Question

如果我将Payment.kt和CartPayment.kt中的lateinit var id: String更改为var id: String? = ""，就可以正常工作，但是问题是我希望输入ID，如何实现？ >

错误：

java.lang.RuntimeException: Unable to create application: io.realm.exceptions.RealmMigrationNeededException: Migration is required due to the following errors:
    - Property 'CartPayment.id' has been made required.
    - Property 'Payment.id' has been made required.

型号：

open class Payment() : RealmObject() {

    @PrimaryKey
    lateinit var id: String
    var typeValue: Int = 0
    var statusValue: Int = 0
    var value: Double = 0.0
    var referenceNumber: String? = null

注意：付款和CartPayment模型相同，除了类名

Migration.kt

class Migration : RealmMigration {

    override fun migrate(realm: DynamicRealm, oldVersion: Long, newVersion: Long) {
        var oldVersion = oldVersion
        val schema = realm.schema

        if (oldVersion == 0L) {
            schema.create("Payment")
                .addField("id", String::class.java, FieldAttribute.PRIMARY_KEY)
                .addField("typeValue", Int::class.java)
                .addField("statusValue", Int::class.java)
                .addField("value", Double::class.java)
                .addField("referenceNumber", String::class.java)
            schema.get("Order")!!
                .addRealmListField("payments", schema.get("Payment")!!)
            oldVersion++
        }

        if (oldVersion == 1L) {
            schema.create("CartPayment")
                .addField("id", String::class.java, FieldAttribute.PRIMARY_KEY)
                .addField("typeValue", Int::class.java)
                .addField("statusValue", Int::class.java)
                .addField("value", Double::class.java)
                .addField("referenceNumber", String::class.java)
            schema.get("Order")!!
                .addField("cashPaymentAmount", Float::class.java)
                .addField("change", Float::class.java)
            oldVersion++
        }

    }
}

App.kt

class App: Application() {

    override fun onCreate() {
        super.onCreate()

        Realm.init(this)

        val realmConfig = RealmConfiguration.Builder()
            .schemaVersion(2)
            .migration(Migration())
            .build()
        Realm.getInstance(realmConfig)
        Realm.setDefaultConfiguration(realmConfig)

        Fresco.initialize(this)
    }
}

Answer 1

基本上，您要添加一个新字段“ id”，它是主键（因此是必需的键）。如果您在初始化（lateinit）时未指定任何值，那么领域将如何迁移所有没有ID但在迁移后需要的早期记录？因此是错误。

以下解决方案可能有效

要么预先填充ID（无需使用lateinit）
将您之前的记录转换为没有ID的记录

查看官方示例here

Answer 2

.addField("id", String::class.java, FieldAttribute.PRIMARY_KEY, FieldAttribute.REQUIRED) 做到了。

如果您声明变量为lateinit，请确保添加FieldAttribute.REQUIRED。

由于需要提供物业ID，因此需要进行迁移

2 个答案: