fix(cursor): set readPreference for cursor.count

Fixes NODE-1581

lib/operations/collection_ops.js

@@ -175,33 +175,14 @@ function checkForAtomicOperators(update) {
 function count(coll, query, options, callback) {
  if (typeof options === 'function') (callback = options), (options = {});
  options = Object.assign({}, options);
+ options.collectionName = coll.s.name;
 
- const skip = options.skip;
- const limit = options.limit;
- const hint = options.hint;
- const maxTimeMS = options.maxTimeMS;
- query = query || {};
-
- // Final query
- const cmd = {
- count: coll.s.name,
- query: query
- };
-
- // Add limit, skip and maxTimeMS if defined
- if (typeof skip === 'number') cmd.skip = skip;
- if (typeof limit === 'number') cmd.limit = limit;
- if (typeof maxTimeMS === 'number') cmd.maxTimeMS = maxTimeMS;
- if (hint) cmd.hint = hint;
-
- // Ensure we have the right read preference inheritance
- options.readPreference = resolveReadPreference(options, { db: coll.s.db, collection: coll });
-
- // Do we have a readConcern specified
- decorateWithReadConcern(cmd, coll, options);
+ options.readPreference = resolveReadPreference(options, {
+ db: coll.s.db,
+ collection: coll
+ });
 
- // Have we specified collation
- decorateWithCollation(cmd, coll, options);
+ const cmd = buildCountCommand(coll, query, options);
 
  executeCommand(coll.s.db, cmd, options, (err, result) => {
  if (err) return handleCallback(callback, err);
@@ -236,6 +217,51 @@ function countDocuments(coll, query, options, callback) {
  });
 }
 
+/**
+ * Build the count command.
+ *
+ * @method
+ * @param {collectionOrCursor} an instance of a collection or cursor
+ * @param {object} query The query for the count.
+ * @param {object} [options] Optional settings. See Collection.prototype.count and Cursor.prototype.count for a list of options.
+ */
+function buildCountCommand(collectionOrCursor, query, options) {
+ const skip = options.skip;
+ const limit = options.limit;
+ let hint = options.hint;
+ const maxTimeMS = options.maxTimeMS;
+ query = query || {};
+
+ // Final query
+ const cmd = {
+ count: options.collectionName,
+ query: query
+ };
+
+ // check if collectionOrCursor is a cursor by using cursor.s.numberOfRetries
+ if (collectionOrCursor.s.numberOfRetries) {
+ if (collectionOrCursor.s.options.hint) {
+ hint = collectionOrCursor.s.options.hint;
+ } else if (collectionOrCursor.s.cmd.hint) {
+ hint = collectionOrCursor.s.cmd.hint;
+ }
+ decorateWithCollation(cmd, collectionOrCursor, collectionOrCursor.s.cmd);
+ } else {
+ decorateWithCollation(cmd, collectionOrCursor, options);
+ }
+
+ // Add limit, skip and maxTimeMS if defined
+ if (typeof skip === 'number') cmd.skip = skip;
+ if (typeof limit === 'number') cmd.limit = limit;
+ if (typeof maxTimeMS === 'number') cmd.maxTimeMS = maxTimeMS;
+ if (hint) cmd.hint = hint;
+
+ // Do we have a readConcern specified
+ decorateWithReadConcern(cmd, collectionOrCursor);
+
+ return cmd;
+}
+
 /**
  * Create an index on the db and collection.
  *
@@ -1391,6 +1417,7 @@ module.exports = {
  checkForAtomicOperators,
  count,
  countDocuments,
+ buildCountCommand,
  createIndex,
  createIndexes,
  deleteMany,

lib/operations/cursor_ops.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const decorateWithCollation = require('../utils').decorateWithCollation;
+const buildCountCommand = require('./collection_ops').buildCountCommand;
 const formattedOrderClause = require('../utils').formattedOrderClause;
 const handleCallback = require('../utils').handleCallback;
 const MongoError = require('mongodb-core').MongoError;
@@ -21,37 +21,30 @@ function count(cursor, applySkipLimit, opts, callback) {
  if (typeof cursor.cursorLimit() === 'number') opts.limit = cursor.cursorLimit();
  }
 
