[5.5] Completed BelongsToMany Parent Key Change (#21044)

* Resolve Eager Loading Problem with BelongsToMany

This resolves the problem of the relation not making use of the parentKey for the parent Models.

* Completed BelongsToMany Parent Key Change

This resolves the issue where BelongsToMany.php makes use of parentKey, but this concern (InteractsWithPivotTable) does not make use of parentKey at all, and instead still uses the old $this->parent->getKey() rather than $this->parent->{$this->parentKey}

This references this change e4f8884 which has been superceded by 00c2c5a

There also requires a change in BelongsToMany to resolve Eager Loading.

Author: Upperfoot

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

@@ -194,7 +194,7 @@ protected function addWhereConstraints()
      */
     public function addEagerConstraints(array $models)
     {
-        $this->query->whereIn($this->getQualifiedForeignPivotKeyName(), $this->getKeys($models));
+        $this->query->whereIn($this->getQualifiedForeignPivotKeyName(), $this->getKeys($models, $this->parentKey));
     }
 
     /**
@@ -229,7 +229,7 @@ public function match(array $models, Collection $results, $relation)
         // children back to their parent using the dictionary and the keys on the
         // the parent models. Then we will return the hydrated models back out.
         foreach ($models as $model) {
-            if (isset($dictionary[$key = $model->getKey()])) {
+            if (isset($dictionary[$key = $model->{$this->parentKey}])) {
                 $model->setRelation(
                     $relation, $this->related->newCollection($dictionary[$key])
                 );

src/Illuminate/Database/Eloquent/Relations/Concerns/InteractsWithPivotTable.php

@@ -293,7 +293,7 @@ protected function baseAttachRecord($id, $timed)
     {
         $record[$this->relatedPivotKey] = $id;
 
-        $record[$this->foreignPivotKey] = $this->parent->getKey();
+        $record[$this->foreignPivotKey] = $this->parent->{$this->parentKey};
 
         // If the record needs to have creation and update timestamps, we will make
         // them by calling the parent model's "freshTimestamp" method which will
@@ -439,7 +439,7 @@ protected function newPivotQuery()
             call_user_func_array([$query, 'whereIn'], $arguments);
         }
 
-        return $query->where($this->foreignPivotKey, $this->parent->getKey());
+        return $query->where($this->foreignPivotKey, $this->parent->{$this->parentKey});
     }
 
     /**