From fbbb22731279cd77c458de38715d637cc05b45f4 Mon Sep 17 00:00:00 2001
From: Maxime Girardet <maximeinformatique@free.fr>
Date: Mon, 26 May 2025 21:19:05 +0000
Subject: [PATCH] merge: Implement the $mul update operator

See merge request opensavvy/ktmongo!74
---
 dsl/src/commonMain/kotlin/query/UpdateQuery.kt | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 dsl/src/commonMain/kotlin/query/UpdateQueryImpl.kt | 30 ++++++++++++++++++++++++++++++
 dsl/src/commonTest/kotlin/query/update/FieldUpdateTest.kt | 40 ++++++++++++++++++++++++++++++++++++++++
 dsl/src/commonTest/kotlin/query/update/UpdateUtils.kt | 1 +
 4 file(s) changed, 134 insertion(s)(+), 0 deletion(s)(-)

diff --git a/dsl/src/commonMain/kotlin/query/UpdateQuery.kt b/dsl/src/commonMain/kotlin/query/UpdateQuery.kt
--- a/dsl/src/commonMain/kotlin/query/UpdateQuery.kt
+++ b/dsl/src/commonMain/kotlin/query/UpdateQuery.kt
@@ -394,6 +394,69 @@
 		this.field.plusAssign(amount)
 
 	// endregion
+	// region $mul
+
+	/**
+	 * Multiplies a field by the specified [amount].
+	 *
+	 * If the field doesn't exist (either the document doesn't have it, or the operation is an upsert and a new document is created),
+	 * the field is created with an initial value of 0.
+	 *
+	 * Use of this operator with a field with a `null` value will generate an error.
+	 *
+	 * ### Example
+	 *
+	 * ```kotlin
+	 * class User(
+	 *     val name: String,
+	 *     val price: Double,
+	 * )
+	 *
+	 * collection.updateMany {
+	 *     User::price mul 2.0
+	 * }
+	 * ```
+	 *
+	 * ### External resources
+	 *
+	 * - [Official documentation](https://www.mongodb.com/docs/manual/reference/operator/update/mul/)
+	 */
+	@Suppress("INVISIBLE_REFERENCE")
+	@KtMongoDsl
+	infix fun <@kotlin.internal.OnlyInputTypes V : Number> Field<T, V>.mul(amount: V)
+
+	/**
+	 * Multiplies a field by the specified [amount].
+	 *
+	 * If the field doesn't exist (either the document doesn't have it, or the operation is an upsert and a new document is created),
+	 * the field is created with an initial value of 0.
+	 *
+	 * Use of this operator with a field with a `null` value will generate an error.
+	 *
+	 * ### Example
+	 *
+	 * ```kotlin
+	 * class User(
+	 *     val name: String,
+	 *     val price: Double,
+	 * )
+	 *
+	 * collection.updateMany {
+	 *     User::price mul 2.0
+	 * }
+	 * ```
+	 *
+	 * ### External resources
+	 *
+	 * - [Official documentation](https://www.mongodb.com/docs/manual/reference/operator/update/mul/)
+	 */
+	@Suppress("INVISIBLE_REFERENCE")
+	@KtMongoDsl
+	infix fun <@kotlin.internal.OnlyInputTypes V : Number> KProperty1<T, V>.mul(amount: V) {
+		this.field.mul(amount)
+	}
+
+	// endregion
 	// region $unset
 
 	/**
diff --git a/dsl/src/commonMain/kotlin/query/UpdateQueryImpl.kt b/dsl/src/commonMain/kotlin/query/UpdateQueryImpl.kt
--- a/dsl/src/commonMain/kotlin/query/UpdateQueryImpl.kt
+++ b/dsl/src/commonMain/kotlin/query/UpdateQueryImpl.kt
@@ -167,6 +167,33 @@
 	}
 
 	// endregion
+	// region $mul
+
+	@OptIn(LowLevelApi::class, DangerousMongoApi::class)
+	@Suppress("INVISIBLE_REFERENCE")
+	@KtMongoDsl
+	override infix fun <@kotlin.internal.OnlyInputTypes V : Number> Field<T, V>.mul(amount: V) {
+		accept(MultiplyBsonNodeNode(listOf(this.path to amount), context))
+	}
+
+	@LowLevelApi
+	private class MultiplyBsonNodeNode(
+		val mappings: List<Pair<Path, Number>>,
+		context: BsonContext,
+	) : UpdateBsonNodeNode(context) {
+		override fun simplify(): AbstractBsonNode? =
+			this.takeUnless { mappings.isEmpty() }
+
+		override fun write(writer: BsonFieldWriter) = with(writer) {
+			writeDocument("\$mul") {
+				for ((field, value) in mappings) {
+					writeObjectSafe(field.toString(), value)
+				}
+			}
+		}
+	}
+
+	// endregion
 	// region $unset
 
 	@OptIn(LowLevelApi::class, DangerousMongoApi::class)
@@ -233,6 +260,9 @@
 			},
 			OperatorCombinator(IncrementBsonNodeNode::class) { sources, context ->
 				IncrementBsonNodeNode(sources.flatMap { it.mappings }, context)
+			},
+			OperatorCombinator(MultiplyBsonNodeNode::class) { sources, context ->
+				MultiplyBsonNodeNode(sources.flatMap { it.mappings }, context)
 			},
 			OperatorCombinator(UnsetBsonNodeNode::class) { sources, context ->
 				UnsetBsonNodeNode(sources.flatMap { it.fields }, context)
diff --git a/dsl/src/commonTest/kotlin/query/update/FieldUpdateTest.kt b/dsl/src/commonTest/kotlin/query/update/FieldUpdateTest.kt
--- a/dsl/src/commonTest/kotlin/query/update/FieldUpdateTest.kt
+++ b/dsl/src/commonTest/kotlin/query/update/FieldUpdateTest.kt
@@ -140,6 +140,46 @@
 		}
 	}
 
+	suite("Operator $mul") {
+		test("Single field") {
+			update {
+				User::money mul 18.0
+			} shouldBeBson """
+				{
+					"$mul": {
+						"money": 18.0
+					}
+				}
+			""".trimIndent()
+		}
+
+		test("Nested field") {
+			update {
+				User::bestFriend / Friend::money mul -12.9f
+			} shouldBeBson """
+				{
+					"$mul": {
+						"bestFriend.money": -12.899999618530273
+					}
+				}
+			""".trimIndent()
+		}
+
+		test("Multiple fields") {
+			update {
+				User::money mul 5.2
+				User::bestFriend / Friend::money mul -5.2f
+			} shouldBeBson """
+				{
+					"$mul": {
+						"money": 5.2,
+						"bestFriend.money": -5.199999809265137
+					}
+				}
+			""".trimIndent()
+		}
+	}
+
 	suite("Operator $unset") {
 		test("Single field") {
 			update {
diff --git a/dsl/src/commonTest/kotlin/query/update/UpdateUtils.kt b/dsl/src/commonTest/kotlin/query/update/UpdateUtils.kt
--- a/dsl/src/commonTest/kotlin/query/update/UpdateUtils.kt
+++ b/dsl/src/commonTest/kotlin/query/update/UpdateUtils.kt
@@ -28,6 +28,7 @@
 val set = "\$set"
 val setOnInsert = "\$setOnInsert"
 val inc = "\$inc"
+val mul = "\$mul"
 val unset = "\$unset"
 val rename = "\$rename"
 

--
tangled.sh