Refine BiCompositeColumn generics

exposed-core/src/main/kotlin/org/jetbrains/exposed/sql/CompositeColumn.kt

@@ -35,8 +35,8 @@ abstract class CompositeColumn<T> : Expression<T>() {
 abstract class BiCompositeColumn<C1, C2, T>(
     protected val column1: Column<C1>,
     protected val column2: Column<C2>,
-    val transformFromValue: (T) -> Pair<C1?, C2?>,
-    val transformToValue: (Any?, Any?) -> T
+    val transformToValue: (C1, C2) -> T,
+    val transformFromValue: (T) -> Pair<C1, C2>
 ) : CompositeColumn<T>() {
 
     override fun getRealColumns(): List<Column<*>> = listOf(column1, column2)
@@ -50,12 +50,14 @@ abstract class BiCompositeColumn<C1, C2, T>(
     }
 
     override fun restoreValueFromParts(parts: Map<Column<*>, Any?>): T {
-        val v1 = parts[column1]
-        val v2 = parts[column2]
+        @Suppress("UNCHECKED_CAST")
+        val v1 = parts[column1] as C1
+        @Suppress("UNCHECKED_CAST")
+        val v2 = parts[column2] as C2
         val result = transformToValue(v1, v2)
-        check(result != null || nullable) {
+        require(result != null || nullable) {
             "Null value received from DB for non-nullable ${this::class.simpleName} column"
         }
-        return result as T
+        return result
     }
 }

exposed-money/src/main/kotlin/org/jetbrains/exposed/sql/money/CompositeMoneyColumn.kt

@@ -20,22 +20,18 @@ class CompositeMoneyColumn<T1 : BigDecimal?, T2 : CurrencyUnit?, R : MonetaryAmo
         column1 = amount,
         column2 = currency,
         transformFromValue = { money ->
-            val amountValue = money?.number?.numberValue(BigDecimal::class.java) as? T1
-            val currencyValue = money?.currency as? T2
+            val amountValue = money?.number?.numberValue(BigDecimal::class.java) as T1
+            val currencyValue = money?.currency as T2
             amountValue to currencyValue
         },
         transformToValue = { amountVal, currencyVal ->
             if (amountVal == null || currencyVal == null) {
                 null as R
             } else {
-                val result = Monetary.getDefaultAmountFactory().setNumber(amountVal as Number)
-
-                when (currencyVal) {
-                    is CurrencyUnit -> result.setCurrency(currencyVal)
-                    is String -> result.setCurrency(currencyVal)
-                }
-
-                result.create() as R
+                Monetary.getDefaultAmountFactory().run {
+                    setNumber(amountVal)
+                    setCurrency(currencyVal)
+                }.create() as R
             }
         }
     )

exposed-money/src/main/kotlin/org/jetbrains/exposed/sql/money/CompositeMoneyColumnType.kt

@@ -1,6 +1,7 @@
 package org.jetbrains.exposed.sql.money
 
 import org.jetbrains.exposed.sql.Column
+import org.jetbrains.exposed.sql.CompositeColumn
 import org.jetbrains.exposed.sql.Table
 import java.math.BigDecimal
 import javax.money.CurrencyUnit
@@ -23,5 +24,7 @@ fun Table.compositeMoney(amountColumn: Column<BigDecimal?>, currencyColumn: Colu
         if (amountColumn !in columns && currencyColumn !in columns) {
             registerCompositeColumn(it)
         }
+        // Set CompositeColumn.nullable = true
+        (it as CompositeColumn<MonetaryAmount>).nullable()
     }
 }

exposed-money/src/test/kotlin/org/jetbrains/exposed/sql/money/MoneyDefaultsTest.kt

@@ -22,25 +22,27 @@ class MoneyDefaultsTest : DatabaseTestsBase() {
         val field = varchar("field", 100)
         val t1 = compositeMoney(10, 0, "t1").default(defaultValue)
         val t2 = compositeMoney(10, 0, "t2").nullable()
+
+        val price_amount = decimal("price_amount", 10, 0).nullable()
+        val price_currency = currency("price_currency").nullable()
+        val price = compositeMoney(price_amount, price_currency) /* it is implicitly nullable since price_amount is nullable */
+
         val clientDefault = integer("clientDefault").clientDefault { cIndex++ }
     }
 
     class DBDefault(id: EntityID<Int>) : IntEntity(id) {
         var field by TableWithDBDefault.field
         var t1 by TableWithDBDefault.t1
         var t2 by TableWithDBDefault.t2
+        var price by TableWithDBDefault.price
         val clientDefault by TableWithDBDefault.clientDefault
 
         override fun hashCode(): Int = id.value.hashCode()
 
         override fun equals(other: Any?): Boolean {
             if (this === other) return true
             if (other !is DBDefault) return false
-            if (other.t1 != other.t1) return false
-            if (other.t2 != other.t2) return false
-            if (other.clientDefault != other.clientDefault) return false
-
-            return true
+            return id.value == other.id.value
         }
 
         companion object : IntEntityClass<DBDefault>(TableWithDBDefault)
@@ -94,4 +96,19 @@ class MoneyDefaultsTest : DatabaseTestsBase() {
             assertEquals(TableWithDBDefault.defaultValue, db1.t1)
         }
     }
+
+    @Test
+    fun testImplicitlyNullableCompositeColumnType() {
+        withTables(TableWithDBDefault) {
+            TableWithDBDefault.cIndex = 0
+            val db1 = DBDefault.new { field = "1" }
+            flushCache()
+            assertNull(db1.price, "db1.price should be null since it was not set when calling new")
+            val money = Money.of(BigDecimal.ONE, "USD")
+            db1.price = money
+            db1.refresh(flush = true)
+            assertEquals(money, db1.t1)
+            assertEquals(TableWithDBDefault.defaultValue, db1.t1)
+        }
+    }
 }