What's wrong with Room Database on Kotlin?

Question

I have a data class

@Entity(tableName = "type")
data class Type(
    @PrimaryKey(autoGenerate = true) var id: Int = 0,
    var type: Int = 0
)

When compiling project I receive message

Error:Room cannot pick a constructor since multiple constructors are suitable.

But if I change data class to

@Entity(tableName = "type")
data class Type(
    @PrimaryKey(autoGenerate = true) var id: Int = 0,
    var type: String = ""
)

or java class

@Entity(tableName = "type")
public class Type {
    @PrimaryKey(autoGenerate = true)
    private int id;
    private int type;
    // getters and setters
}

it works fine. Is it Kotlin bug or something else?

This is probably because Kotlin is generating multiple Java constructors for your Type class when you have default arguments. This seems to be related to the issue described [here](https://stackoverflow.com/questions/44620835/room-cannot-pick-a-constructor-since-multiple-constructors-are-suitable-error) — Dr. Nitpick, Jun 26 '17 at 13:23

score 0 · Answer 1 · answered Oct 06 '17 at 23:54

0

I do not know why this occurs, but if you use id? = 0 solves the problem, at least in the tests I did.

Android Studio Beta 7
ext.support_version = '26 .1.0 '
ext.kotlin_version = '1.1.51'
ext.anko_version = '0.10.1'
ext.archroom_version = '1.0.0-alpha9-1'

    @Entity(tableName = "type")
    data class Type(
            @PrimaryKey(autoGenerate = true) var id: Int? = 0,
            var type: Int = 0
    )

answered Oct 06 '17 at 23:54

PCésar

11
2

1

This hapens because when you create the object it should have a null primary key, this only gets filled when you insert it into the database. I think you should default it to null, otherwise Room will probably update index 0 instead of inserting. – deive Jan 10 '18 at 14:17

What's wrong with Room Database on Kotlin?

1 Answers1