fix(NODE-5981): read preference not applied to commands properly

src/cmap/commands.ts

@@ -1,7 +1,7 @@
 import type { BSONSerializeOptions, Document, Long } from '../bson';
 import * as BSON from '../bson';
 import { MongoInvalidArgumentError, MongoRuntimeError } from '../error';
-import { ReadPreference } from '../read_preference';
+import { type ReadPreference } from '../read_preference';
 import type { ClientSession } from '../sessions';
 import type { CommandOptions } from './connection';
 import {
@@ -51,7 +51,6 @@ export interface OpQueryOptions extends CommandOptions {
   requestId?: number;
   moreToCome?: boolean;
   exhaustAllowed?: boolean;
-  readPreference?: ReadPreference;
 }
 
 /**************************************************************
@@ -77,7 +76,6 @@ export class OpQueryRequest {
   awaitData: boolean;
   exhaust: boolean;
   partial: boolean;
-  documentsReturnedIn?: string;
 
   constructor(public databaseName: string, public query: Document, options: OpQueryOptions) {
     // Basic options needed to be passed in
@@ -503,10 +501,6 @@ export class OpMsgRequest {
     // Basic options
     this.command.$db = databaseName;
 
-    if (options.readPreference && options.readPreference.mode !== ReadPreference.PRIMARY) {
-      this.command.$readPreference = options.readPreference.toJSON();
-    }
-
     // Ensure empty options
     this.options = options ?? {};
 

src/cmap/connection.ts

@@ -26,7 +26,8 @@ import type { ServerApi, SupportedNodeConnectionOptions } from '../mongo_client'
 import { type MongoClientAuthProviders } from '../mongo_client_auth_providers';
 import { MongoLoggableComponent, type MongoLogger, SeverityLevel } from '../mongo_logger';
 import { type CancellationToken, TypedEventEmitter } from '../mongo_types';
-import type { ReadPreferenceLike } from '../read_preference';
+import { ReadPreference, type ReadPreferenceLike } from '../read_preference';
+import { ServerType } from '../sdam/common';
 import { applySession, type ClientSession, updateSessionFromResponse } from '../sessions';
 import {
   BufferPool,
@@ -83,6 +84,8 @@ export interface CommandOptions extends BSONSerializeOptions {
   willRetryWrite?: boolean;
 
   writeConcern?: WriteConcern;
+
+  directConnection?: boolean;
 }
 
 /** @public */
@@ -371,16 +374,34 @@ export class Connection extends TypedEventEmitter<ConnectionEvents> {
       cmd.$clusterTime = clusterTime;
     }
 
-    if (
-      isSharded(this) &&
-      !this.supportsOpMsg &&
-      readPreference &&
-      readPreference.mode !== 'primary'
-    ) {
-      cmd = {
-        $query: cmd,
-        $readPreference: readPreference.toJSON()
-      };
+    // For standalone, drivers MUST NOT set $readPreference.
+    if (this.description.type !== ServerType.Standalone) {
+      if (
+        !isSharded(this) &&
+        !this.description.loadBalanced &&
+        this.supportsOpMsg &&
+        options.directConnection === true &&
+        readPreference?.mode === 'primary'
+      ) {
+        // For mongos and load balancers with 'primary' mode, drivers MUST NOT set $readPreference.
+        // For all other types with a direct connection, if the read preference is 'primary'
+        // (driver sets 'primary' as default if no read preference is configured),
+        // the $readPreference MUST be set to 'primaryPreferred'
+        // to ensure that any server type can handle the request.
+        cmd.$readPreference = ReadPreference.primaryPreferred.toJSON();
+      } else if (isSharded(this) && !this.supportsOpMsg && readPreference?.mode !== 'primary') {
+        // When sending a read operation via OP_QUERY and the $readPreference modifier,
+        // the query MUST be provided using the $query modifier.
+        cmd = {
+          $query: cmd,
+          $readPreference: readPreference.toJSON()
+        };
+      } else if (readPreference?.mode !== 'primary') {
+        // For mode 'primary', drivers MUST NOT set $readPreference.
+        // For all other read preference modes (i.e. 'secondary', 'primaryPreferred', ...),
+        // drivers MUST set $readPreference
+        cmd.$readPreference = readPreference.toJSON();
+      }
     }
 
     const commandOptions = {
@@ -389,8 +410,7 @@ export class Connection extends TypedEventEmitter<ConnectionEvents> {
       checkKeys: false,
       // This value is not overridable
       secondaryOk: readPreference.secondaryOk(),
-      ...options,
-      readPreference // ensure we pass in ReadPreference instance
+      ...options
     };
 
