如果您不在乎当用户提供两个字段中的任何一个时两个字段都显示错误：
此解决方案比其他答案更短，并且不需要新的验证器类型/类：

$rules = [
  ['email', 'required', 'when' => function($model) { return empty($model->phone); }],
  ['phone', 'required', 'when' => function($model) { return empty($model->email); }],
];

如果您希望有一个自定义的错误消息，只需设置message选项：

$rules = [
  [
    'email', 'required',
    'message' => 'Either email or phone is required.',
    'when' => function($model) { return empty($model->phone); }
  ],
  [
    'phone', 'required',
    'message' => 'Either email or phone is required.',
    'when' => function($model) { return empty($model->email); }
  ],
];

规则应该是：

['email', 'either', 'params' => ['other' => 'phone']],

和法：

public function either($attribute_name, $params)
{
    $field1 = $this->getAttributeLabel($attribute_name);
    $field2 = $this->getAttributeLabel($params['other']);
    if (empty($this->$attribute_name) && empty($this->{$params['other']})) {
        $this->addError($attribute_name, Yii::t('user', "either {$field1} or {$field2} is required."));
    }
}

改进的变体

['gipsy_team_name', 'either', 'skipOnEmpty'=>false, 'params' => ['other' => 'poker_strategy_nick_name']],
        ['vkontakte', 'either', 'skipOnEmpty'=>false, 'params' => ['other' => ['odnoklasniki','odnoklasniki']]],

添加了**'skipOnEmpty'=〉false**用于强制验证，并且'other'可以是数组

/**
 * validation rule
 * @param string $attribute_name
 * @param array $params
 */
public function either($attribute_name, $params)
{
    /**
     * validate actula attribute
     */
    if(!empty($this->$attribute_name)){
        return;
    }

    if(!is_array($params['other'])){
        $params['other'] = [$params['other']];
    }

    /**
     * validate other attributes
     */
    foreach($params['other'] as $field){
        if(!empty($this->$field)){
            return;
        }
    }

    /**
     * get attributes labels
     */
    $fieldsLabels = [$this->getAttributeLabel($attribute_name)];
    foreach($params['other'] as $field){
        $fieldsLabels[] = $this->getAttributeLabel($field);
    }

    $this->addError($attribute_name, \Yii::t('poker_reg', 'One of fields "{fieldList}" is required.',[
        'fieldList' => implode('"", "', $fieldsLabels),
    ]));

}