Lack of nullable values in anko-db

[dstd]

It's not possible to pass null values into insert, replace, update, where and probably several other methods, because they use Pair<String, Any>. So there's no straight way to set some column to null. Probably they should use Pair<String, Any?> for values.

[PaulWoitaschek]

+1.

Also the row parser throws an exception if a type is nullable and you specify it as nullable. Then it throws an exception that for example Unit cant be converted to String?.

[dstd]

SqlParsers.kt

private fun Cursor.getColumnValue(index: Int): Any? {
    if (isNull(index)) return null

    return when (getType(index)) {
        Cursor.FIELD_TYPE_INTEGER -> getLong(index)
        Cursor.FIELD_TYPE_FLOAT -> getDouble(index)
        Cursor.FIELD_TYPE_STRING -> getString(index)
        Cursor.FIELD_TYPE_BLOB -> getBlob(index)
        else -> Unit
    }
}

@yanex I'm not sure why Unit is used here. But if the column's value is null, then getType will not return a correct type, and this Unit will cause the java.lang.ClassCastException in org.jetbrains.anko.db.rowParser.parseRow (in generated SqlParserHelpers.kt).

In my project I made these null-safe wrappers to workaround this issue:

fun Any.nonUnit() = if (this is Unit) null else this

fun <T1, T2, R> rowSafeParser(parser: (T1, T2) -> R): RowParser<R> {
    return object : RowParser<R> {
        override fun parseRow(columns: Array<Any>): R {
            if (columns.size != 2)
                throw SQLiteException("Invalid row: 2 columns required")
            @Suppress("UNCHECKED_CAST")
            return parser(columns[0].nonUnit() as T1, columns[1].nonUnit() as T2)
        }
    }
}