From 2ab93f0bee14450eaaa40295f4a7a68d38db590c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ivan=20=E2=80=9CCLOVIS=E2=80=9D=20Canet?=
 <ivan.canet@gmail.com>
Date: Sat, 12 Sep 2026 20:08:30 +0200
Subject: [PATCH] feat(driver-coroutines): Implement
 MongoCollection.unsafeCast()

---
 .../CoroutineFilteredMongoCollectionImpl.kt   |  4 ++
 .../kotlin/CoroutineMongoCollection.kt        | 55 +++++++++++++++++++
 .../kotlin/CoroutineMongoCollectionImpl.kt    |  5 ++
 .../MultiplatformMongoCollectionImpl.kt       |  3 +
 4 files changed, 67 insertions(+)

diff --git a/driver-coroutines/src/jvmMain/kotlin/CoroutineFilteredMongoCollectionImpl.kt b/driver-coroutines/src/jvmMain/kotlin/CoroutineFilteredMongoCollectionImpl.kt
index 1c2e4843..3043a9a6 100644
--- a/driver-coroutines/src/jvmMain/kotlin/CoroutineFilteredMongoCollectionImpl.kt
+++ b/driver-coroutines/src/jvmMain/kotlin/CoroutineFilteredMongoCollectionImpl.kt
@@ -91,6 +91,10 @@ private class CoroutineFilteredMongoCollectionImpl<Document : Any>(
 	override val context: BsonContext
 		get() = upstream.context
 
+	@Suppress("UNCHECKED_CAST")
+	override fun <NewType : Any> unsafeCast(type: KType): CoroutineMongoCollection<NewType> =
+		CoroutineFilteredMongoCollectionImpl(upstream.unsafeCast(type), globalFilter as FilterQuery<NewType>.() -> Unit)
+
 	override suspend fun create(options: CreateCollectionOptions<Document>.() -> Unit) {
 		error("It is not possible to call 'create' on the filtered collection $this:\nA filtered collection is a driver-side view, it cannot exist in the database itself.")
 	}
diff --git a/driver-coroutines/src/jvmMain/kotlin/CoroutineMongoCollection.kt b/driver-coroutines/src/jvmMain/kotlin/CoroutineMongoCollection.kt
index 8057bd2c..809ab674 100644
--- a/driver-coroutines/src/jvmMain/kotlin/CoroutineMongoCollection.kt
+++ b/driver-coroutines/src/jvmMain/kotlin/CoroutineMongoCollection.kt
@@ -28,6 +28,8 @@ import opensavvy.ktmongo.dsl.command.UpdateOptions
 import opensavvy.ktmongo.dsl.query.FilterQuery
 import opensavvy.ktmongo.dsl.query.UpdateWithPipelineQuery
 import opensavvy.ktmongo.dsl.query.UpsertQuery
+import kotlin.reflect.KType
+import kotlin.reflect.typeOf
 
 /**
  * A collection stores related documents together.
@@ -95,4 +97,57 @@ interface CoroutineMongoCollection<Document : Any> : MongoCollection<Document> {
 	override fun aggregate(): CoroutineMongoAggregationPipeline<Document>
 
