Merge pull request #81 from psalm/polymorphic-support

feature: support for polymorphic relations

src/PropertyProvider/ModelPropertyProvider.php

@@ -2,11 +2,17 @@
 
 namespace Psalm\LaravelPlugin\PropertyProvider;
 
+use Illuminate\Database\Eloquent\Collection;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Database\Eloquent\Relations\HasManyThrough;
+use Illuminate\Database\Eloquent\Relations\MorphMany;
 use PhpParser;
 use Psalm\Context;
 use Psalm\CodeLocation;
 use Psalm\Type;
 use Psalm\StatementsSource;
+use function in_array;
 use function str_replace;
 
 class ModelPropertyProvider implements
@@ -110,12 +116,20 @@ class ModelPropertyProvider implements
             if (!$methodReturnType) {
                 return Type::getMixed();
             }
+
+            /** @var \Psalm\Type\Union|null $modelType */
+            $modelType = null;
+            /** @var \Psalm\Type\Atomic\TGenericObject|null $relationType */
+            $relationType = null;
+
             // In order to get the property value, we need to decipher the generic relation object
             foreach ($methodReturnType->getAtomicTypes() as $atomicType) {
                 if (!$atomicType instanceof Type\Atomic\TGenericObject) {
                     continue;
                 }
 
+                $relationType = $atomicType;
+
                 foreach ($atomicType->getChildNodes() as $childNode) {
                     if (!$childNode instanceof Type\Union) {
                         continue;
@@ -124,12 +138,25 @@ class ModelPropertyProvider implements
                         if (!$atomicType instanceof Type\Atomic\TNamedObject) {
                             continue;
                         }
-                        return $childNode;
+
+                        $modelType = $childNode;
+                        break 3;
                     }
                 }
             }
 
-            return Type::getMixed();
+            $returnType = $modelType;
+
+            // these methods return collection instances
+            if ($modelType && $relationType && in_array($relationType->value, [BelongsToMany::class, HasMany::class, HasManyThrough::class, MorphMany::class])) {
+                $returnType = new Type\Union([
+                    new Type\Atomic\TGenericObject(Collection::class, [
+                        $modelType
+                    ]),
+                ]);
+            }
+
+            return $returnType ?: Type::getMixed();
         }
 
         if (self::accessorExists($codebase, $fq_classlike_name, $property_name)) {

src/Stubs/MorphMany.stubphp

@@ -0,0 +1,16 @@
+<?php
+
+namespace Illuminate\Database\Eloquent\Relations;
+
+use Illuminate\Database\Eloquent\Collection;
+use Illuminate\Database\Eloquent\Model;
+
+/**
+* @template TRelatedModel of Model
+* @template-extends MorphOneOrMany<TRelatedModel>
+* @mixin \Illuminate\Database\Eloquent\Builder<TRelatedModel>
+*/
+class MorphMany extends MorphOneOrMany
+{
+
+}

src/Stubs/MorphOneOrMany.stubphp

@@ -0,0 +1,16 @@
+<?php
+
+namespace Illuminate\Database\Eloquent\Relations;
+
+use Illuminate\Database\Eloquent\Collection;
+use Illuminate\Database\Eloquent\Model;
+
+/**
+* @template TRelatedModel of Model
+* @template-extends HasOneOrMany<TRelatedModel>
+* @mixin \Illuminate\Database\Eloquent\Builder<TRelatedModel>
+*/
+class MorphOneOrMany extends HasOneOrMany
+{
+
+}

tests/Models/Comment.php

@@ -4,6 +4,7 @@ namespace Tests\Psalm\LaravelPlugin\Models;
 
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\MorphTo;
 
 final class Comment extends Model
 {
@@ -14,4 +15,12 @@ final class Comment extends Model
     {
         return $this->belongsTo(Post::class);
     }
+
+    /**
+     * Get the owning commentable model.
+     */
+    public function commentable(): MorphTo
+    {
+        return $this->morphTo();
+    }
 }

tests/Models/Video.php

@@ -0,0 +1,18 @@
+<?php declare(strict_types=1);
+
+namespace Tests\Psalm\LaravelPlugin\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\MorphMany;
+
+final class Video extends Model
+{
+    /**
+    * Get all of the video's comments.
+    * @psalm-return MorphMany<Comment>
+    */
+    public function comments(): MorphMany
+    {
+        return $this->morphMany(Comment::class, 'commentable');
+    }
+}

tests/acceptance/EloquentRelationTypes.feature

@@ -22,12 +22,14 @@ Feature: Eloquent Relation Types
 
       use \Illuminate\Database\Eloquent\Builder;
       use \Illuminate\Database\Eloquent\Model;
+      use \Illuminate\Database\Eloquent\Collection;
       use \Illuminate\Database\Eloquent\Relations\HasOne;
       use \Illuminate\Database\Eloquent\Relations\BelongsTo;
       use \Illuminate\Database\Eloquent\Relations\BelongsToMany;
       use \Illuminate\Database\Eloquent\Relations\HasMany;
       use \Illuminate\Database\Eloquent\Relations\HasManyThrough;
       use \Illuminate\Database\Eloquent\Relations\HasOneThrough;
+      use \Illuminate\Database\Eloquent\Relations\MorphMany;
       use \Illuminate\Database\Eloquent\Relations\MorphTo;
 
       use Tests\Psalm\LaravelPlugin\Models\Comment;
@@ -37,6 +39,7 @@ Feature: Eloquent Relation Types
       use Tests\Psalm\LaravelPlugin\Models\Post;
       use Tests\Psalm\LaravelPlugin\Models\Role;
       use Tests\Psalm\LaravelPlugin\Models\User;
+      use Tests\Psalm\LaravelPlugin\Models\Video;
       """
 
   Scenario: Models can declare one to one relationships
@@ -160,6 +163,46 @@ Feature: Eloquent Relation Types
     When I run Psalm
     Then I see no errors
 
+  Scenario: Models can declare many to many polymorphic relationships
+    Given I have the following code
+    """
+    final class Repository
+    {
+      /**
+      * @psalm-return MorphMany<Comment>
+      */
+      public function getCommentsRelation(Video $video): MorphMany {
+        return $video->comments();
+      }
+
+      /**
+      * @psalm-return Collection<Comment>
+      */
+      public function getComments(Video $video): Collection {
+        return $video->comments;
+      }
+    }
+    """
+    When I run Psalm
+    Then I see no errors
+
+  Scenario: Polymorphic models can retrieve their inverse relation
+    Given I have the following code
+    """
+    final class Repository
+    {
+      /**
+      * todo: this should be a union of possible types...
+      * @psalm-return mixed
+      */
+      public function getCommentable(Comment $comment) {
+        return $comment->commentable;
+      }
+    }
+    """
+    When I run Psalm
+    Then I see no errors
+
   Scenario: Relationships can be accessed via a property
     Given I have the following code
     """