feat(NODE-4924)!: remove mapReduce collection helper (#3511)

Author: baileympearson

etc/notes/CHANGES_5.0.0.md

@@ -16,6 +16,43 @@ The following is a detailed collection of the changes in the major v5 release of
 
 ## Changes
 
+### `Collection.mapReduce()` helper removed
+
+The `mapReduce` helper has been removed from the `Collection` class.  The `mapReduce` operation has been
+deprecated in favor of the aggregation pipeline since MongoDB server version 5.0.  It is recommended
+to migrate code that uses `Collection.mapReduce` to use the aggregation pipeline (see [Map-Reduce to Aggregation Pipeline](https://www.mongodb.com/docs/manual/reference/map-reduce-to-aggregation-pipeline/)).
+
+If the `mapReduce` command must be used, the `Db.command()` helper can be used to run the raw
+`mapReduce` command.
+
+```typescript
+// using the Collection.mapReduce helper in <4.x drivers
+const collection = db.collection('my-collection');
+
+await collection.mapReduce(
+  function() { emit(this.user_id, 1); },
+  function(k, vals) { return 1 },
+  {
+    out: 'inline',
+    readConcern: 'majority'
+  }
+)
+
+// manually running the command using `db.command()`
+const command = {
+  mapReduce: 'my-collection',
+  map: 'function() { emit(this.user_id, 1); }',
+  reduce: 'function(k,vals) { return 1; }',
+  out: 'inline',
+  readConcern: 'majority'
+}
+
+await db.command(command);
+```
+
+**Note** When using the `Db.command()` helper, all `mapReduce` options should be specified
+on the raw command object and should not be passed through the options object.
+
 ### `AddUserOptions.digestPassword` removed
 
 The `digestPassword` option has been removed from the add user helper.

src/collection.ts

@@ -68,12 +68,6 @@ import {
   InsertOneResult
 } from './operations/insert';
 import { IsCappedOperation } from './operations/is_capped';
-import {
-  MapFunction,
-  MapReduceOperation,
-  MapReduceOptions,
-  ReduceFunction
-} from './operations/map_reduce';
 import type { Hint, OperationOptions } from './operations/operation';
 import { OptionsOperation } from './operations/options_operation';
 import { RenameOperation, RenameOptions } from './operations/rename';
@@ -1524,79 +1518,6 @@ export class Collection<TSchema extends Document = Document> {
     return new ChangeStream<TLocal, TChange>(this, pipeline, resolveOptions(this, options));
   }
 
-  /**
-   * Run Map Reduce across a collection. Be aware that the inline option for out will return an array of results not a collection.
-   *
-   * @deprecated collection.mapReduce is deprecated. Use the aggregation pipeline instead. Visit https://docs.mongodb.com/manual/reference/map-reduce-to-aggregation-pipeline for more information on how to translate map-reduce operations to the aggregation pipeline.
-   * @param map - The mapping function.
-   * @param reduce - The reduce function.
-   * @param options - Optional settings for the command
-   * @param callback - An optional callback, a Promise will be returned if none is provided
-   */
-  mapReduce<TKey = any, TValue = any>(
-    map: string | MapFunction<TSchema>,
-    reduce: string | ReduceFunction<TKey, TValue>
-  ): Promise<Document | Document[]>;
-  mapReduce<TKey = any, TValue = any>(
-    map: string | MapFunction<TSchema>,
-    reduce: string | ReduceFunction<TKey, TValue>,
-    options: MapReduceOptions<TKey, TValue>
-  ): Promise<Document | Document[]>;
-  /** @deprecated Callbacks are deprecated and will be removed in the next major version. See [mongodb-legacy](https://github.com/mongodb-js/nodejs-mongodb-legacy) for migration assistance */
-  mapReduce<TKey = any, TValue = any>(
-    map: string | MapFunction<TSchema>,
-    reduce: string | ReduceFunction<TKey, TValue>,
-    callback: Callback<Document | Document[]>
-  ): void;
-  /** @deprecated Callbacks are deprecated and will be removed in the next major version. See [mongodb-legacy](https://github.com/mongodb-js/nodejs-mongodb-legacy) for migration assistance */
-  mapReduce<TKey = any, TValue = any>(
-    map: string | MapFunction<TSchema>,
-    reduce: string | ReduceFunction<TKey, TValue>,
-    options: MapReduceOptions<TKey, TValue>,
-    callback: Callback<Document | Document[]>
-  ): void;
-  mapReduce<TKey = any, TValue = any>(
-    map: string | MapFunction<TSchema>,
-    reduce: string | ReduceFunction<TKey, TValue>,
-    options?: MapReduceOptions<TKey, TValue> | Callback<Document | Document[]>,
-    callback?: Callback<Document | Document[]>
-  ): Promise<Document | Document[]> | void {
-    emitWarningOnce(
-      'collection.mapReduce is deprecated. Use the aggregation pipeline instead. Visit https://docs.mongodb.com/manual/reference/map-reduce-to-aggregation-pipeline for more information on how to translate map-reduce operations to the aggregation pipeline.'
-    );
-    if ('function' === typeof options) (callback = options), (options = {});
-    // Out must always be defined (make sure we don't break weirdly on pre 1.8+ servers)
-    // TODO NODE-3339: Figure out if this is still necessary given we no longer officially support pre-1.8
-    if (options?.out == null) {
-      throw new MongoInvalidArgumentError(
-        'Option "out" must be defined, see mongodb docs for possible values'
-      );
-    }
-
-    if ('function' === typeof map) {
-      map = map.toString();
-    }
-
-    if ('function' === typeof reduce) {
-      reduce = reduce.toString();
-    }
-
-    if ('function' === typeof options.finalize) {
-      options.finalize = options.finalize.toString();
-    }
-
-    return executeOperation(
-      this.s.db.s.client,
-      new MapReduceOperation(
-        this as TODO_NODE_3286,
-        map,
-        reduce,
-        resolveOptions(this, options) as TODO_NODE_3286
-      ),
-      callback
-    );
-  }
-
   /**
    * Initiate an Out of order batch write operation. All operations will be buffered into insert/update/remove commands executed out of order.
    *

src/index.ts

@@ -385,12 +385,6 @@ export type {
 export type { InsertManyResult, InsertOneOptions, InsertOneResult } from './operations/insert';
 export type { CollectionInfo, ListCollectionsOptions } from './operations/list_collections';
 export type { ListDatabasesOptions, ListDatabasesResult } from './operations/list_databases';
-export type {
-  FinalizeFunction,
-  MapFunction,
-  MapReduceOptions,
-  ReduceFunction
-} from './operations/map_reduce';
 export type { AbstractOperation, Hint, OperationOptions } from './operations/operation';
 export type { ProfilingLevelOptions } from './operations/profiling_level';
 export type { RemoveUserOptions } from './operations/remove_user';