Kotlin：ObjectBox和kotlinx.Serialization的组合实体类有冲突吗？

Question

I'm using kotlinx.serialization to parse JSON from an API and ObjectBox as a local storage.

Both libraries allow structuring model or entity classes. I'd like to avoid redundant classes and prefer to combine them into one entity class each.

It worked fine until I had to add relations .

I'd like to accept everything from the API, that's why every field is @Optional . The validation is made on the ObjectBox part of the entity.

Below you can find the desired code, which is not working.

1st problem: @Optional fields need to have a default value. After adding ? = null ? = null (which felt dirty), I got to the

2nd problem: after parsing and storing, the following error appears:

java.lang.NoSuchMethodError: No direct method (Lkotlin/reflect/KClass;Lkotlinx/serialization/KSerializer;)V in class Lkotlinx/serialization/ContextSerializer; or its super classes (declaration of 'kotlinx.serialization.ContextSerializer' appears in /data/app/com.acme.myapp2A1fXerVu==/split_lib_dependencies_apk.apk)

Entity: AppleTree

@Entity // ObjectBox
@Serializable // Serializable
data class AppleTree(

    @Optional // Serializable
    @Id(assignable=true) // ObjectBox
    var id: Long = 0,

    @Optional // Serializable
    @Backlink // ObjectBox    
    var apples: ToMany<Apple>
)

Entity: Apple

@Entity 
@Serializable 
data class Apple(

    @Optional // Serializable
    @Id(assignable=true) // ObjectBox
    var id: Long = 0,

    @Optional // Serializable
    var tree: ToOne<AppleTree>     
)

Fetch & store

private fun fetch() {
  doAsync {
      var json = mapKeys(URL(myURL).readText()) // fetch JSON from API
      uiThread {
          val appleTree = JSON.nonstrict.parse<AppleTree>(json) // parse JSON
          val appleTreeBox = (application as App).getAppleTreeBox() // get ObjectBox
          appleTreeBox.put(appleTree) // save
      }
  }
}

Any idea?

Thank you in advance!

Answer 1

I could not find a combined solution without conflicts, so I decided to split the models:

1. Each API call for Retrofit 2
2. Model for each ObjectBox entity

I create ObjectBox entities after fetching the data from Retrofit. A bit too much redundancy, but it works. :-)

Answer 2

I just saw this solution and wrote an article about how to do this simply without mapping Entities.

I hope this might assist you -> https://medium.com/@ryan.shaw_80293/android-local-database-tricks-with-kotlin-and-objectbox-f0da58c9d5a3