fix: EXPOSED-263 Null arg parameter in exec() throws if logger enabled (

#1973)

The type for exec() parameterized arguments is declared as args: Iterable<Pair<IColumnType, Any?>>,
so passing null as the second element correctly sets the statement parameter to SQL NULL.
But if a logger is enabled, this exception is thrown:
java.lang.IllegalStateException: NULL in non-nullable column.
This is because all IColumnType default to being not nullable and fail the check
in `ColumnType.valueToString()` when attempting to parse the parameter value.

This exception can be avoided by always providing SQL NULL directly, via Op.nullOp<T>().
But given the type hints, the accepted parameter values should match what would
be accepted by any other DSL statement.

Even if the column in the Exposed table object is declared as being `nullable()`,
the column type in `exec()` has no knowledge of this because it is meant to accept
plain SQL using an anonymous Statement object.
This fix sets the nullable parameter of any column type in args to true so that
no exception will be thrown when the logger invokes valueToString().

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

@@ -206,7 +206,11 @@ open class Transaction(
 
             override fun prepareSQL(transaction: Transaction, prepared: Boolean): String = stmt
 
-            override fun arguments(): Iterable<Iterable<Pair<IColumnType, Any?>>> = listOf(args)
+            override fun arguments(): Iterable<Iterable<Pair<IColumnType, Any?>>> = listOf(
+                args.map { (columnType, value) ->
+                    columnType.apply { nullable = true } to value
+                }
+            )
         })
     }
 

exposed-tests/src/test/kotlin/org/jetbrains/exposed/sql/tests/shared/ParameterizationTests.kt

@@ -10,10 +10,11 @@ import org.jetbrains.exposed.sql.transactions.transaction
 import org.junit.Assume
 import org.junit.Test
 import kotlin.test.assertNotNull
+import kotlin.test.assertNull
 
 class ParameterizationTests : DatabaseTestsBase() {
     object TempTable : Table("tmp") {
-        val name = varchar("foo", 50)
+        val name = varchar("foo", 50).nullable()
     }
 
     private val supportMultipleStatements by lazy {
@@ -146,4 +147,19 @@ class ParameterizationTests : DatabaseTestsBase() {
 
         TransactionManager.closeAndUnregister(db)
     }
+
+    @Test
+    fun testNullParameterWithLogger() {
+        withTables(TempTable) {
+            // the logger is left in to test that it does not throw IllegalStateException with null parameter arg
+            addLogger(StdOutSqlLogger)
+
+            exec(
+                stmt = "INSERT INTO ${TempTable.tableName} (${TempTable.name.name}) VALUES (?)",
+                args = listOf(VarCharColumnType() to null)
+            )
+
+            assertNull(TempTable.selectAll().single()[TempTable.name])
+        }
+    }
 }

exposed-tests/src/test/kotlin/org/jetbrains/exposed/sql/tests/shared/ddl/SequencesTests.kt

@@ -86,7 +86,6 @@ class SequencesTests : DatabaseTestsBase() {
     fun `test insert LongIdTable with auth-increment with sequence`() {
         withDb {
             if (currentDialectTest.supportsSequenceAsGeneratedKeys) {
-                addLogger(StdOutSqlLogger)
                 try {
                     SchemaUtils.create(DeveloperWithAutoIncrementBySequence)
                     val developerId = DeveloperWithAutoIncrementBySequence.insertAndGetId {