java - 带有 Kotlin 数据类的 ArangoDB Java 驱动程序

Question

好吧，Arongo DB Java 驱动程序在存储 Kotlin 数据类时没有问题，但它无法将它们加载回来。

展示:

import com.arangodb.ArangoCollection
import com.arangodb.ArangoDB
import com.arangodb.entity.DocumentCreateEntity

fun main(args: Array<String>) {
    // Get or recreate collection: "some_collection" in DB "test_db"
    val collection: ArangoCollection = with(ArangoDB.Builder().build()!!.db("test_db")) {
        if (!exists()) create()
        with(collection("some_colelction")) {
            if (!exists()) create()
            this
        }
    }

    // POJO as Kotlin data class
    data class Foo(
            val topic: String,
            val answer: Int
    )

    val result: DocumentCreateEntity<Foo> = collection.insertDocument(Foo("The ultimate answer", 42))

    // reusult have a key of the new document
    // And in ArangoDB Web Interface you can see this document: {"answer":42,"topic":"The ultimate answer"}
    // http://localhost:8529/_db/test_db/_admin/aardvark/index.html#collection/some_colelction/documents/

    // But it doesn't work backwards
    val foo: Foo = collection.getDocument(result.key, Foo::class.java)
}

堆栈跟踪:

Exception in thread "main" com.arangodb.ArangoDBException: com.arangodb.velocypack.exception.VPackParserException: java.lang.InstantiationException: MainKt$main$Foo
    at com.arangodb.internal.util.ArangoDeserializerImpl.deserialize(ArangoDeserializerImpl.java:59)
    at com.arangodb.internal.util.ArangoUtilImpl.deserialize(ArangoUtilImpl.java:58)
    at com.arangodb.internal.ArangoExecutor.createResult(ArangoExecutor.java:112)
    at com.arangodb.internal.ArangoExecutorSync$1.deserialize(ArangoExecutorSync.java:56)
    at com.arangodb.internal.ArangoExecutorSync.execute(ArangoExecutorSync.java:72)
    at com.arangodb.internal.ArangoExecutorSync.execute(ArangoExecutorSync.java:53)
    at com.arangodb.internal.ArangoExecutorSync.execute(ArangoExecutorSync.java:49)
    at com.arangodb.internal.ArangoCollectionImpl.getDocument(ArangoCollectionImpl.java:134)
    at com.arangodb.internal.ArangoCollectionImpl.getDocument(ArangoCollectionImpl.java:126)
    at MainKt.main(main.kt:30)
Caused by: com.arangodb.velocypack.exception.VPackParserException: java.lang.InstantiationException: MainKt$main$Foo
    at com.arangodb.velocypack.VPack.deserialize(VPack.java:398)
    at com.arangodb.internal.util.ArangoDeserializerImpl.deserialize(ArangoDeserializerImpl.java:55)
    ... 9 more
Caused by: java.lang.InstantiationException: MainKt$main$Foo
    at java.lang.Class.newInstance(Class.java:427)
    at com.arangodb.velocypack.VPack.createInstance(VPack.java:488)
    at com.arangodb.velocypack.VPack.deserializeObject(VPack.java:450)
    at com.arangodb.velocypack.VPack.getValue(VPack.java:569)
    at com.arangodb.velocypack.VPack.deserialize(VPack.java:396)
    ... 10 more
Caused by: java.lang.NoSuchMethodException: MainKt$main$Foo.<init>()
    at java.lang.Class.getConstructor0(Class.java:3082)
    at java.lang.Class.newInstance(Class.java:412)
    ... 14 more

Kotlin 的数据类很好地序列化为预期的 JSON 文档，但似乎 ArangoDB Java 驱动程序无法将它们加载回来。如果我将文档作为 BaseDocument 获取，我可以毫无问题地使用一些 JSON 库将其映射回我的数据类，但是加油!必须有更好的方法，否则我肯定错过了一些东西。

Answer 1

ArangoDB Java 驱动程序支持替代序列化程序来反序列化文档、边缘和查询结果。一种实现是 VelocyJack这是基于 jackson 与 jackson-dataformat-velocypack 的合作.

您应该能够配置它，它与 jackson-kotlin-module 一起工作.

VelocyJack velocyJack = new VelocyJack();
velocyJack.configure((mapper) -> {
  mapper.registerModule(new KotlinModule())
});
ArangoDB arango = new ArangoDB.Builder().serializer(velocyJack).build();