`ValidationError: CastError: TypeError: path.split is not a function` with `refPath` as a function

[hasezoey]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

9.2.1

Node.js version

25.4.0

MongoDB server version

not relevant

Typescript version (if applicable)

5.9.3

Description

Trying to use refPath with a function and assign a document to that property in create, it results in a undescriptive ValidationError:

ValidationError: RefPathTest validation failed: ref: Cast to ObjectId failed for value "{
  propA: 'helloA',
  _id: new ObjectId('699069acf888d8b513312cd9'),
  __v: 0
}" (type model) at path "ref" because of "TypeError"

Upon further investigation, this is caused by a TypeError inside mongoose:

reason: TypeError: path.split is not a function
    at Schema.hasMixedParent (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/schema.js:1944:25)
    at Schema.path (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/schema.js:1288:23)
    at model.Document.$__path (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:2034:25)
    at model.Document.get (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1943:65)
    at /mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1435:29
    at model.$set (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1437:7)
    at model.$set (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1170:16)
    at model.Document (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:181:12)
    at model.Model (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:131:12)
    at new model (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:4805:15)
    at /mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:2747:20
    at Array.map (<anonymous>)
    at model.create (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:2735:34)
    at Object.<anonymous> (/mnt/ssd/projects/nodejs/typegoose/test/tests/ref.test.ts:484:40)
    at processTicksAndRejections (node:internal/process/task_queues:104:5),

I had also tried with other property names in case they were messing with "special properties", but the error remained the same.

Finally, note that assigning a document to a refPath property that is not a function works as expected (where it gets cast to the reftype, in this case ObjectId)

Full Error

ValidationError: RefPathTest validation failed: ref: Cast to ObjectId failed for value "{
  propA: 'helloA',
  _id: new ObjectId('699069acf888d8b513312cd9'),
  __v: 0
}" (type model) at path "ref" because of "TypeError"
    at model.Document.invalidate (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:3405:32)
    at model.$set (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1522:12)
    at model.$set (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1170:16)
    at model.Document (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:181:12)
    at model.Model (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:131:12)
    at new model (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:4805:15)
    at /mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:2747:20
    at Array.map (<anonymous>)
    at model.create (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:2735:34)
    at Object.<anonymous> (/mnt/ssd/projects/nodejs/typegoose/test/tests/ref.test.ts:484:40)
    at processTicksAndRejections (node:internal/process/task_queues:104:5) {
  errors: {
    ref: CastError: Cast to ObjectId failed for value "{
      propA: 'helloA',
      _id: new ObjectId('699069acf888d8b513312cd9'),
      __v: 0
    }" (type model) at path "ref" because of "TypeError"
        at model.$set (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1523:9)
        at model.$set (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1170:16)
        at model.Document (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:181:12)
        at model.Model (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:131:12)
        at new model (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:4805:15)
        at /mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:2747:20
        at Array.map (<anonymous>)
        at model.create (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:2735:34)
        at Object.<anonymous> (/mnt/ssd/projects/nodejs/typegoose/test/tests/ref.test.ts:484:40)
        at processTicksAndRejections (node:internal/process/task_queues:104:5) {
      stringValue: '"{\n' +
        "  propA: 'helloA',\n" +
        "  _id: new ObjectId('699069acf888d8b513312cd9'),\n" +
        '  __v: 0\n' +
        '}"',
      messageFormat: undefined,
      kind: 'ObjectId',
      value: [Object],
      path: 'ref',
      reason: TypeError: path.split is not a function
          at Schema.hasMixedParent (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/schema.js:1944:25)
          at Schema.path (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/schema.js:1288:23)
          at model.Document.$__path (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:2034:25)
          at model.Document.get (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1943:65)
          at /mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1435:29
          at model.$set (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1437:7)
          at model.$set (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:1170:16)
          at model.Document (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/document.js:181:12)
          at model.Model (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:131:12)
          at new model (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:4805:15)
          at /mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:2747:20
          at Array.map (<anonymous>)
          at model.create (/mnt/ssd/projects/nodejs/typegoose/node_modules/mongoose/lib/model.js:2735:34)
          at Object.<anonymous> (/mnt/ssd/projects/nodejs/typegoose/test/tests/ref.test.ts:484:40)
          at processTicksAndRejections (node:internal/process/task_queues:104:5),
      valueType: 'model'
    }
  },
  _message: 'RefPathTest validation failed'
}