 	override fun filter(filter: FilterQuery<Document>.() -> Unit): CoroutineMongoCollection<Document>
+
+	/**
+	 * Overwrites the represented type of this value.
+	 *
+	 * This method can be useful to bypass type checks.
+	 *
+	 * ### Example
+	 *
+	 * If we know there are some documents that have the wrong format, we can use `unsafeCast` to find them
+	 * without needing to add their fields to the production DTO.
+	 *
+	 * ```kotlin
+	 * class User(
+	 *     val _id: ObjectId,
+	 *     val name: String,
+	 * )
+	 *
+	 * users.unsafeCast<BsonDocument>() // Treat all data as arbitrary BSON documents
+	 *     .find { BsonDocument.get<String?>("oldField") ne null }
+	 *     .forEach {
+	 *         println(it["oldField"]?.decodeString())
+	 *     }
+	 * ```
+	 */
+	override fun <NewType : Any> unsafeCast(type: KType): CoroutineMongoCollection<NewType>
+
+	/**
+	 * Overwrites the represented type of this value.
+	 *
+	 * This method can be useful to bypass type checks.
+	 *
+	 * ### Example
+	 *
+	 * If we know there are some documents that have the wrong format, we can use `unsafeCast` to find them
+	 * without needing to add their fields to the production DTO.
+	 *
+	 * ```kotlin
+	 * class User(
+	 *     val _id: ObjectId,
+	 *     val name: String,
+	 * )
+	 *
+	 * users.unsafeCast<BsonDocument>() // Treat all data as arbitrary BSON documents
+	 *     .find { BsonDocument.get<String?>("oldField") ne null }
+	 *     .forEach {
+	 *         println(it["oldField"]?.decodeString())
+	 *     }
+	 * ```
+	 */
+	@Suppress("WRONG_MODIFIER_CONTAINING_DECLARATION")
+	final inline fun <reified T : Any> unsafeCast(): CoroutineMongoCollection<T> =
+		unsafeCast(typeOf<T>())
+
 }
diff --git a/driver-coroutines/src/jvmMain/kotlin/CoroutineMongoCollectionImpl.kt b/driver-coroutines/src/jvmMain/kotlin/CoroutineMongoCollectionImpl.kt
index 384991ff..88472526 100644
--- a/driver-coroutines/src/jvmMain/kotlin/CoroutineMongoCollectionImpl.kt
+++ b/driver-coroutines/src/jvmMain/kotlin/CoroutineMongoCollectionImpl.kt
@@ -47,6 +47,7 @@ import opensavvy.ktmongo.official.options.toJava
 import opensavvy.ktmongo.official.toJava
 import opensavvy.ktmongo.official.toKtMongo
 import java.util.concurrent.TimeUnit
+import kotlin.reflect.KClass
 import kotlin.reflect.KType
 import kotlin.reflect.typeOf
 import com.mongodb.client.model.ReplaceOptions as MongoReplaceOptions
@@ -82,6 +83,10 @@ private class CoroutineMongoCollectionImpl<Document : Any>(
 	@LowLevelApi
 	override val context: BsonContext = CoroutineBsonContext()
 
+	@Suppress("UNCHECKED_CAST")
+	override fun <NewType : Any> unsafeCast(type: KType): CoroutineMongoCollection<NewType> =
+		CoroutineMongoCollectionImpl(inner.withDocumentClass((type.classifier as KClass<NewType>).java), factory, propertyNameStrategy, objectIdGenerator, type, innerDatabase)
+
 	// region Count
 
 	override suspend fun count(): Long =
diff --git a/driver-multiplatform/src/commonMain/kotlin/MultiplatformMongoCollectionImpl.kt b/driver-multiplatform/src/commonMain/kotlin/MultiplatformMongoCollectionImpl.kt
index 16788d63..0625aa29 100644
--- a/driver-multiplatform/src/commonMain/kotlin/MultiplatformMongoCollectionImpl.kt
+++ b/driver-multiplatform/src/commonMain/kotlin/MultiplatformMongoCollectionImpl.kt
@@ -59,6 +59,9 @@ internal class MultiplatformMongoCollectionImpl<Document : Any>(
 		nameStrategy = propertyNameStrategy,
 	)
 
+	override fun <NewType : Any> unsafeCast(type: KType): MultiplatformMongoCollection<NewType> =
+		MultiplatformMongoCollectionImpl(database, name, type, factory, propertyNameStrategy, objectIdGenerator)
+
 	override suspend fun insertOne(
 		document: Document,
 		options: InsertOneOptions<Document>.() -> Unit,
-- 
2.51.2