fix: correct writeError index when insertMany() with ordered: false, …

…rawResult: true with mixed validation error and write error re: #12791

lib/model.js

@@ -3452,10 +3452,20 @@ Model.$__insertMany = function(arr, options, callback) {
       callback(error, null);
       return;
     }
+
+    const originalDocIndex = new Map();
+    const validDocIndexToOriginalIndex = new Map();
+    for (let i = 0; i < docs.length; ++i) {
+      originalDocIndex.set(docs[i], i);
+    }
+
     // We filter all failed pre-validations by removing nulls
     const docAttributes = docs.filter(function(doc) {
       return doc != null;
     });
+    for (let i = 0; i < docAttributes.length; ++i) {
+      validDocIndexToOriginalIndex.set(i, originalDocIndex.get(docAttributes[i]));
+    }
 
     // Make sure validation errors are in the same order as the
     // original documents, so if both doc1 and doc2 both fail validation,
@@ -3506,6 +3516,13 @@ Model.$__insertMany = function(arr, options, callback) {
         // `insertedDocs` is a Mongoose-specific property
         const erroredIndexes = new Set((error && error.writeErrors || []).map(err => err.index));
 
+        for (let i = 0; i < error.writeErrors.length; ++i) {
+          error.writeErrors[i] = {
+            ...error.writeErrors[i],
+            index: validDocIndexToOriginalIndex.get(error.writeErrors[i].index)
+          };
+        }
+
         let firstErroredIndex = -1;
         error.insertedDocs = docAttributes.
           filter((doc, i) => {
@@ -3529,6 +3546,12 @@ Model.$__insertMany = function(arr, options, callback) {
             return doc;
           });
 
+        if (rawResult && ordered === false) {
+          error.mongoose = {
+            validationErrors: validationErrors
+          };
+        }
+
         callback(error, null);
         return;
       }

test/model.test.js

@@ -4823,6 +4823,35 @@ describe('Model', function() {
       assert.ok(!res.mongoose.validationErrors[1].errors['name']);
     });
 
+    it('insertMany() validation error with ordered false and rawResult for mixed write and validation error (gh-12791)', async function() {
+      const schema = new Schema({
+        name: { type: String, required: true, unique: true },
+        year: { type: Number, required: true }
+      });
+      const Movie = db.model('Movie', schema);
+      await Movie.init();
+
+      const arr = [
+        { foo: 'The Phantom Menace', year: 1999 },
+        { name: 'The Force Awakens', bar: 2015 },
+        { name: 'The Empire Strikes Back', year: 1980 },
+        { name: 'The Empire Strikes Back', year: 1980 }
+      ];
+      const opts = { ordered: false, rawResult: true };
+      const err = await Movie.insertMany(arr, opts).then(() => null, err => err);
+
+      assert.ok(err);
+      assert.equal(err.insertedDocs.length, 1);
+      assert.equal(err.insertedDocs[0].name, 'The Empire Strikes Back');
+      assert.equal(err.writeErrors.length, 1);
+      assert.equal(err.writeErrors[0].index, 3);
+      assert.equal(err.mongoose.validationErrors.length, 2);
+      assert.ok(err.mongoose.validationErrors[0].errors['name']);
+      assert.ok(!err.mongoose.validationErrors[0].errors['year']);
+      assert.ok(err.mongoose.validationErrors[1].errors['year']);
+      assert.ok(!err.mongoose.validationErrors[1].errors['name']);
+    });
+
     it('insertMany() populate option (gh-9720)', async function() {
       const schema = new Schema({
         name: { type: String, required: true }