     const message = this.supportsOpMsg

src/cmap/stream_description.ts

@@ -22,7 +22,7 @@ export interface StreamDescriptionOptions {
 /** @public */
 export class StreamDescription {
   address: string;
-  type: string;
+  type: ServerType;
   minWireVersion?: number;
   maxWireVersion?: number;
   maxBsonObjectSize: number;

src/cmap/wire_protocol/shared.ts

@@ -13,12 +13,8 @@ export interface ReadPreferenceOption {
 }
 
 export function getReadPreference(options?: ReadPreferenceOption): ReadPreference {
-  // Default to command version of the readPreference
+  // Default to command version of the readPreference.
   let readPreference = options?.readPreference ?? ReadPreference.primary;
-  // If we have an option readPreference override the command one
-  if (options?.readPreference) {
-    readPreference = options.readPreference;
-  }
 
   if (typeof readPreference === 'string') {
     readPreference = ReadPreference.fromString(readPreference);
@@ -43,7 +39,7 @@ export function isSharded(topologyOrServer?: Topology | Server | Connection): bo
   }
 
   // NOTE: This is incredibly inefficient, and should be removed once command construction
-  //       happens based on `Server` not `Topology`.
+  // happens based on `Server` not `Topology`.
   if (topologyOrServer.description && topologyOrServer.description instanceof TopologyDescription) {
     const servers: ServerDescription[] = Array.from(topologyOrServer.description.servers.values());
     return servers.some((server: ServerDescription) => server.type === ServerType.Mongos);

src/mongo_client.ts

@@ -821,6 +821,7 @@ export interface MongoOptions
   readPreference: ReadPreference;
   readConcern: ReadConcern;
   loadBalanced: boolean;
+  directConnection: boolean;
   serverApi: ServerApi;
   compressors: CompressorName[];
   writeConcern: WriteConcern;

src/sdam/server.ts

@@ -290,7 +290,10 @@ export class Server extends TypedEventEmitter<ServerEvents> {
     }
 
     // Clone the options
-    const finalOptions = Object.assign({}, options, { wireProtocolCommand: false });
+    const finalOptions = Object.assign({}, options, {
+      wireProtocolCommand: false,
+      directConnection: this.topology.s.options.directConnection
+    });
 
     // There are cases where we need to flag the read preference not to get sent in
     // the command, such as pre-5.0 servers attempting to perform an aggregate write

test/integration/max-staleness/max_staleness.test.js

@@ -18,7 +18,7 @@ describe('Max Staleness', function () {
       // Primary server states
       const serverIsPrimary = [Object.assign({}, defaultFields)];
       server.setMessageHandler(request => {
-        var doc = request.document;
+        const doc = request.document;
         if (isHello(doc)) {
           request.reply(serverIsPrimary[0]);
           return;
@@ -46,71 +46,53 @@ describe('Max Staleness', function () {
     metadata: {
       requires: {
         generators: true,
-        topology: 'single'
+        topology: 'replicaset'
       }
     },
 
-    test: function (done) {
-      var self = this;
+    test: async function () {
+      const self = this;
       const configuration = this.configuration;
       const client = configuration.newClient(
         `mongodb://${test.server.uri()}/test?readPreference=secondary&maxStalenessSeconds=250`,
         { serverApi: null } // TODO(NODE-3807): remove resetting serverApi when the usage of mongodb mock server is removed
       );
 
-      client.connect(function (err, client) {
-        expect(err).to.not.exist;
-        var db = client.db(self.configuration.db);
-
-        db.collection('test')
-          .find({})
-          .toArray(function (err) {
-            expect(err).to.not.exist;
-            expect(test.checkCommand).to.containSubset({
-              $query: { find: 'test', filter: {} },
-              $readPreference: { mode: 'secondary', maxStalenessSeconds: 250 }
-            });
-
-            client.close(done);
-          });
+      await client.connect();
+      const db = client.db(self.configuration.db);
+      await db.collection('test').find({}).toArray();
+      expect(test.checkCommand).to.containSubset({
+        $readPreference: { mode: 'secondary', maxStalenessSeconds: 250 }
       });
+      await client.close();
     }
   });
 
   it('should correctly set maxStalenessSeconds on Mongos query using db level readPreference', {
     metadata: {
       requires: {
         generators: true,
-        topology: 'single'
+        topology: 'replicaset'
       }
     },
 
-    test: function (done) {
+    test: async function () {
       const configuration = this.configuration;
       const client = configuration.newClient(`mongodb://${test.server.uri()}/test`, {
         serverApi: null // TODO(NODE-3807): remove resetting serverApi when the usage of mongodb mock server is removed
       });
-      client.connect(function (err, client) {
-        expect(err).to.not.exist;
 
