fix: EXPOSED-389 Coalesce operator returning nullable value (#2107)

The Coalesce function was returning a nullable type when it shouldn't. (cherry picked from commit ff613fa)
JetBrains · Jun 3, 2024 · 184c7ec · 184c7ec
1 parent f97820f
commit 184c7ec
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Showing 3 changed files with 17 additions and 9 deletions.
diff --git a/exposed-core/src/main/kotlin/org/jetbrains/exposed/sql/Function.kt b/exposed-core/src/main/kotlin/org/jetbrains/exposed/sql/Function.kt
@@ -438,11 +438,12 @@ class CaseWhenElse<T>(
 /**
  * Represents an SQL function that returns the first of its arguments that is not null.
  */
-class Coalesce<out T, S : T?>(
+@Suppress("UNCHECKED_CAST")
+class Coalesce<T, S : T?>(
  private val expr: ExpressionWithColumnType<S>,
  private val alternate: Expression<out T>,
  private vararg val others: Expression<out T>
-) : Function<S>(expr.columnType) {
+) : Function<T>(expr.columnType as IColumnType<T & Any>) {
  override fun toQueryBuilder(queryBuilder: QueryBuilder): Unit = queryBuilder {
  (listOf(expr, alternate) + others).appendTo(
  prefix = "COALESCE(",

diff --git a/exposed-core/src/main/kotlin/org/jetbrains/exposed/sql/SQLExpressionBuilder.kt b/exposed-core/src/main/kotlin/org/jetbrains/exposed/sql/SQLExpressionBuilder.kt
@@ -817,7 +817,7 @@ interface ISqlExpressionBuilder {
  expr: ExpressionWithColumnType<S>,
  alternate: Expression<out T>,
  vararg others: Expression<out T>
- ): Coalesce<T?, S> = Coalesce(expr, alternate, others = others)
+ ): Coalesce<T, S> = Coalesce<T, S>(expr, alternate, others = others)
 
  /**
  * Compares [value] against any chained conditional expressions.

diff --git a/...-tests/src/test/kotlin/org/jetbrains/exposed/sql/tests/shared/functions/FunctionsTests.kt b/...-tests/src/test/kotlin/org/jetbrains/exposed/sql/tests/shared/functions/FunctionsTests.kt
@@ -2,6 +2,7 @@ package org.jetbrains.exposed.sql.tests.shared.functions
 
 import org.jetbrains.exposed.dao.id.IntIdTable
 import org.jetbrains.exposed.sql.*
+import org.jetbrains.exposed.sql.SqlExpressionBuilder.coalesce
 import org.jetbrains.exposed.sql.SqlExpressionBuilder.concat
 import org.jetbrains.exposed.sql.tests.DatabaseTestsBase
 import org.jetbrains.exposed.sql.tests.TestDB
@@ -10,7 +11,11 @@ import org.jetbrains.exposed.sql.tests.shared.assertEqualCollections
 import org.jetbrains.exposed.sql.tests.shared.assertEquals
 import org.jetbrains.exposed.sql.tests.shared.dml.DMLTestsData
 import org.jetbrains.exposed.sql.tests.shared.dml.withCitiesAndUsers
-import org.jetbrains.exposed.sql.vendors.*
+import org.jetbrains.exposed.sql.vendors.H2Dialect
+import org.jetbrains.exposed.sql.vendors.MysqlDialect
+import org.jetbrains.exposed.sql.vendors.OracleDialect
+import org.jetbrains.exposed.sql.vendors.SQLServerDialect
+import org.jetbrains.exposed.sql.vendors.h2Mode
 import org.junit.Test
 import kotlin.test.assertNotNull
 import kotlin.test.assertNull
@@ -570,25 +575,27 @@ class FunctionsTests : DatabaseTestsBase() {
  @Test
  fun testCoalesceFunction() {
  withCitiesAndUsers { _, users, _ ->
- val coalesceExp1 = Coalesce(users.cityId, intLiteral(1000))
+ val coalesceExp1 = coalesce(users.cityId, intLiteral(1000))
 
  users.select(users.cityId, coalesceExp1).forEach {
  val cityId = it[users.cityId]
+ val actual: Int = it[coalesceExp1]
  if (cityId != null) {
- assertEquals(cityId, it[coalesceExp1])
+ assertEquals(cityId, actual)
  } else {
- assertEquals(1000, it[coalesceExp1])
+ assertEquals(1000, actual)
  }
  }
 
  val coalesceExp2 = Coalesce(users.cityId, Op.nullOp<Int>(), intLiteral(1000))
 
  users.select(users.cityId, coalesceExp2).forEach {
  val cityId = it[users.cityId]
+ val actual: Int = it[coalesceExp2]
  if (cityId != null) {
- assertEquals(cityId, it[coalesceExp2])
+ assertEquals(cityId, actual)
  } else {
- assertEquals(1000, it[coalesceExp2])
+ assertEquals(1000, actual)
  }
  }
  }