fix: EXPOSED-178 DELETE_RULE read incorrectly for Oracle

Oracle returns CASCADE=0, SET_NULL=2, and NO_ACTION=1
`decode (f.delete_rule, 'CASCADE', 0, 'SET NULL', 2, 1) as delete_rule`

So when it returns 1, which in the current code corresponds to DatabaseMetaData.importedKeyRestrict, it will now be mapped to NO_ACTION because Oracle does not have the RESTRICT reference option. NO_ACTION behaves likes RESTRICT for it.

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

@@ -7,7 +7,6 @@ import org.jetbrains.exposed.sql.vendors.SQLiteDialect
 import org.jetbrains.exposed.sql.vendors.currentDialect
 import org.jetbrains.exposed.sql.vendors.currentDialectIfAvailable
 import org.jetbrains.exposed.sql.vendors.inProperCase
-import java.sql.DatabaseMetaData
 
 /**
  * Common interface for database objects that can be created, modified and dropped.
@@ -36,18 +35,6 @@ enum class ReferenceOption {
     SET_DEFAULT;
 
     override fun toString(): String = name.replace("_", " ")
-
-    companion object {
-        /** Returns the corresponding [ReferenceOption] for the specified [refOption] from JDBC. */
-        fun resolveRefOptionFromJdbc(refOption: Int): ReferenceOption = when (refOption) {
-            DatabaseMetaData.importedKeyCascade -> CASCADE
-            DatabaseMetaData.importedKeySetNull -> SET_NULL
-            DatabaseMetaData.importedKeyRestrict -> RESTRICT
-            DatabaseMetaData.importedKeyNoAction -> NO_ACTION
-            DatabaseMetaData.importedKeySetDefault -> SET_DEFAULT
-            else -> currentDialect.defaultReferenceOption
-        }
-    }
 }
 
 /**

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

@@ -2,6 +2,7 @@ package org.jetbrains.exposed.sql.vendors
 
 import org.jetbrains.exposed.sql.*
 import org.jetbrains.exposed.sql.transactions.TransactionManager
+import java.sql.DatabaseMetaData
 
 /**
  * Common interface for all database dialects.
@@ -145,6 +146,16 @@ interface DatabaseDialect {
         }
     }
 
+    /** Returns the corresponding [ReferenceOption] for the specified [refOption] from JDBC. */
+    fun resolveRefOptionFromJdbc(refOption: Int): ReferenceOption = when (refOption) {
+        DatabaseMetaData.importedKeyCascade -> ReferenceOption.CASCADE
+        DatabaseMetaData.importedKeySetNull -> ReferenceOption.SET_NULL
+        DatabaseMetaData.importedKeyRestrict -> ReferenceOption.RESTRICT
+        DatabaseMetaData.importedKeyNoAction -> ReferenceOption.NO_ACTION
+        DatabaseMetaData.importedKeySetDefault -> ReferenceOption.SET_DEFAULT
+        else -> currentDialect.defaultReferenceOption
+    }
+
     companion object {
         private val defaultLikePatternSpecialChars = mapOf('%' to null, '_' to null)
     }

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

@@ -3,6 +3,7 @@ package org.jetbrains.exposed.sql.vendors
 import org.jetbrains.exposed.exceptions.throwUnsupportedException
 import org.jetbrains.exposed.sql.*
 import org.jetbrains.exposed.sql.transactions.TransactionManager
+import java.sql.DatabaseMetaData
 import java.util.*
 
 internal object OracleDataTypeProvider : DataTypeProvider() {
@@ -366,5 +367,16 @@ open class OracleDialect : VendorDialect(dialectName, OracleDataTypeProvider, Or
         }
     }
 
+    /**
+     * The SQL that gets the constraint information for Oracle returns a 1 for NO ACTION and does not support RESTRICT.
+     * `decode (f.delete_rule, 'CASCADE', 0, 'SET NULL', 2, 1) as delete_rule`
+     */
+    override fun resolveRefOptionFromJdbc(refOption: Int): ReferenceOption = when (refOption) {
+        DatabaseMetaData.importedKeyCascade -> ReferenceOption.CASCADE
+        DatabaseMetaData.importedKeySetNull -> ReferenceOption.SET_NULL
+        DatabaseMetaData.importedKeyRestrict -> ReferenceOption.NO_ACTION
+        else -> currentDialect.defaultReferenceOption
+    }
+
     companion object : DialectNameProvider("Oracle")
 }

exposed-jdbc/src/main/kotlin/org/jetbrains/exposed/sql/statements/jdbc/JdbcDatabaseMetadataImpl.kt

