Entities and POJOs must have a usable public constructor in Kotlin

Question

I'm trying to make a Room entity by using @Ignore to a list but when i try to build the app i get the following error:

 Entities and POJOs must have a usable public constructor

Here is how my code looks like:

@Entity(tableName = "prodotti_table")
data class Prodotto(
    @PrimaryKey(autoGenerate = false)
    var codart: String,
    var desc: String,
    var prezzo_acq: Float,
    var prezzo_vend: Float,
    @Ignore var barcode: List<Barcode>,
    var qta: Float
)

@Entity(tableName = "barcode_prodotti_table")
data class Barcode(
    @PrimaryKey
    var id: Int,
    var codart: String,
    var barcode: String,
    var qta: Float
)

How can i solve it still by using the @Ignore in that data class?

score 1 · Accepted Answer · answered Jan 27 '21 at 16:15

You can't put an ignored property in the constructor, so do this:

@Entity(tableName = "prodotti_table")
data class Prodotto(
    @PrimaryKey(autoGenerate = false)
    var codart: String,
    var desc: String,
    var prezzo_acq: Float,
    var prezzo_vend: Float,
    var qta: Float
) {
    @Ignore var barcode: List<Barcode> = emptyList()
}

But remember that a property that isn't in the constructor of a data class will not participate in equals, hashcode, copy, or toString.

Entities and POJOs must have a usable public constructor in Kotlin

1 Answers1