[9.x] Extract child route model relationship name into a method (#43597)

* Extract child route model relationship name

* Fix style

* Update Model.php

Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Illuminate/Database/Eloquent/Model.php

@@ -1980,7 +1980,7 @@ public function resolveSoftDeletableChildRouteBinding($childType, $value, $field
      */
     protected function resolveChildRouteBindingQuery($childType, $value, $field)
     {
-        $relationship = $this->{Str::plural(Str::camel($childType))}();
+        $relationship = $this->{$this->childRouteBindingRelationshipName($childType)}();
 
         $field = $field ?: $relationship->getRelated()->getRouteKeyName();
 
@@ -1994,6 +1994,17 @@ protected function resolveChildRouteBindingQuery($childType, $value, $field)
                 : $relationship->getRelated()->resolveRouteBindingQuery($relationship, $value, $field);
     }
 
+    /**
+     * Retrieve the child route model binding relationship name for the given child type.
+     *
+     * @param  string  $childType
+     * @return string
+     */
+    protected function childRouteBindingRelationshipName($childType)
+    {
+        return Str::plural(Str::camel($childType));
+    }
+
     /**
      * Retrieve the model for a bound value.
      *