code: function permittedAttributes() {
          let filteredKeys = ghostBookshelf.Model.prototype.permittedAttributes.apply(this, arguments);
  
          this.relationships.forEach((key) => {
              filteredKeys.push(key);
          });
  
          return filteredKeys;
      }
docs: The base model keeps only the columns, which are defined in the schema.
  We have to add the relations on top, otherwise bookshelf-relations
  has no access to the nested relations, which should be updated.