' => Video::class]);

// only classes
Comment::whereHasMorph('commentable', [Post::class, Video::class], function ($query) {
    //
})->etc(...);

// only morph values
Comment::whereHasMorph('commentable', ['posts', 'videos'], function ($query) {
    //
})->etc(...);

// a mixture of both
Comment::whereHasMorph('commentable', ['posts', Video::class], function ($query) {
    //
})->etc(...);

We have to create an on-the-fly relationship - hence passing the $belongsTo relation instance to the has method.

Here is where the morph map lookup is happening:

framework/src/Illuminate/Database/Eloquent/Concerns/QueriesRelationships.php

Lines 233 to 246 in 8fe3f1f

	protected function getBelongsToRelation(MorphTo $relation, $type)
	{
	$belongsTo = Relation::noConstraints(function () use ($relation, $type) {
	return $this->model->belongsTo(
	Relation::getMorphedModel($type) ?? $type,
	$relation->getForeignKeyName(),
	$relation->getOwnerKeyName()
	);
	});
	$belongsTo->getQuery()->mergeConstraintsFrom($relation->getQuery());
	return $belongsTo;
	}

@phroggyy let us know if that addresses your concern or if I'm way off base with what you mean 🙂

---

Another nice thing about this is that you have access to the scopes on the models as well. So if Video and Post all share a wherePublished() scope you can access it...

Comment::whereHasMorph('commentable', [Post::class, Video::class], function ($query) {
    $query->wherePublished();
})->etc(...);

[phroggyy]

Ah, gotcha. In that case, the phrasing of the PR is wrong:

If the user has registered custom aliases in the morphMap, they need to provide them instead of class names:

As per your explanation, this is not true. The user may pass a class name or morph value, but whether the morph map is used doesn't matter.

[timacdonald]

🤦‍♂️ Sorry, I actually misspoke. What @staudenmeir said is how this implementation currently works.

[timacdonald]

I've just created a PR to @staudenmeir’s branch that does the reverse lookup and allows classes even when a morph value has been specified - which matches what I said in my earlier comment.

But we might just need to consider if there are any implications to this before merging. Thoughts?

[staudenmeir]

I don't think it's a good idea to allow both class names and aliases.

What if users only provide class names and Laravel handles the aliases? This way, users wouldn't have to adjust the queries when they add a morphMap.

[timacdonald]

I don't personally use a morph map, so not sure how valuable my opinion in on this specific part, but that sounds like a good way to go about it.

Either way, I've just created a PR for this behaviour as well.

[staudenmeir]

whereHasMorph() now only allows class names and handles aliases itself:

Relation::morphMap(['posts' => Post::class]);

Comment::whereHasMorph('commentable', [Post::class, Video::class], function ($query) {
    $query->where('title', 'foo');
})->get();

[taylorotwell]

Nice one!

[denitsa-md]

I just opened this issue #29138 related to this PR. Not sure if I'm doing something wrong but can't seem to get the doesntHaveMorph to work :)

[mikkopursuittechnology]

With this improvement can you do nested relationship on morphed classes?

Comment::whereHasMorph('commentable', [Post::class, Video::class], function ($query) {
    $query->has('author');
})->get();

In the example above. I'm trying to look for Comments from Posts and Videos that has an author.

[pelmered]

This is a great addition, but I can't get it to work with a morphToMany-relation. It does not query *_id and *_type in the intermediate table.
I guess we need a whereHasMorphMany as well?

[staudenmeir]

@mikkopursuittechnology Yes, you can.

@pelmered whereHasMorph() is only for MorphTo relationships. Use whereHas() for all other relationships.

[pelmered]

@staudenmeir Ok, but whereHas() doesn't work with MorphToMany(). When I use whereHas() I get a RuntimeException with message: Please use whereHasMorph() for MorphTo relationships.

And with whereHasMorph() it queries the wrong table.

Conclusion: we need a whereHasMorphMany() as well for morphToMany-relations.

[staudenmeir]

@pelmered How is your relationship defined? This exception is only thrown for MorphTo relationships.

[pelmered]

@staudenmeir Yes, you where right. Where was an error in the inverse of the relationship. Sorry about that. whereHas() works fine.

[usamamuneerchaudhary]

and how to implement the inverse of the relationship?

[hazemwehbi]

Hello all,
Can I find in anyone of you any piece of code which apply or use whereHasMorph() ?
Thx in advance

[staudenmeir]

@hazemwehbi https://laravel.com/docs/eloquent-relationships#querying-polymorphic-relationships

[hazemwehbi]

Thx a lot, I already saw the laravel documentation and followed it but I don't know why it's not working to me.
It show me this error.
"Maximum function nesting level of '250' reached, aborting!"