android - Android Kotlin：领域多对一关系

Question

我在使用 Realm 管理 Kotlin 对象之间的一对多关系时遇到了麻烦。我不明白如何进行一些插入或更新。

这里我的两个对象与考试和职业之间存在一对多的关系。

open class Career : RealmObject() {

    @PrimaryKey
    var id: Long = 1
    var status: String = CareerStatus.ACTIVE.value
    var careerName: String? = null
    var exams: RealmList<Exam>? = null
}

open class Exam : RealmObject() {

    @PrimaryKey
    var id: Long = 1
    var teachers: String? = null
    var lode: Boolean? = null
    var score: String = ""
    var exam: String = ""
    var examDescription: String? = null
    var date: Date = Date()
    var cfu: Long = Long.MIN_VALUE
    @LinkingObjects("exams")
    val career: RealmResults<Career>? = null
}

这里的两个类 Manager 管理 Realm 上的读/写

class CareerManager : DatabaseManager() {
    fun findActiveCareer(): Career? {
        return realm.where(Career::class.java).equalTo("status", CareerStatus.ACTIVE.value).findFirst()
    }

    fun insertExamInCareer(exam: Exam) {
        realm.executeTransaction {
            var activeCareer: Career = findActiveCareer()
                    ?: throw Resources.NotFoundException("No active career found")

            activeCareer.exams?.add(exam)
            realm.copyToRealmOrUpdate(exam)
        }
    }

    fun closeActiveCareer() {
        realm.executeTransaction {
            val activeCareer: Career = findActiveCareer()
                    ?: throw Resources.NotFoundException("No active career found")

            activeCareer.status = CareerStatus.TERMINATED.value
        }
    }
}

class ExamManager : DatabaseManager() {

    fun findAll(): List<Exam> {
        val findAll = realm.where(Exam::class.java).findAll()

        return realm.copyFromRealm(findAll).toList()
    }

    fun findAllActive(): List<Exam> {
        val findAll = realm.where(Exam::class.java).equalTo("career.status", CareerStatus.ACTIVE.value).findAll()

        return realm.copyFromRealm(findAll).toList()
    }

    fun insert(exam: Exam): Long {
        realm.beginTransaction()
        var newId: Long = 1

        if (realm.where(Exam::class.java).max("id") != null) {
            newId = realm.where(Exam::class.java).max("id") as Long + 2
        }

        val examToSave = realm.createObject(Exam::class.java, newId)
        examToSave.exam = exam.exam
        examToSave.examDescription = exam.examDescription
        examToSave.date = exam.date
        examToSave.teachers = exam.teachers
        examToSave.score = exam.score
        examToSave.lode = exam.lode
        examToSave.cfu = exam.cfu

        realm.commitTransaction()

        CareerManager().updateCareerExam(findAll())

        return newId

    }
}

在我的应用程序中，我需要在我的职业生涯中插入一些实际上处于 ACTIVE 状态的考试。对于插入，我使用CareerManager().insertExamInCareer(exam)这个调用（在我尝试使用ExamManager().insert(exam)但不起作用之前）。

另一个用例是当我需要关闭一个职业并将考试添加到另一个职业时。我以这种方式这样做

CareerManager().closeActiveCareer()

CareerManager().createCareer()

CareerManager().insertExamInCareer(考试)

两个职业的考试是一样的，但他们必须不同，在考试中必须有两个记录，而不是一个

标签： androidkotlinrealm