[5.8] change BelongsTo::relation to BelongsTo::relationName(witho…

…ut breaking change) (#26724)

* Improved naming convention consistency.

* Renamed the constructor's parameter name too.

* add getRelation back as a deprecated method

src/Illuminate/Database/Eloquent/Relations/BelongsTo.php

@@ -35,7 +35,7 @@ class BelongsTo extends Relation
      *
      * @var string
      */
-    protected $relation;
+    protected $relationName;
 
     /**
      * The count of self joins.
@@ -51,13 +51,14 @@ class BelongsTo extends Relation
      * @param  \Illuminate\Database\Eloquent\Model  $child
      * @param  string  $foreignKey
      * @param  string  $ownerKey
-     * @param  string  $relation
+     * @param  string  $relationName
+     *
      * @return void
      */
-    public function __construct(Builder $query, Model $child, $foreignKey, $ownerKey, $relation)
+    public function __construct(Builder $query, Model $child, $foreignKey, $ownerKey, $relationName)
     {
         $this->ownerKey = $ownerKey;
-        $this->relation = $relation;
+        $this->relationName = $relationName;
         $this->foreignKey = $foreignKey;
 
         // In the underlying base relationship class, this variable is referred to as
@@ -219,9 +220,9 @@ public function associate($model)
         $this->child->setAttribute($this->foreignKey, $ownerKey);
 
         if ($model instanceof Model) {
-            $this->child->setRelation($this->relation, $model);
+            $this->child->setRelation($this->relationName, $model);
         } elseif ($this->child->isDirty($this->foreignKey)) {
-            $this->child->unsetRelation($this->relation);
+            $this->child->unsetRelation($this->relationName);
         }
 
         return $this->child;
@@ -236,7 +237,7 @@ public function dissociate()
     {
         $this->child->setAttribute($this->foreignKey, null);
 
-        return $this->child->setRelation($this->relation, null);
+        return $this->child->setRelation($this->relationName, null);
     }
 
     /**
@@ -366,8 +367,19 @@ public function getQualifiedOwnerKeyName()
      *
      * @return string
      */
+    public function getRelationName()
+    {
+        return $this->relationName;
+    }
+
+    /**
+     * Get the name of the relationship.
+     *
+     * @return string
+     * @deprecated The getRelationName() method should be used instead. Will be removed in Laravel 5.9.
+     */
     public function getRelation()
     {
-        return $this->relation;
+        return $this->relationName;
     }
 }

src/Illuminate/Database/Eloquent/Relations/MorphTo.php

@@ -181,7 +181,7 @@ protected function matchToMorphParents($type, Collection $results)
 
             if (isset($this->dictionary[$type][$ownerKey])) {
                 foreach ($this->dictionary[$type][$ownerKey] as $model) {
-                    $model->setRelation($this->relation, $result);
+                    $model->setRelation($this->relationName, $result);
                 }
             }
         }
@@ -203,7 +203,7 @@ public function associate($model)
             $this->morphType, $model instanceof Model ? $model->getMorphClass() : null
         );
 
-        return $this->parent->setRelation($this->relation, $model);
+        return $this->parent->setRelation($this->relationName, $model);
     }
 
     /**
@@ -217,7 +217,7 @@ public function dissociate()
 
         $this->parent->setAttribute($this->morphType, null);
 
-        return $this->parent->setRelation($this->relation, null);
+        return $this->parent->setRelation($this->relationName, null);
     }
 
     /**

tests/Database/DatabaseEloquentBelongsToTest.php

@@ -153,7 +153,7 @@ public function testAssociateMethodSetsForeignKeyOnModelById()
         $relation = $this->getRelation($parent);
         $parent->shouldReceive('setAttribute')->once()->with('foreign_key', 1);
         $parent->shouldReceive('isDirty')->once()->andReturn(true);
-        $parent->shouldReceive('unsetRelation')->once()->with($relation->getRelation());
+        $parent->shouldReceive('unsetRelation')->once()->with($relation->getRelationName());
         $relation->associate(1);
     }
 

tests/Database/DatabaseEloquentModelTest.php

@@ -1090,27 +1090,27 @@ public function testMorphToCreatesProperRelation()
         $relation = $model->morphToStub();
         $this->assertEquals('morph_to_stub_id', $relation->getForeignKeyName());
         $this->assertEquals('morph_to_stub_type', $relation->getMorphType());
-        $this->assertEquals('morphToStub', $relation->getRelation());
+        $this->assertEquals('morphToStub', $relation->getRelationName());
         $this->assertSame($model, $relation->getParent());
         $this->assertInstanceOf(EloquentModelSaveStub::class, $relation->getQuery()->getModel());
 
         // $this->morphTo(null, 'type', 'id');
         $relation2 = $model->morphToStubWithKeys();
         $this->assertEquals('id', $relation2->getForeignKeyName());
         $this->assertEquals('type', $relation2->getMorphType());
-        $this->assertEquals('morphToStubWithKeys', $relation2->getRelation());
+        $this->assertEquals('morphToStubWithKeys', $relation2->getRelationName());
 
         // $this->morphTo('someName');
         $relation3 = $model->morphToStubWithName();
         $this->assertEquals('some_name_id', $relation3->getForeignKeyName());
         $this->assertEquals('some_name_type', $relation3->getMorphType());
-        $this->assertEquals('someName', $relation3->getRelation());
+        $this->assertEquals('someName', $relation3->getRelationName());
 
         // $this->morphTo('someName', 'type', 'id');
         $relation4 = $model->morphToStubWithNameAndKeys();
         $this->assertEquals('id', $relation4->getForeignKeyName());
         $this->assertEquals('type', $relation4->getMorphType());
-        $this->assertEquals('someName', $relation4->getRelation());
+        $this->assertEquals('someName', $relation4->getRelationName());
     }
 
     public function testBelongsToManyCreatesProperRelation()