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androidkotlinandroid-roomparcelablekotlin-android-extensions

How to parcelise member variable other than constructor in data class while using @Parcelize


I am using Room and Kotlin data class. Such as,

@Entity(tableName = "Person")
@Parcelize
class Test(@ColumnInfo(name = "name") var name:String) : Parcelable{
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "ID")
    var id: Long? = null
}

I can create the instance using the constructor and insert the data. I am also getting a warning "property would not be serialized into a 'parcel'". When I was trying to send the object through a bundle, the id is missing, which is expected as the warning says so. How can I add that member ID in the parcel? I am not keeping the ID in the constructor as I want them to be generated automatically.


Solution

  • You can find this information with the documentation:

    @Parcelize requires all serialized properties to be declared in the primary constructor. Android Extensions will issue a warning on each property with a backing field declared in the class body. Also, @Parcelize can't be applied if some of the primary constructor parameters are not properties.

    If your class requires more advanced serialization logic, you can write it inside a companion class:

    @Parcelize
    data class User(val firstName: String, val lastName: String, val age: Int) : Parcelable {
        private companion object : Parceler<User> {
            override fun User.write(parcel: Parcel, flags: Int) {
                // Custom write implementation
            }
    
            override fun create(parcel: Parcel): User {
                // Custom read implementation
            }
        }
    }