-        // Get a db with a new readPreference
-        var db1 = client.db('test', {
-          readPreference: new ReadPreference('secondary', null, { maxStalenessSeconds: 250 })
-        });
+      await client.connect();
 
-        db1
-          .collection('test')
-          .find({})
-          .toArray(function (err) {
-            expect(err).to.not.exist;
-            expect(test.checkCommand).to.containSubset({
-              $query: { find: 'test', filter: {} },
-              $readPreference: { mode: 'secondary', maxStalenessSeconds: 250 }
-            });
-
-            client.close(done);
-          });
+      // Get a db with a new readPreference
+      const db1 = client.db('test', {
+        readPreference: new ReadPreference('secondary', null, { maxStalenessSeconds: 250 })
+      });
+      await db1.collection('test').find({}).toArray();
+      expect(test.checkCommand).to.containSubset({
+        $readPreference: { mode: 'secondary', maxStalenessSeconds: 250 }
       });
+      await client.close();
     }
   });
 
@@ -120,35 +102,31 @@ describe('Max Staleness', function () {
       metadata: {
         requires: {
           generators: true,
-          topology: 'single'
+          topology: 'replicaset'
         }
       },
 
-      test: function (done) {
-        var self = this;
+      test: async function () {
+        const self = this;
         const configuration = this.configuration;
         const client = configuration.newClient(`mongodb://${test.server.uri()}/test`, {
           serverApi: null // TODO(NODE-3807): remove resetting serverApi when the usage of mongodb mock server is removed
         });
-        client.connect(function (err, client) {
-          expect(err).to.not.exist;
-          var db = client.db(self.configuration.db);
 
-          // Get a db with a new readPreference
-          db.collection('test', {
+        await client.connect();
+        const db = client.db(self.configuration.db);
+
+        // Get a db with a new readPreference
+        await db
+          .collection('test', {
             readPreference: new ReadPreference('secondary', null, { maxStalenessSeconds: 250 })
           })
-            .find({})
-            .toArray(function (err) {
-              expect(err).to.not.exist;
-              expect(test.checkCommand).to.containSubset({
-                $query: { find: 'test', filter: {} },
-                $readPreference: { mode: 'secondary', maxStalenessSeconds: 250 }
-              });
-
-              client.close(done);
-            });
+          .find({})
+          .toArray();
+        expect(test.checkCommand).to.containSubset({
+          $readPreference: { mode: 'secondary', maxStalenessSeconds: 250 }
         });
+        await client.close();
       }
     }
   );
@@ -157,35 +135,29 @@ describe('Max Staleness', function () {
     metadata: {
       requires: {
         generators: true,
-        topology: 'single'
+        topology: 'replicaset'
       }
     },
 
-    test: function (done) {
-      var self = this;
+    test: async function () {
+      const self = this;
       const configuration = this.configuration;
       const client = configuration.newClient(`mongodb://${test.server.uri()}/test`, {
         serverApi: null // TODO(NODE-3807): remove resetting serverApi when the usage of mongodb mock server is removed
       });
-      client.connect(function (err, client) {
-        expect(err).to.not.exist;
-        var db = client.db(self.configuration.db);
-        var readPreference = new ReadPreference('secondary', null, { maxStalenessSeconds: 250 });
 
-        // Get a db with a new readPreference
-        db.collection('test')
-          .find({})
-          .withReadPreference(readPreference)
-          .toArray(function (err) {
-            expect(err).to.not.exist;
-            expect(test.checkCommand).to.containSubset({
-              $query: { find: 'test', filter: {} },
-              $readPreference: { mode: 'secondary', maxStalenessSeconds: 250 }
-            });
-
-            client.close(done);
-          });
+      await client.connect();
+      const db = client.db(self.configuration.db);
+      const readPreference = new ReadPreference('secondary', null, { maxStalenessSeconds: 250 });
+
+      // Get a db with a new readPreference
+      await db.collection('test').find({}).withReadPreference(readPreference).toArray();
+
+      expect(test.checkCommand).to.containSubset({
+        $query: { find: 'test', filter: {} },
+        $readPreference: { mode: 'secondary', maxStalenessSeconds: 250 }
       });
+      await client.close();
     }
   });
 });

test/integration/run-command/run_command.spec.test.ts

@@ -2,10 +2,5 @@ import { loadSpecTests } from '../../spec';
 import { runUnifiedSuite } from '../../tools/unified-spec-runner/runner';
 
 describe('RunCommand spec', () => {
-  runUnifiedSuite(loadSpecTests('run-command'), test => {
-    if (test.description === 'does not attach $readPreference to given command on standalone') {
-      return 'TODO(NODE-5263): Do not send $readPreference to standalone servers';
-    }
-    return false;
-  });
+  runUnifiedSuite(loadSpecTests('run-command'));
 });