grails - 保存 Grails GORM/Domain 类会导致 `NullPointerException`

Question

我有一项服务，负责在成功填写注册页面后创建相关帐户层次结构:

    def userRole = Role.findByAuthority("ROLE_USER")
    final account = new Account(email: command.email, password: command.password)
    account.save(flush: true)

    final publisher = new Publisher(name: command.name) //, account: account)
    publisher.save(flush: true)

    final accountRole = AccountRole.create account, userRole

无论我做什么，AccountRole.create account, userRole 都会在这一行失败:

static AccountRole create(Account account, Role role) {
    def instance = new AccountRole(account: account, role: role)
    instance.save()  // throws NullPointerException
    instance
}

我尝试过new AccountRole(account: account, role: userRole)，但是当我手动调用save时，这也失败了。 Account 和 AccountRole 是由 Grails 3 Spring Security 插件生成(并稍作调整)的类。

以下是失败的 AccountRole.create(...) 调用的堆栈跟踪:

java.lang.reflect.InvocationTargetException: null
    at grails.plugin.springsecurity.web.UpdateRequestContextHolderExceptionTranslationFilter.doFilter(UpdateRequestContextHolderExceptionTranslationFilter.groovy:64)
    at grails.plugin.springsecurity.web.filter.GrailsAnonymousAuthenticationFilter.doFilter(GrailsAnonymousAuthenticationFilter.groovy:53)
    at grails.plugin.springsecurity.web.authentication.logout.MutableLogoutFilter.doFilter(MutableLogoutFilter.groovy:62)
    at grails.plugin.springsecurity.web.SecurityRequestHolderFilter.doFilter(SecurityRequestHolderFilter.groovy:58)
    at grails.plugin.springsecurity.web.filter.DebugFilter.invokeWithWrappedRequest(DebugFilter.groovy:102)
    at grails.plugin.springsecurity.web.filter.DebugFilter.doFilter(DebugFilter.groovy:69)
    at grails.plugin.springsecurity.web.UpdateRequestContextHolderExceptionTranslationFilter.doFilter(UpdateRequestContextHolderExceptionTranslationFilter.groovy:64)
    at grails.plugin.springsecurity.web.filter.GrailsAnonymousAuthenticationFilter.doFilter(GrailsAnonymousAuthenticationFilter.groovy:53)
    at grails.plugin.springsecurity.web.authentication.logout.MutableLogoutFilter.doFilter(MutableLogoutFilter.groovy:62)
    at grails.plugin.springsecurity.web.SecurityRequestHolderFilter.doFilter(SecurityRequestHolderFilter.groovy:58)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException: null
    at package.AccountRole.create(AccountRole.groovy:48)
    at package.RegistrationService.$tt__handleNewRegistration(RegistrationService.groovy:25)

版本信息:

| Grails Version: 3.1.5
| Groovy Version: 2.4.6
| JVM Version: 1.8.0_73

请救我脱离痛苦!我现在已经花了几个小时了:(

Answer 1

没有足够的信息可以确定，但 instance 不太可能为 null，因为您刚刚使用构造函数调用创建了它，但您应该检查一下以确保，例如

static AccountRole create(Account account, Role role) {
   def instance = new AccountRole(account: account, role: role)
   println "instance null? ${instance == null}"
   instance.save()  // throws NullPointerException
   instance
}

更有可能的是验证期间的问题导致了异常，所以我的猜测是 userRole 或 account 出现问题。检查 userRole 是否已正确检索，并且帐户 save() 调用中不存在验证错误:

def account = new Account(email: command.email, password: command.password)
account.save(flush: true)
if (account.hasErrors()) {
   log.warn "Failed to save Account $account: $account.errors"
}