deprecate top level write concern fields

Author: HanaPearlman

lib/db.js

@@ -72,6 +72,7 @@ const legalOptionNames = [
   'wtimeout',
   'fsync',
   'j',
+  'writeConcern',
   'readPreference',
   'readPreferenceTags',
   'native_parser',

lib/operations/connect.js

@@ -14,6 +14,7 @@ const Server = require('../topologies/server');
 const ServerSessionPool = require('../core').Sessions.ServerSessionPool;
 const emitDeprecationWarning = require('../utils').emitDeprecationWarning;
 const fs = require('fs');
+const WriteConcern = require('../write_concern');
 const BSON = require('../core/connection/utils').retrieveBSON();
 const CMAP_EVENT_NAMES = require('../cmap/events').CMAP_EVENT_NAMES;
 
@@ -105,6 +106,7 @@ const validOptionNames = [
   'w',
   'wtimeout',
   'j',
+  'writeConcern',
   'forceServerObjectId',
   'serializeFunctions',
   'ignoreUndefined',
@@ -300,9 +302,9 @@ function connect(mongoClient, url, options, callback) {
       delete _finalOptions.db_options.auth;
     }
 
-    // `journal` should be translated to `j` for the driver
     if (_finalOptions.journal != null) {
-      _finalOptions.j = _finalOptions.journal;
+      if (_finalOptions.writeConcern == null) _finalOptions.writeConcern = {};
+      _finalOptions.writeConcern.j = _finalOptions.journal;
       _finalOptions.journal = undefined;
     }
 
@@ -616,9 +618,12 @@ function createUnifiedOptions(finalOptions, options) {
     'mongos_options'
   ];
   const noMerge = ['readconcern', 'compression', 'autoencryption'];
+  const skip = ['w', 'wtimeout', 'j', 'fsync', 'writeConcern'];
 
   for (const name in options) {
-    if (noMerge.indexOf(name.toLowerCase()) !== -1) {
+    if (skip.indexOf(name.toLowerCase()) !== -1) {
+      continue;
+    } else if (noMerge.indexOf(name.toLowerCase()) !== -1) {
       finalOptions[name] = options[name];
     } else if (childOptions.indexOf(name.toLowerCase()) !== -1) {
       finalOptions = mergeOptions(finalOptions, options[name], false);
@@ -636,6 +641,18 @@ function createUnifiedOptions(finalOptions, options) {
     }
   }
 
+  // Handle write concern keys separately, since `options` may have the keys at the top level or
+  // under `options.writeConcern`. The final merged keys will be under `finalOptions.writeConcern`.
+  // `fromOptions` will warn if `options` is using deprecated write concern options
+  const optionsWriteConcern = WriteConcern.fromOptions(options);
+  if (optionsWriteConcern) {
+    finalOptions.writeConcern = Object.assign(
+      {},
+      finalOptions.writeConcern,
+      WriteConcern.fromOptions(options)
+    );
+  }
+
   return finalOptions;
 }
 
@@ -760,12 +777,29 @@ function transformUrlOptions(_object) {
 
   if (object.wTimeoutMS) {
     object.wtimeout = object.wTimeoutMS;
+    object.wTimeoutMS = undefined;
+  }
+
+  if (object.journal) {
+    object.j = object.journal;
+    object.journal = undefined;
   }
 
   if (_object.srvHost) {
     object.srvHost = _object.srvHost;
   }
 
+  // Any write concern options from the URL will be top-level, so we manually
+  // move them options under `object.writeConcern`
+  const wcKeys = ['w', 'wtimeout', 'j', 'fsync'];
+  for (const key of wcKeys) {
+    if (object[key] !== undefined) {
+      if (object.writeConcern === undefined) object.writeConcern = {};
+      object.writeConcern[key] = object[key];
+      object[key] = undefined;
+    }
+  }
+
   return object;
 }
 

lib/write_concern.js

@@ -69,6 +69,9 @@ class WriteConcern {
       );
     }
 
+    console.warn(
+      `Top-level use of w, wtimeout, j, and fsync is deprecated. Use writeConcern instead.`
+    );
     return new WriteConcern(options.w, options.wtimeout, options.j, options.fsync);
   }
 }

test/functional/write_concern.test.js

@@ -26,7 +26,7 @@ describe('Write Concern', function() {
     function journalOptionTest(client, events, done) {
       expect(client).to.have.nested.property('s.options');
       const clientOptions = client.s.options;
-      expect(clientOptions).to.containSubset({ j: true });
+      expect(clientOptions).to.containSubset({ writeConcern: { j: true } });
       client
         .db('test')
         .collection('test')