[7.x] Add 'loadMorph' and 'loadMorphCount' on Eloquent Model (#32760)

* Add 'loadMorph' method to Eloquent Model

* Add 'loadMorphCount' method to Eloquent model

* Fix StyleCI issue

Co-authored-by: GuntherDebrauwer <22586858+GuntherDebrauwer@users.noreply.github.com>

src/Illuminate/Database/Eloquent/Model.php

@@ -520,6 +520,22 @@ public function load($relations)
         return $this;
     }
 
+    /**
+     * Eager load relationships on the polymorphic relation of a model.
+     *
+     * @param  string $relation
+     * @param  array  $relations
+     * @return $this
+     */
+    public function loadMorph($relation, $relations)
+    {
+        $className = get_class($this->{$relation});
+
+        $this->{$relation}->load($relations[$className] ?? []);
+
+        return $this;
+    }
+
     /**
      * Eager load relations on the model if they are not already eager loaded.
      *
@@ -550,6 +566,22 @@ public function loadCount($relations)
         return $this;
     }
 
+    /**
+     * Eager load relationship counts on the polymorphic relation of a model.
+     *
+     * @param  string $relation
+     * @param  array  $relations
+     * @return $this
+     */
+    public function loadMorphCount($relation, $relations)
+    {
+        $className = get_class($this->{$relation});
+
+        $this->{$relation}->loadCount($relations[$className] ?? []);
+
+        return $this;
+    }
+
     /**
      * Increment a column's value by a given amount.
      *

tests/Integration/Database/EloquentMorphCountLazyEagerLoadingTest.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace Illuminate\Tests\Integration\Database\EloquentMorphCountLazyEagerLoadingTest;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Tests\Integration\Database\DatabaseTestCase;
+
+/**
+ * @group integration
+ */
+class EloquentMorphCountLazyEagerLoadingTest extends DatabaseTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        Schema::create('likes', function (Blueprint $table) {
+            $table->increments('id');
+            $table->unsignedInteger('post_id');
+        });
+
+        Schema::create('posts', function (Blueprint $table) {
+            $table->increments('id');
+        });
+
+        Schema::create('comments', function (Blueprint $table) {
+            $table->increments('id');
+            $table->string('commentable_type');
+            $table->integer('commentable_id');
+        });
+
+        $post = Post::create();
+
+        tap((new Like)->post()->associate($post))->save();
+        tap((new Like)->post()->associate($post))->save();
+
+        (new Comment)->commentable()->associate($post)->save();
+    }
+
+    public function testLazyEagerLoading()
+    {
+        $comment = Comment::first();
+
+        $comment->loadMorphCount('commentable', [
+            Post::class => ['likes'],
+        ]);
+
+        $this->assertTrue($comment->relationLoaded('commentable'));
+        $this->assertEquals(2, $comment->commentable->likes_count);
+    }
+}
+
+class Comment extends Model
+{
+    public $timestamps = false;
+
+    public function commentable()
+    {
+        return $this->morphTo();
+    }
+}
+
+class Post extends Model
+{
+    public $timestamps = false;
+
+    public function likes()
+    {
+        return $this->hasMany(Like::class);
+    }
+}
+
+class Like extends Model
+{
+    public $timestamps = false;
+
+    public function post()
+    {
+        return $this->belongsTo(Post::class);
+    }
+}

tests/Integration/Database/EloquentMorphLazyEagerLoadingTest.php

@@ -0,0 +1,78 @@
+<?php
+
+namespace Illuminate\Tests\Integration\Database\EloquentMorphLazyEagerLoadingTest;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Tests\Integration\Database\DatabaseTestCase;
+
+/**
+ * @group integration
+ */
+class EloquentMorphLazyEagerLoadingTest extends DatabaseTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        Schema::create('users', function (Blueprint $table) {
+            $table->increments('id');
+        });
+
+        Schema::create('posts', function (Blueprint $table) {
+            $table->increments('post_id');
+            $table->unsignedInteger('user_id');
+        });
+
+        Schema::create('comments', function (Blueprint $table) {
+            $table->increments('id');
+            $table->string('commentable_type');
+            $table->integer('commentable_id');
+        });
+
+        $user = User::create();
+
+        $post = tap((new Post)->user()->associate($user))->save();
+
+        (new Comment)->commentable()->associate($post)->save();
+    }
+
+    public function testLazyEagerLoading()
+    {
+        $comment = Comment::first();
+
+        $comment->loadMorph('commentable', [
+            Post::class => ['user'],
+        ]);
+
+        $this->assertTrue($comment->relationLoaded('commentable'));
+        $this->assertTrue($comment->commentable->relationLoaded('user'));
+    }
+}
+
+class Comment extends Model
+{
+    public $timestamps = false;
+
+    public function commentable()
+    {
+        return $this->morphTo();
+    }
+}
+
+class Post extends Model
+{
+    public $timestamps = false;
+    protected $primaryKey = 'post_id';
+
+    public function user()
+    {
+        return $this->belongsTo(User::class);
+    }
+}
+
+class User extends Model
+{
+    public $timestamps = false;
+}