/** * Returns the list of fields that should be returned by default by {@see \rock\components\ArrayableTrait::toArray()} when no specific fields are specified. * * A field is a named element in the returned array by {@see \rock\components\ArrayableTrait::toArray()}. * * This method should return an array of field names or field definitions. * If the former, the field name will be treated as an object property name whose value will be used * as the field value. If the latter, the array key should be the field name while the array value should be * the corresponding field definition which can be either an object property name or a PHP callable * returning the corresponding field value. The signature of the callable should be: * * ```php * function ($field, $model) { * // return field value * } * ``` * * For example, the following code declares four fields: * * - `email`: the field name is the same as the property name `email`; * - `firstName` and `lastName`: the field names are `firstName` and `lastName`, and their * values are obtained from the `first_name` and `last_name` properties; * - `fullName`: the field name is `fullName`. Its value is obtained by concatenating `first_name` * and `last_name`. * * ```php * return [ * 'email', * 'firstName' => 'first_name', * 'lastName' => 'last_name', * 'fullName' => function () { * return $this->first_name . ' ' . $this->last_name; * }, * ]; * ``` * * In this method, you may also want to return different lists of fields based on some context * information. For example, depending on the privilege of the current application user, * you may return different sets of visible fields or filter out some fields. * * The default implementation of this method returns the public object member variables. * * @return array the list of field names or field definitions. * @see toArray() */ public function fields() { $fields = array_keys(ObjectHelper::getObjectVars($this)); return array_combine($fields, $fields); }