Merge pull request #15567 from Automattic/vkarpov15/gh-15553

fix(query): propagate read preference to populate if `read()` called after `populate()`

Author: vkarpov15

lib/query.js

@@ -2133,6 +2133,29 @@ Query.prototype._optionsForExec = function(model) {
     }
   }
 
+  if (this._mongooseOptions.populate) {
+    if (options.readPreference) {
+      for (const pop of Object.values(this._mongooseOptions.populate)) {
+        if (pop.options?.readPreference === undefined) {
+          if (!pop.options) {
+            pop.options = {};
+          }
+          pop.options.readPreference = options.readPreference;
+        }
+      }
+    }
+    if (options.readConcern) {
+      for (const pop of Object.values(this._mongooseOptions.populate)) {
+        if (pop.options?.readConcern === undefined) {
+          if (!pop.options) {
+            pop.options = {};
+          }
+          pop.options.readConcern = options.readConcern;
+        }
+      }
+    }
+  }
+
   return options;
 };
 
@@ -4918,24 +4941,6 @@ Query.prototype.populate = function() {
 
   const res = utils.populate.apply(null, args);
 
-  // Propagate readConcern and readPreference and lean from parent query,
-  // unless one already specified
-  if (this.options != null) {
-    const readConcern = this.options.readConcern;
-    const readPref = this.options.readPreference;
-
-    for (const populateOptions of res) {
-      if (readConcern != null && (populateOptions && populateOptions.options && populateOptions.options.readConcern) == null) {
-        populateOptions.options = populateOptions.options || {};
-        populateOptions.options.readConcern = readConcern;
-      }
-      if (readPref != null && (populateOptions && populateOptions.options && populateOptions.options.readPreference) == null) {
-        populateOptions.options = populateOptions.options || {};
-        populateOptions.options.readPreference = readPref;
-      }
-    }
-  }
-
   const opts = this._mongooseOptions;
 
   if (opts.lean != null) {

test/model.populate.test.js

@@ -5569,6 +5569,7 @@ describe('model: populate:', function() {
         const Model = db.model('Test1', schema);
 
         const q = Model.find().read('secondaryPreferred').populate('ref');
+        await q.exec();
         assert.equal(q._mongooseOptions.populate['ref'].options.readPreference.mode,
           'secondaryPreferred');
       });

test/query.test.js

@@ -4469,6 +4469,51 @@ describe('Query', function() {
     });
   });
 
+  it('propagates readPreference to populate options if read() is called after populate() (gh-15553)', async function() {
+    const schema = new Schema({ name: String, age: Number, friends: [{ type: 'ObjectId', ref: 'Person' }] });
+    const Person = db.model('Person', schema);
+
+    let query = Person.find({}).populate('friends');
+    query.read('secondaryPreferred');
+    await query.exec();
+    assert.strictEqual(query._mongooseOptions.populate.friends.options.readPreference.mode, 'secondaryPreferred');
+
+    query = Person.find({}).read('secondary').populate('friends');
+    query.read('secondaryPreferred');
+    await query.exec();
+    assert.strictEqual(query._mongooseOptions.populate.friends.options.readPreference.mode, 'secondaryPreferred');
+
+    query = Person.find({}).read('secondaryPreferred').populate('friends');
+    await query.exec();
+    assert.strictEqual(query._mongooseOptions.populate.friends.options.readPreference.mode, 'secondaryPreferred');
+
+    query = Person.find({}).read('primaryPreferred').populate({ path: 'friends', options: { readPreference: 'secondaryPreferred' } });
+    await query.exec();
+    assert.strictEqual(query._mongooseOptions.populate.friends.options.readPreference, 'secondaryPreferred');
+  });
+
+  it('propagates readConcern to populate options if readConcern() is called after populate() (gh-15553)', async function() {
+    const schema = new Schema({ name: String, age: Number, friends: [{ type: 'ObjectId', ref: 'Person' }] });
+    const Person = db.model('Person', schema);
+
+    let query = Person.find({}).populate('friends');
+    query.readConcern('majority');
+    await query.exec();
+    assert.strictEqual(query._mongooseOptions.populate.friends.options.readConcern.level, 'majority');
+
+    query = Person.find({}).readConcern('local').populate('friends');
+    query.readConcern('majority');
+    await query.exec();
+    assert.strictEqual(query._mongooseOptions.populate.friends.options.readConcern.level, 'majority');
+
+    query = Person.find({}).readConcern('majority').populate('friends');
+    await query.exec();
+    assert.strictEqual(query._mongooseOptions.populate.friends.options.readConcern.level, 'majority');
+
+    query = Person.find({}).readConcern('majority').populate({ path: 'friends', options: { readConcern: 'local' } });
+    await query.exec();
+    assert.strictEqual(query._mongooseOptions.populate.friends.options.readConcern, 'local');
+  });
 
   describe('Query with requireFilter', function() {
     let Person;