- // Command
- const delimiter = cursor.s.ns.indexOf('.');
-
- let command = {
- count: cursor.s.ns.substr(delimiter + 1),
- query: cursor.s.cmd.query
- };
-
- // Apply a readConcern if set
- if (cursor.s.cmd.readConcern) {
- command.readConcern = cursor.s.cmd.readConcern;
+ // Ensure we have the right read preference inheritance
+ if (opts.readPreference) {
+ cursor.setReadPreference(opts.readPreference);
  }
 
- // Apply a hint if set
- if (cursor.s.cmd.hint) {
- command.hint = cursor.s.cmd.hint;
+ if (
+ typeof opts.maxTimeMS !== 'number' &&
+ cursor.s.cmd &&
+ typeof cursor.s.cmd.maxTimeMS === 'number'
+ ) {
+ opts.maxTimeMS = cursor.s.cmd.maxTimeMS;
  }
 
- // Apply a collation if set
- decorateWithCollation(command, cursor, cursor.s.cmd);
+ let options = {};
+ options.skip = opts.skip;
+ options.limit = opts.limit;
+ options.hint = opts.hint;
+ options.maxTimeMS = opts.maxTimeMS;
 
- if (typeof opts.maxTimeMS === 'number') {
- command.maxTimeMS = opts.maxTimeMS;
- } else if (cursor.s.cmd && typeof cursor.s.cmd.maxTimeMS === 'number') {
- command.maxTimeMS = cursor.s.cmd.maxTimeMS;
- }
+ // Command
+ const delimiter = cursor.s.ns.indexOf('.');
+ options.collectionName = cursor.s.ns.substr(delimiter + 1);
 
- // Merge in any options
- if (opts.skip) command.skip = opts.skip;
- if (opts.limit) command.limit = opts.limit;
- if (cursor.s.options.hint) command.hint = cursor.s.options.hint;
+ const command = buildCountCommand(cursor, cursor.s.cmd.query, options);
 
  // Set cursor server to the same as the topology
  cursor.server = cursor.topology.s.coreTopology;

test/functional/cursor_tests.js

@@ -5,6 +5,7 @@ const fs = require('fs');
 const expect = require('chai').expect;
 const Long = require('bson').Long;
 const sinon = require('sinon');
+const ReadPreference = require('mongodb-core').ReadPreference;
 
 describe('Cursor', function() {
  before(function() {
@@ -280,6 +281,37 @@ describe('Cursor', function() {
  }
  });
 
+ it('Should correctly execute cursor count with secondary readPreference', {
+ // Add a tag that our runner can trigger on
+ // in this case we are setting that node needs to be higher than 0.10.X to run
+ metadata: {
+ requires: { topology: 'replicaset' }
+ },
+
+ // The actual test we wish to run
+ test: function(done) {
+ const configuration = this.configuration;
+ const client = configuration.newClient(configuration.writeConcernMax(), { poolSize: 1 });
+
+ client.connect((err, client) => {
+ const db = client.db(configuration.db);
+
+ const internalClientCursor = sinon.spy(client.topology.s.coreTopology, 'cursor');
+ const expectedReadPreference = new ReadPreference(ReadPreference.SECONDARY);
+
+ const cursor = db.collection('countTEST').find({ qty: { $gt: 4 } });
+ cursor.count(true, { readPreference: ReadPreference.SECONDARY }, err => {
+ expect(err).to.be.null;
+ expect(internalClientCursor.getCall(0).args[2])
+ .to.have.nested.property('readPreference')
+ .that.deep.equals(expectedReadPreference);
+ client.close();
+ done();
+ });
+ });
+ }
+ });
+
  /**
  * @ignore
  * @api private