将Parceler与带有构造函数的Kotlin数据类一起用于序列化 [英] Use of Parceler with Kotlin data class with constructor for serialization

问题描述

有没有一种方法可以对Kotlin数据类和构造函数使用 Parceler 进行序列化，而无需为每个字段使用@ParcelProperty批注?

Is there a way to use Parceler with Kotlin data classes and constructor for serialization without using @ParcelProperty annotation for each field?

如果我尝试使用像这样的库:

If I try and use library like this:

@Parcel
data class Valve @ParcelConstructor constructor(val size: Int)

我得到Error:Parceler: No corresponding property found for constructor parameter arg0.但是，如果我添加@ParcelProperty("size")，它就可以正常工作.
为什么会这样?

I get Error:Parceler: No corresponding property found for constructor parameter arg0. But if I add @ParcelProperty("size") it works just fine.
Why is that?

更新:
还有其他使用此库的方法.
我可以只删除@ParcelConstructor批注，但随后会出现错误
Error:Parceler: No @ParcelConstructor annotated constructor and no default empty bean constructor found.
我认为(未经测试)我也可以使所有构造函数参数为可选参数并添加@JvmOverloads，但这具有副作用，我必须检查该类的所有属性是否为空.

Update:
There are other another way to use this library.
I could just remove @ParcelConstructor annotation, but then I will get error
Error:Parceler: No @ParcelConstructor annotated constructor and no default empty bean constructor found.
I think (haven't tested it) I also could make all constructor parameters optional and add @JvmOverloads but that has a side effect that I have to check all properties of the class if they are null or not.

更新2 :
这对我有用:

Update 2:
This is what worked for me:

@Parcel
data class Valve(val size: Int? = null)

简而言之，生成的Java类必须具有默认的空构造函数.一种实现上述目的的方法是-所有变量都应具有默认值.

In short generated Java class must have default empty constructor. One way to achieve that is to do as above - all variables should have default values.

推荐答案

根据文档，默认情况下，Parceler适用于公共字段.但是通常的Kotlin data class(如您的示例所示)实际上是传统的getter/setter bean"，因为每个Kotlin属性都由一个私有字段和一个getter/[setter]表示.

According to the docs, Parceler by default works with public fields. But a usual Kotlin data class (as in your example) is rather a "traditional getter/setter bean", since every Kotlin property is represented by a private field and a getter/[setter].

TL; DR:我认为这会起作用:

TL; DR: I think this will work:

@Parcel(Serialization.BEAN)
data class Valve(val size: Int = 10)

请注意默认值，它允许Kotlin自动生成一个额外的空构造函数，这是Java Been规范所必需的.

Note the default value, it allows Kotlin to automatically generate an additional empty constructor, which is required by the Java Been specification.

另一种方法是标记我们已经拥有的构造函数:

Another way would be to mark the constructor that we already have:

@Parcel(Serialization.BEAN)
data class Driver @ParcelConstructor constructor(val name: String)

特定文档: https://github.com/johncarl81/parceler#gettersetter-serialization

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