kotlin - How to create instance of a data class for android Room which has fields with default values?

Question

Example:

@Entity(tableName = "data")
data class Data(@PrimaryKey(autoGenerate = true) val id: Int = 0,
                @ColumnInfo(name = "blob") val blob: ByteArray,
                @ColumnInfo(name = "timestamp", defaultValue = "(strftime('%s','now'))")
                val timetamp: String)
                 

How to create an instance of this class? I want to create it like this:

Data(blob = byteArrayOf(1,2,3))

I have found a way for this example using default parameter values(updated declaration below), but for ordinary fields, I don't know how to specify a not nullable value which will be considered as no value: I have tried ColumnInfo.VALUE_UNSPECIFED,"NULL","" but no luck with it.

@Entity(tableName = "data")
data class Data(@PrimaryKey(autoGenerate = true) val id: Int = 0,
                @ColumnInfo(name = "blob") val blob: ByteArray,
                @ColumnInfo(name = "timestamp")
                val timetamp: String = System.currentTimeMillis.toString())

Answer 1

You are close, put all the has-default-value parameters AT THE END, like this:

@Entity(tableName = "data")
data class Data(
    @ColumnInfo(name = "blob") 
    val blob: ByteArray,

    @PrimaryKey(autoGenerate = true) 
    val id: Int = 0,

    @ColumnInfo(name = "timestamp")
    val timetamp = System.currentTimeMillis()   //use Long type for time, recommended
)

Then you can just Data(byteArrayOf(1,2,3)).