@@ -288,9 +288,9 @@ class JdbcDatabaseMetadataImpl(database: String, val metadata: DatabaseMetaData)
                     identifierManager.quoteIdentifierWhenWrongCaseOrNecessary(it.nameInDatabaseCase()) == targetColumnName
                 } ?: return@iterate null // Do not crash if there are missing fields in Exposed's tables
                 val constraintUpdateRule = getObject("UPDATE_RULE")?.toString()?.toIntOrNull()?.let {
-                    ReferenceOption.resolveRefOptionFromJdbc(it)
+                    currentDialect.resolveRefOptionFromJdbc(it)
                 }
-                val constraintDeleteRule = ReferenceOption.resolveRefOptionFromJdbc(getInt("DELETE_RULE"))
+                val constraintDeleteRule = currentDialect.resolveRefOptionFromJdbc(getInt("DELETE_RULE"))
                 ForeignKeyConstraint(
                     target = targetColumn,
                     from = fromColumn,

exposed-tests/src/test/kotlin/org/jetbrains/exposed/sql/tests/sqlite/ForeignKeyConstraintTests.kt

@@ -171,7 +171,7 @@ class ForeignKeyConstraintTests : DatabaseTestsBase() {
     }
 
     @Test
-    fun testUpdateRuleReadCorrectlyWhenNotSpecifiedInChildTable() {
+    fun testUpdateAndDeleteRulesReadCorrectlyWhenNotSpecifiedInChildTable() {
         val category = object : Table("Category") {
             val id = integer("id")
 
@@ -193,9 +193,14 @@ class ForeignKeyConstraintTests : DatabaseTestsBase() {
                 constraints.values.forEach { list ->
                     list.forEach {
                         when (testDb) {
-                            TestDB.H2_ORACLE, TestDB.H2_SQLSERVER ->
+                            TestDB.H2_ORACLE, TestDB.H2_SQLSERVER -> {
                                 assertEquals(ReferenceOption.RESTRICT, it.updateRule)
-                            else -> assertEquals(currentDialectTest.defaultReferenceOption, it.updateRule)
+                                assertEquals(ReferenceOption.RESTRICT, it.deleteRule)
+                            }
+                            else -> {
+                                assertEquals(currentDialectTest.defaultReferenceOption, it.updateRule)
+                                assertEquals(currentDialectTest.defaultReferenceOption, it.deleteRule)
+                            }
                         }
                     }
                 }
@@ -204,7 +209,7 @@ class ForeignKeyConstraintTests : DatabaseTestsBase() {
     }
 
     @Test
-    fun testUpdateRuleReadCorrectlyWhenSpecifiedInChildTable() {
+    fun testUpdateAndDeleteRulesReadCorrectlyWhenSpecifiedInChildTable() {
         val category = object : Table("Category") {
             val id = integer("id")
 
@@ -213,7 +218,12 @@ class ForeignKeyConstraintTests : DatabaseTestsBase() {
 
         val item = object : Table("Item") {
             val id = integer("id")
-            val categoryId = integer("categoryId").references(category.id, onUpdate = ReferenceOption.CASCADE)
+            val categoryId = integer("categoryId")
+                .references(
+                    category.id,
+                    onUpdate = ReferenceOption.CASCADE,
+                    onDelete = ReferenceOption.CASCADE
+                )
 
             override val primaryKey = PrimaryKey(id)
         }
@@ -226,6 +236,7 @@ class ForeignKeyConstraintTests : DatabaseTestsBase() {
                 constraints.values.forEach { list ->
                     list.forEach {
                         assertEquals(ReferenceOption.CASCADE, it.updateRule)
+                        assertEquals(ReferenceOption.CASCADE, it.deleteRule)
                     }
                 }
             }