readme update

readme.md

@@ -1,3 +1,9 @@
+
+**DISCLAIMER : ELOQUENT FUNCTIONS OF THIS PACKAGE WILL BREAK EAGERLOADING OF BELONGSTOMANY RELATIONSHIPS**
+
+*This package is not compatible with belongsToMany relationships due to the indexation of entries. It is recommended not to use this package until I submit a solution to index collections properly*
+
+
 ## Utility classes for Laravel >= 5.8 
 ### Highest Laravel compatibily tested as of this readme : 7.9.2
 
@@ -37,6 +43,11 @@ Base Model class offers:
 
 <br>Collection as results of queries on a Model return an instance of `khwadj\Eloquent\Collection` that is indexed by primary key
 
+**CAREFUL : THIS WILL BREAK EAGERLOADING OF BELONGSTOMANY RELATIONSHIPS**
+
+*This package is not compatible with belongsToMany relationships due to the indexation of entries. It is recommended not to use this package until I submit a solution to index collections properly*
+
+
 ```
 $models = MyModel::all();
 // get the model with primary key = 1

src/Eloquent/Collection.php

@@ -29,7 +29,7 @@ public function add($item, $key = NULL)
             if ( $item instanceof Model ) $key = $item->getKey();
         }
 
-        if ( $key ) $this->items[$key] = $item;
+        if ( $key !== NULL ) $this->items[$key] = $item;
         else $this->items[] = $item;
 
         return $this;