Question

我想要实现的是让用户检查一些复选框，之后我会对选中的项目执行一些操作。我在以下控制器代码中收到以下错误：

这是错误，它抱怨包含每个的行：

java.lang.NullPointerException: Cannot execute null+null

控制器：

def activateSubscriptions (SubscriptionRequest subscriptionRequestInstance) {
    def temp
    println ("Params : $params.subscriptionRequestInstanceCheckBox , Count: $subscriptionRequestInstance.count()")

    params['subscriptionRequestInstanceCheckBox'].each  {
        temp =new Subscriptions(userId:subscriptionRequestInstance.userId,packageId:subscriptionRequestInstance.packageId,dasubscriptionRequestInstanceOfPackExp:subscriptionRequestInstance.dateCreated+30,balanceOfAds:Packages.get(subscriptionRequestInstance.packageId).numOfAds,
        balanceOfMsgs:Packages.get(subscriptionRequestInstance.packageId).numOfMsgs,balanceOfHR:Packages.get(subscriptionRequestInstance.packageId).numOfHR,balanceOfPages:Packages.get(subscriptionRequestInstance.packageId).numOfPages).save(flush:true)

        SubscriptionRequest.get(subscriptionRequestInstance.id).delete(flush:true)
    }
}

这是GSP：

<g:each in="${subscriptionRequestInstanceList}" status="i" var="subscriptionRequestInstance">
    <tr class="${(i % 2) == 0 ? 'even' : 'odd'}">
        <td>
            <g:checkBox checked="false" name='subscriptionRequestInstanceCheckBox' value="${subscriptionRequestInstance.id}"/> &nbsp;&nbsp; 
            <g:link action="show"  id="${subscriptionRequestInstance.id}">${fieldValue(bean: subscriptionRequestInstance, field: "userId")}</g:link>
        </td>
        <td>${fieldValue(bean: subscriptionRequestInstance, field: "packageId")}</td>
        <td><g:formatDate date="${subscriptionRequestInstance.dateCreated}" /></td>
    </tr>
</g:each>

虽然println的值为：

Params : [1, 2] , Count: 2

有什么想法吗？

Answer 1

构造函数中的这个语句看起来是个问题：

dasubscriptionRequestInstanceOfPackExp:subscriptionRequestInstance.dateCreated+30

如果目标只是修复例外，请将其更改为：

dasubscriptionRequestInstanceOfPackExp: (subscriptionRequestInstance.dateCreated ? subscriptionRequestInstance.dateCreated + 30 : null)

这假设dasubscriptionRequestInstanceOfPackExp字段可以为空，或者您可以保存失败。

不是一遍又一遍地使用Packages.get(subscriptionRequestInstance.packageId)，为什么不将它存储在这样的变量中呢？从性能的角度来看，它在这一点上可能毫无意义，但它会清除构造函数的参数。

def activateSubscriptions (SubscriptionRequest subscriptionRequestInstance) {
    def temp
    println ("Params : $params.subscriptionRequestInstanceCheckBox , Count: $subscriptionRequestInstance.count()")

    def package = Packages.get(subscriptionRequestInstance.packageId)

    params.subscriptionRequestInstanceCheckBox.each  {
        temp = new Subscriptions(
            userId: subscriptionRequestInstance.userId,
            packageId: subscriptionRequestInstance.packageId,
            dasubscriptionRequestInstanceOfPackExp: subscriptionRequestInstance.dateCreated + 30,
            balanceOfAds: package.numOfAds,
            balanceOfMsgs: package.numOfMsgs,
            balanceOfHR: package.numOfHR,
            balanceOfPages: package.numOfPages
        ).save(flush:true)

        SubscriptionRequest.get(subscriptionRequestInstance.id).delete(flush:true)
    }
}

Grails中的循环错误

1 个答案: