From ca3a738021a2eb061af0622882135cf5c97f4cd0 Mon Sep 17 00:00:00 2001
From: Suliman Abdulrazzaq <suliman9000a@gmail.com>
Date: Fri, 25 Sep 2026 14:17:42 +0300
Subject: [PATCH] fix(query): replace {MODEL} in cast error messages from
 update and bulkWrite() casting

---
 lib/helpers/model/castBulkWrite.js | 23 ++++++++++++++++-----
 lib/helpers/query/castUpdate.js    |  8 ++++++++
 test/schema.test.js                | 33 ++++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/lib/helpers/model/castBulkWrite.js b/lib/helpers/model/castBulkWrite.js
index bf0dd491434..d13a5b96cfa 100644
--- a/lib/helpers/model/castBulkWrite.js
+++ b/lib/helpers/model/castBulkWrite.js
@@ -149,7 +149,7 @@ module.exports.castUpdateOne = function castUpdateOne(originalModel, updateOne,
     model.schema.options.versionKey
   );
 
-  updateOne['filter'] = cast(model.schema, updateOne['filter'], {
+  updateOne['filter'] = _castFilter(model, updateOne['filter'], {
     strict: strict,
     upsert: updateOne.upsert
   });
@@ -210,7 +210,7 @@ module.exports.castUpdateMany = function castUpdateMany(originalModel, updateMan
     model.schema.options.versionKey
   );
 
-  updateMany['filter'] = cast(model.schema, updateMany['filter'], {
+  updateMany['filter'] = _castFilter(model, updateMany['filter'], {
     strict: strict,
     upsert: updateMany.upsert
   });
@@ -230,7 +230,7 @@ module.exports.castReplaceOne = async function castReplaceOne(originalModel, rep
   const strict = options.strict ?? model.schema.options.strict;
 
   _addDiscriminatorToObject(schema, replaceOne['filter']);
-  replaceOne['filter'] = cast(model.schema, replaceOne['filter'], {
+  replaceOne['filter'] = _castFilter(model, replaceOne['filter'], {
     strict: strict,
     upsert: replaceOne.upsert
   });
@@ -264,7 +264,7 @@ module.exports.castDeleteOne = function castDeleteOne(originalModel, deleteOne)
 
   _addDiscriminatorToObject(schema, deleteOne['filter']);
 
-  deleteOne['filter'] = cast(model.schema, deleteOne['filter']);
+  deleteOne['filter'] = _castFilter(model, deleteOne['filter']);
 };
 
 module.exports.castDeleteMany = function castDeleteMany(originalModel, deleteMany) {
@@ -273,7 +273,7 @@ module.exports.castDeleteMany = function castDeleteMany(originalModel, deleteMan
 
   _addDiscriminatorToObject(schema, deleteMany['filter']);
 
-  deleteMany['filter'] = cast(model.schema, deleteMany['filter']);
+  deleteMany['filter'] = _castFilter(model, deleteMany['filter']);
 };
 
 module.exports.cast = {
@@ -285,6 +285,19 @@ module.exports.cast = {
   deleteMany: module.exports.castDeleteMany
 };
 
+function _castFilter(model, filter, options) {
+  try {
+    return cast(model.schema, filter, options);
+  } catch (err) {
+    // Set the model on cast errors so `{MODEL}` gets replaced, like it is for
+    // query filter casting (gh-8300)
+    if (typeof err.setModel === 'function') {
+      err.setModel(model);
+    }
+    throw err;
+  }
+}
+
 function _addDiscriminatorToObject(schema, obj) {
   if (schema == null) {
     return;
diff --git a/lib/helpers/query/castUpdate.js b/lib/helpers/query/castUpdate.js
index 6d6e6c3f902..511be60049f 100644
--- a/lib/helpers/query/castUpdate.js
+++ b/lib/helpers/query/castUpdate.js
@@ -499,6 +499,14 @@ function walkUpdatePath(schema, obj, op, options, context, filter, prefix) {
  */
 
 function _appendError(error, query, key, aggregatedError) {
+  // Set the model on cast errors so `{MODEL}` gets replaced, like it is for
+  // query filter casting and document validation (gh-8300). `query` is a
+  // Query, or the model itself when casting a `bulkWrite()` operation.
+  const model = query?.modelName != null ? query : query?.model;
+  if (model != null && typeof error.setModel === 'function') {
+    error.setModel(model);
+  }
+
   if (typeof query !== 'object' || !query.options.multipleCastError) {
     throw error;
   }
diff --git a/test/schema.test.js b/test/schema.test.js
index b9251763f50..30729c399d1 100644
--- a/test/schema.test.js
+++ b/test/schema.test.js
@@ -2827,6 +2827,39 @@ describe('schema', function() {
           '"twenty" is not a valid number for model gh8300_castObject'
       );
     });
+
+    it('replaces {MODEL} with model name in update and bulkWrite() cast errors', async function() {
+      const schema = Schema({
+        age: {
+          type: Number,
+          cast: '{VALUE} is not a valid number for model {MODEL}'
+        }
+      });
+      const Test = db.model('gh8300_update', schema);
+      const message = '"twenty" is not a valid number for model gh8300_update';
+
+      const isCastError = err => err.name === 'CastError' && err.message === message;
+
+      await assert.rejects(() => Test.updateOne({}, { age: 'twenty' }), isCastError);
+      await assert.rejects(() => Test.updateMany({}, { $set: { age: 'twenty' } }), isCastError);
+      await assert.rejects(() => Test.findOneAndUpdate({}, { age: 'twenty' }), isCastError);
+
+      await assert.rejects(
+        () => Test.updateOne({}, { age: 'twenty' }, { multipleCastError: true }),
+        err => err.name === 'ValidationError' &&
+          err.errors['age'].message === message &&
+          err.message === 'Validation failed: age: ' + message
+      );
+
+      await assert.rejects(
+        () => Test.bulkWrite([{ updateOne: { filter: {}, update: { age: 'twenty' } } }]),
+        isCastError
+      );
+      await assert.rejects(
+        () => Test.bulkWrite([{ deleteOne: { filter: { age: 'twenty' } } }]),
+        isCastError
+      );
+    });
   });
 
   it('copies `.add()`-ed paths when calling `.add()` with a schema argument (gh-8429)', function() {