feat: add forceRepopulate option for populate() to allow avoiding rep…

…opulating already populated docs

Fix #14979

lib/helpers/populate/getModelsMapForPopulate.js

@@ -54,6 +54,13 @@ module.exports = function getModelsMapForPopulate(model, docs, options) {
     doc = docs[i];
     let justOne = null;
 
+    if (doc.$__ != null && doc.populated(options.path)) {
+      const forceRepopulate = options.forceRepopulate != null ? options.forceRepopulate : doc.constructor.base.options.forceRepopulate;
+      if (forceRepopulate === false) {
+        continue;
+      }
+    }
+
     const docSchema = doc != null && doc.$__ != null ? doc.$__schema : modelSchema;
     schema = getSchemaTypes(model, docSchema, doc, options.path);
 

lib/model.js

@@ -4199,6 +4199,7 @@ Model.validate = async function validate(obj, pathsOrOptions, context) {
  * - options: optional query options like sort, limit, etc
  * - justOne: optional boolean, if true Mongoose will always set `path` to a document, or `null` if no document was found. If false, Mongoose will always set `path` to an array, which will be empty if no documents are found. Inferred from schema by default.
  * - strictPopulate: optional boolean, set to `false` to allow populating paths that aren't in the schema.
+ * - forceRepopulate: optional boolean, defaults to `true`. Set to `false` to prevent Mongoose from repopulating paths that are already populated
  *
  * #### Example:
  *
@@ -4235,6 +4236,7 @@ Model.validate = async function validate(obj, pathsOrOptions, context) {
  * @param {Boolean} [options.strictPopulate=true] Set to false to allow populating paths that aren't defined in the given model's schema.
  * @param {Object} [options.options=null] Additional options like `limit` and `lean`.
  * @param {Function} [options.transform=null] Function that Mongoose will call on every populated document that allows you to transform the populated document.
+ * @param {Boolean} [options.forceRepopulate=true] Set to `false` to prevent Mongoose from repopulating paths that are already populated
  * @param {Function} [callback(err,doc)] Optional callback, executed upon completion. Receives `err` and the `doc(s)`.
  * @return {Promise}
  * @api public

lib/validOptions.js

@@ -17,6 +17,7 @@ const VALID_OPTIONS = Object.freeze([
   'cloneSchemas',
   'createInitialConnection',
   'debug',
+  'forceRepopulate',
   'id',
   'timestamps.createdAt.immutable',
   'maxTimeMS',

test/model.populate.test.js

@@ -11279,4 +11279,89 @@ describe('model: populate:', function() {
     assert.strictEqual(doc.node.length, 1);
     assert.strictEqual(doc.node[0]._id, '65c7953e-c6e9-4c2f-8328-fe2de7df560d');
   });
+
+  it('avoids repopulating if forceRepopulate disabled (gh-14979)', async function() {
+    const ChildSchema = new Schema({ name: String });
+    const ParentSchema = new Schema({
+      children: [{ type: Schema.Types.ObjectId, ref: 'Child' }],
+      child: { type: 'ObjectId', ref: 'Child' }
+    });
+
+    const Child = db.model('Child', ChildSchema);
+    const Parent = db.model('Parent', ParentSchema);
+
+    const child = await Child.create({ name: 'Child test' });
+    let parent = await Parent.create({ child: child._id, children: [child._id] });
+
+    parent = await Parent.findOne({ _id: parent._id }).populate(['child', 'children']).orFail();
+    child.name = 'Child test updated 1';
+    await child.save();
+
+    await parent.populate({ path: 'child', forceRepopulate: false });
+    await parent.populate({ path: 'children', forceRepopulate: false });
+    assert.equal(parent.child.name, 'Child test');
+    assert.equal(parent.children[0].name, 'Child test');
+
+    await Parent.populate([parent], { path: 'child', forceRepopulate: false });
+    await Parent.populate([parent], { path: 'children', forceRepopulate: false });
+    assert.equal(parent.child.name, 'Child test');
+    assert.equal(parent.children[0].name, 'Child test');
+
+    parent.depopulate('child');
+    parent.depopulate('children');
+    await parent.populate({ path: 'child', forceRepopulate: false });
+    await parent.populate({ path: 'children', forceRepopulate: false });
+    assert.equal(parent.child.name, 'Child test updated 1');
+    assert.equal(parent.children[0].name, 'Child test updated 1');
+  });
+
+  it('handles forceRepopulate as a global option (gh-14979)', async function() {
+    const m = new mongoose.Mongoose();
+    m.set('forceRepopulate', false);
+    await m.connect(start.uri);
+    const ChildSchema = new m.Schema({ name: String });
+    const ParentSchema = new m.Schema({
+      children: [{ type: Schema.Types.ObjectId, ref: 'Child' }],
+      child: { type: 'ObjectId', ref: 'Child' }
+    });
+
+    const Child = m.model('Child', ChildSchema);
+    const Parent = m.model('Parent', ParentSchema);
+
+    const child = await Child.create({ name: 'Child test' });
+    let parent = await Parent.create({ child: child._id, children: [child._id] });
+
+    parent = await Parent.findOne({ _id: parent._id }).populate(['child', 'children']).orFail();
+    child.name = 'Child test updated 1';
+    await child.save();
+
+    await parent.populate({ path: 'child' });
+    await parent.populate({ path: 'children' });
+    assert.equal(parent.child.name, 'Child test');
+    assert.equal(parent.children[0].name, 'Child test');
+
+    await Parent.populate([parent], { path: 'child' });
+    await Parent.populate([parent], { path: 'children' });
+    assert.equal(parent.child.name, 'Child test');
+    assert.equal(parent.children[0].name, 'Child test');
+
+    parent.depopulate('child');
+    parent.depopulate('children');
+    await parent.populate({ path: 'child' });
+    await parent.populate({ path: 'children' });
+    assert.equal(parent.child.name, 'Child test updated 1');
+    assert.equal(parent.children[0].name, 'Child test updated 1');
+
+    child.name = 'Child test updated 2';
+    await child.save();
+
+    parent.depopulate('child');
+    parent.depopulate('children');
+    await parent.populate({ path: 'child', forceRepopulate: true });
+    await parent.populate({ path: 'children', forceRepopulate: true });
+    assert.equal(parent.child.name, 'Child test updated 2');
+    assert.equal(parent.children[0].name, 'Child test updated 2');
+
+    await m.disconnect();
+  });
 });

types/populate.d.ts

@@ -37,6 +37,8 @@ declare module 'mongoose' {
     localField?: string;
     /** Overwrite the schema-level foreign field to populate on if this is a populated virtual. */
     foreignField?: string;
+    /** Set to `false` to prevent Mongoose from repopulating paths that are already populated */
+    forceRepopulate?: boolean;
   }
 
   interface PopulateOption {