feat(query): cast $rename

lib/helpers/query/castUpdate.js

@@ -2,6 +2,7 @@
 
 const CastError = require('../../error/cast');
 const MongooseError = require('../../error/mongooseError');
+const SchemaString = require('../../schema/string');
 const StrictModeError = require('../../error/strict');
 const ValidationError = require('../../error/validation');
 const castNumber = require('../../cast/number');
@@ -307,6 +308,20 @@ function walkUpdatePath(schema, obj, op, options, context, filter, pref) {
           continue;
         }
 
+        hasKeys = true;
+      } else if (op === '$rename') {
+        const schematype = new SchemaString(`${prefix}${key}.$rename`);
+        try {
+          obj[key] = castUpdateVal(schematype, val, op, key, context, prefix + key);
+        } catch (error) {
+          aggregatedError = _appendError(error, context, key, aggregatedError);
+        }
+
+        if (obj[key] === void 0) {
+          delete obj[key];
+          continue;
+        }
+
         hasKeys = true;
       } else {
         const pathToCheck = (prefix + key);
@@ -372,10 +387,12 @@ function walkUpdatePath(schema, obj, op, options, context, filter, pref) {
           delete obj[key];
         }
       } else {
-        // gh-1845 temporary fix: ignore $rename. See gh-3027 for tracking
-        // improving this.
         if (op === '$rename') {
-          hasKeys = true;
+          if (obj[key] == null) {
+            throw new CastError('String', obj[key], `${prefix}${key}.$rename`);
+          }
+          const schematype = new SchemaString(`${prefix}${key}.$rename`);
+          obj[key] = schematype.castForQuery(null, obj[key], context);
           continue;
         }
 

test/model.updateOne.test.js

@@ -1078,9 +1078,28 @@ describe('model: updateOne:', function() {
       const Model = db.model('Test', schema);
 
       const update = { $rename: { foo: 'bar' } };
-      await Model.create({ foo: Date.now() });
-      const res = await Model.updateOne({}, update, { multi: true });
-      assert.equal(res.modifiedCount, 1);
+      const foo = Date.now();
+      const { _id } = await Model.create({ foo });
+      await Model.updateOne({}, update);
+      const doc = await Model.findById(_id);
+      assert.equal(doc.bar.valueOf(), foo.valueOf());
+    });
+
+    it('throws CastError if $rename fails to cast to string (gh-1845)', async function() {
+      const schema = new Schema({ foo: Date, bar: Date });
+      const Model = db.model('Test', schema);
+
+      let err = await Model.updateOne({}, { $rename: { foo: { prop: 'baz' } } }).then(() => null, err => err);
+      assert.equal(err.name, 'CastError');
+      assert.ok(err.message.includes('foo.$rename'));
+
+      err = await Model.updateOne({}, { $rename: { foo: null } }).then(() => null, err => err);
+      assert.equal(err.name, 'CastError');
+      assert.ok(err.message.includes('foo.$rename'));
+
+      err = await Model.updateOne({}, { $rename: { foo: undefined } }).then(() => null, err => err);
+      assert.equal(err.name, 'CastError');
+      assert.ok(err.message.includes('foo.$rename'));
     });
 
     it('allows objects with positional operator (gh-3185)', async function() {