Steps to Reproduce

const childASchema = new Schema({ propA: { required: true, type: String } });
const childBSchema = new Schema({ propB: { required: true, type: String } });
const ChildAModel = mongoose.model('ChildA', childASchema);
const ChildBModel = mongoose.model('ChildB', childBSchema);

const indexes = [ChildAModel.modelName, ChildBModel.modelName];

const refPathTestSchema = new mongoose.Schema({
  model: { required: true, min: 0, max: 1, type: Number },
  ref: {
    refPath: function () {
      return indexes[this.model];
    },
    type: mongoose.Types.ObjectId,
  },
});
const RefPathTestModel = mongoose.model('RefPathTest', refPathTestSchema);

const childAdoc = await ChildAModel.create({ propA: 'helloA' });
await ChildBModel.create({ propB: 'helloB' });

try {
  const doc = await RefPathTestModel.create({ model: 0, ref: childAdoc } as any);
} catch (err) {
  // necessary, as otherwise you dont get the actual error printed
  console.error(err);
  throw err;
}

Expected Behavior

No error, or a more descriptive error on what went wrong.

[hasezoey]

Additionally, if you change the ref: childAdoc to ref: childAdoc._id, it works in create without error, but if you try to do a populate later (on a new find), a new error comes up:

const found = await RefPathTestModel.findById(doc._id).populate('ref').orFail();

    TypeError: normalizedRefPath.split is not a function
      at _findRefPathForDiscriminators (node_modules/mongoose/lib/helpers/populate/getModelsMapForPopulate.js:716:36)
      at getModelsMapForPopulate (node_modules/mongoose/lib/helpers/populate/getModelsMapForPopulate.js:204:47)
      at _populatePath (node_modules/mongoose/lib/model.js:4361:21)
      at model.populate (node_modules/mongoose/lib/model.js:4328:21)
      at node_modules/mongoose/lib/query.js:2673:11
      at _init (node_modules/mongoose/lib/query.js:3351:5)
      at model.Document.init (node_modules/mongoose/lib/document.js:661:5)
      at model.Document.$init (node_modules/mongoose/lib/document.js:674:42)
      at Object.createModelAndInit (node_modules/mongoose/lib/queryHelpers.js:127:12)
      at completeOne (node_modules/mongoose/lib/query.js:3329:11)
      at model.Query.Query._completeOne (node_modules/mongoose/lib/query.js:2669:3)
      at node_modules/mongoose/lib/query.js:2733:10
      at model.Query._findOne (node_modules/mongoose/lib/query.js:2732:10)
      at model.Query.exec (node_modules/mongoose/lib/query.js:4687:63)
      at Object.<anonymous> (test/tests/ref.test.ts:491:17)

Am i somehow misunderstanding how refPath is meant to be used as a function?

[hasezoey]

Am i somehow misunderstanding how refPath is meant to be used as a function?

I just realized my mistake: i made the refPath function as a ref function (returning the model name instead of the path in the model itself). Still, in any case it likely should not return a TypeError(.split is not a function) for invalid paths.

[hasezoey]

Now that i have actually corrected my mistake (of mistaking refPath for ref), i have changed it to the following code, but still get the same errors:

const childASchema = new mongoose.Schema({ propA: { required: true, type: String } });
const childBSchema = new mongoose.Schema({ propB: { required: true, type: String } });
const ChildAModel = mongoose.model('ChildA', childASchema);
const ChildBModel = mongoose.model('ChildB', childBSchema);

const refPathTestSchema = new mongoose.Schema({
  model: { required: true, enum: [ChildAModel.modelName, ChildBModel.modelName], type: String },
  ref: {
    refPath: function () {
      return 'model';
    },
    type: mongoose.Types.ObjectId,
  },
});
const RefPathTestModel = mongoose.model('RefPathTest', refPathTestSchema);

const childAdoc = await ChildAModel.create({ propA: 'helloA' });
await ChildBModel.create({ propB: 'helloB' });

try {
  const doc = await RefPathTestModel.create({ model: ChildAModel.modelName, ref: childAdoc } as any);
} catch (err) {
  // necessary, as otherwise you dont get the actual error printed
  console.error(err);
  throw err;
}