Yii2 使用核心验证器：比对日期值，新增验证规则(条件式验证：当一个日期值不为空时，另一个日期值必填)

1、实现一个获取文章列表的接口，需要基于日期控件查询数据，如图1

图1

2、验证规则配置如下

	['from_created_at', 'datetime', 'format' => 'php:Y-m-d H:i:s', 'timestampAttribute' => 'from_created_at', 'on' => 'index'], //index
	['to_created_at', 'datetime', 'format' => 'php:Y-m-d H:i:s', 'timestampAttribute' => 'to_created_at', 'on' => 'index'], //index
	['from_created_at', 'compare', 'compareAttribute' => 'to_created_at', 'operator' => '<', 'enableClientValidation' => false], //index

3、from_created_at、to_created_at皆为空，验证通过，如图2

图2

4、日期(datetime，例：2017-03-03 12:05:54)：from_created_at、to_created_at；验证不通过，如图3

图3

{
    "code": 20004,
    "message": "数据验证失败：属性 From Created At 的格式无效。"
}

5、比对日期值(from_created_at < to_created_at)：from_created_at, to_created_at；验证不通过，如图4

图4

{
    "code": 20004,
    "message": "数据验证失败：From Created At的值必须小于\"To Created At\"。"
}

6、如果from_created_at不为空，to_created_at为空，验证不通过，如图5

图5

{
    "code": 20004,
    "message": "数据验证失败：From Created At的值必须小于\"To Created At\"。"
}

7、如果from_created_at为空，to_created_at不为空，验证通过，不符合预期，预期：或者皆为空，或者皆不为空

8、验证规则配置如下，只有在一个日期值不为空时，才验证另一个日期值为必填

	['from_created_at', 'datetime', 'format' => 'php:Y-m-d H:i:s', 'timestampAttribute' => 'from_created_at', 'on' => 'index'], //index
	['to_created_at', 'datetime', 'format' => 'php:Y-m-d H:i:s', 'timestampAttribute' => 'to_created_at', 'on' => 'index'], //index
	['from_created_at', 'required', 'when' => function($model) {
		return !empty($model->to_created_at);
	}], //index
	['to_created_at', 'required', 'when' => function($model) {
		return !empty($model->from_created_at);
	}], //index
	['from_created_at', 'compare', 'compareAttribute' => 'to_created_at', 'operator' => '<', 'enableClientValidation' => false], //index