CODEWITHSUNDEEP
androidkotlinmoshi
zerstoer
zerstoer

Reputation: 115

Moshi PolymorphicJsonAdapterFactory

I'm using Moshi for an Android App, but when the payload change for any reason, example: the backend add a new object type, the app will crash because I need to tell Moshi to get this new object type.

return Moshi.Builder()
    .add(Adapter1())
    .add(PolymorphicJsonAdapterFactory
            .of(BaseClass::class.java, "baseclass")
            .withSubtype(EntityOne::class.java, "entityone")
            .withSubtype(EntityTwo::class.java, "entitytwo")
    )
    .build()

All works well, but if a new entity is coming inside the payload, the app won't show any data.

Example: an "entitythree" is added, to avoid the app stop showing info, I need to come and add

.withSubtype(EntityThree::class.java, "entitythree")

How can I avoid this behaviour, if the payload add new entities, nothing happen and the app will continue working well?

Thanks in advance

Upvotes: 2

Views: 1275

Answers (1)

Dat Pham Tat
Dat Pham Tat

Reputation: 1463

Have a class denoting an unknown entity:

data class UnknownEntity : BaseClass {
    val baseclass: String = "unknown"
}

Then, add to your factory:

PolymorphicJsonAdapterFactory
            .of(BaseClass::class.java, "baseclass")
            .withSubtype(EntityOne::class.java, "entityone")
            .withSubtype(EntityTwo::class.java, "entitytwo")
            .withDefaultValue(UnknownEntity())

Then in the rest of your logic, where you manipulate with the acquired entities, just ignore the UnknownEntity instances, and the app should work as before.

Upvotes: 4

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