删除的项目影响分页

Question

我需要迭代大量用户（10000k+），并在每个用户处理一些逻辑，例如检查用户是否符合我的删除条件，如果是，则发送电子邮件并删除数据库中的用户。

这是我的代码想法，但我面临一些问题。如果我删除用户，则分页会受到影响。我尝试总是从 0 开始分页，但如果某些用户无法处理，那么我的代码就会陷入无限循环。你能帮我如何有效地解决这个问题吗？

@Service
class UserService(private val userRepository: UserRepository, private val emailService: EmailService) {

    fun processInactiveExternalUsersInBatches(pageSize: Int) {
        var page = 0
        var usersPage: Page<User>

        do {
            usersPage = userRepository.findUsersByType(userType = UserType.EXTERNAL_USER, PageRequest.of(page, pageSize))
            processUsers(usersPage.content)

            page++
        } while (usersPage.hasNext())
    }

    private fun processUsers(users: List<User>) {
        for (user in users) {
            if (!user.active) {
                // Send an email to the user about deactivation
                emailService.sendDeactivationEmail(user)

                // Delete the user using the repository
                userRepository.delete(user)
            }
        }
    }
}

Answer 1

您可以处理用户并向他们发送电子邮件，但不能删除它们，然后您可以将它们存储在列表中，并在 processInactiveExternalUsersInBatches 结束时删除它们。请注意，我用java修改了你的代码，但我希望你能得到像这样的解决方案：

    @Service
    class UserService(private val userRepository: UserRepository, private val 
    emailService: EmailService) {

    fun processInactiveExternalUsersInBatches(pageSize: Int) {
        var page = 0
        var usersPage: Page<User>

        **var deletedUsers = new ArrayList<User>();**

        do {
            usersPage = userRepository.findUsersByType(userType = 
            UserType.EXTERNAL_USER, PageRequest.of(page, pageSize))
            **var usersToBeDeleted =** processUsers(usersPage.content)
        
            **deletedUsers.addAll(usersToBeDeleted);**

            page++
        } while (usersPage.hasNext())

        **userRepository.deleteAll(deletedUsers);**
    }

    private **List<User>** fun processUsers(users: List<User>) {
        **var deletedUsers = new ArrayList<User>();**
        for (user in users) {
            if (!user.active) {
                // Send an email to the user about deactivation
                emailService.sendDeactivationEmail(user)

                // find deleted users and return them
                **deletedUsers.add(user)**
            }
        }
        **return deletedUsers;**
    }
}