refactor: pass parent schema to SchemaType constructors in interpretAsType to make implementing custom container types easier #15700

vkarpov15 · 2025-10-27T18:34:04Z

Summary

Implementing your own container type is a pain unless the container type happens to extend from Array, because otherwise you need to handle interpreting of by yourself. For example, imagine { type: Set, of: { type: String, required: true } } - right now anyone implementing a set schematype would have to re-implement interpretAsType semantics themselves. We had to do a bit of a hack to avoid having to re-implement interpretAsType for unions, but with this fix we can remove the hack as well.

Examples

…sType to make implementing custom container types easier

Copilot

Pull Request Overview

This refactor improves the extensibility of custom container types in Mongoose by passing the parent schema as a parameter to SchemaType constructors. Previously, implementing custom container types that needed to interpret nested schemas (like { type: Set, of: { type: String } }) required re-implementing interpretAsType logic or using workarounds like the options.parentSchema hack used in the Union type.

Key changes:

Added parentSchema parameter to all SchemaType constructors via interpretAsType
Removed the Union-specific hack that attached parent schema to options
Union type now receives parent schema directly as a constructor parameter

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
lib/schema.js	Updated `interpretAsType` to pass `this` (parent schema) as fourth parameter to SchemaType constructors, removing Union-specific workaround
lib/schema/union.js	Modified Union constructor to accept `parentSchema` parameter instead of accessing it from options

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lib/schema/union.js

hasezoey

LGTM, though it seems Github CI's Node 22 does not like some change here, though any other version just works.

The CI errors in question

Runner: Node 22 MongoDB 6.0.15 OS ubuntu-22.04
Full Node Version in runner: 22.21.0

  1) Double
       cast errors
         when a non-numeric string is provided to an Double field
           throws a CastError upon validation:
      AssertionError [ERR_ASSERTION]: 'Cast to Double failed for value "helloworld" (type string) at path "myDouble" because of "SyntaxError"' == 'Cast to Double failed for value "helloworld" (type string) at path "myDouble"'
      + expected - actual
      -Cast to Double failed for value "helloworld" (type string) at path "myDouble" because of "SyntaxError"
      +Cast to Double failed for value "helloworld" (type string) at path "myDouble"
      
      at Context.<anonymous> (test/double.test.js:284:16)
      at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

  2) Int32
       cast errors
         when a non-integer decimal input is provided to an Int32 field
           throws a CastError upon validation:
      AssertionError [ERR_ASSERTION]: 'Cast to Int32 failed for value "-42.4" (type number) at path "myInt" because of "SyntaxError"' == 'Cast to Int32 failed for value "-42.4" (type number) at path "myInt"'
      + expected - actual
      -Cast to Int32 failed for value "-42.4" (type number) at path "myInt" because of "SyntaxError"
      +Cast to Int32 failed for value "-42.4" (type number) at path "myInt"
      
      at Context.<anonymous> (test/int32.test.js:304:16)
      at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

  3) Int32
       cast errors
         when a non-numeric string is provided to an Int32 field
           throws a CastError upon validation:
      AssertionError [ERR_ASSERTION]: 'Cast to Int32 failed for value "helloworld" (type string) at path "myInt" because of "SyntaxError"' == 'Cast to Int32 failed for value "helloworld" (type string) at path "myInt"'
      + expected - actual
      -Cast to Int32 failed for value "helloworld" (type string) at path "myInt" because of "SyntaxError"
      +Cast to Int32 failed for value "helloworld" (type string) at path "myInt"
      
      at Context.<anonymous> (test/int32.test.js:322:16)
      at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

  4) Int32
       cast errors
         when a non-integer decimal string is provided to an Int32 field
           throws a CastError upon validation:
      AssertionError [ERR_ASSERTION]: 'Cast to Int32 failed for value "1.2" (type string) at path "myInt" because of "SyntaxError"' == 'Cast to Int32 failed for value "1.2" (type string) at path "myInt"'
      + expected - actual
      -Cast to Int32 failed for value "1.2" (type string) at path "myInt" because of "SyntaxError"
      +Cast to Int32 failed for value "1.2" (type string) at path "myInt"
      
      at Context.<anonymous> (test/int32.test.js:340:16)
      at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

  5) Int32
       cast errors
         when NaN is provided to an Int32 field
           throws a CastError upon validation:
      AssertionError [ERR_ASSERTION]: 'Cast to Int32 failed for value "NaN" (type number) at path "myInt" because of "SyntaxError"' == 'Cast to Int32 failed for value "NaN" (type number) at path "myInt"'
      + expected - actual
      -Cast to Int32 failed for value "NaN" (type number) at path "myInt" because of "SyntaxError"
      +Cast to Int32 failed for value "NaN" (type number) at path "myInt"
      
      at Context.<anonymous> (test/int32.test.js:358:16)
      at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

  6) Int32
       cast errors
         when value above INT32_MAX is provided to an Int32 field
           throws a CastError upon validation:
      AssertionError [ERR_ASSERTION]: 'Cast to Int32 failed for value "2147483648" (type number) at path "myInt" because of "SyntaxError"' == 'Cast to Int32 failed for value "2147483648" (type number) at path "myInt"'
      + expected - actual
      -Cast to Int32 failed for value "2147483648" (type number) at path "myInt" because of "SyntaxError"
      +Cast to Int32 failed for value "2147483648" (type number) at path "myInt"
      
      at Context.<anonymous> (test/int32.test.js:376:16)
      at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

  7) Int32
       cast errors
         when value below INT32_MIN is provided to an Int32 field
           throws a CastError upon validation:
      AssertionError [ERR_ASSERTION]: 'Cast to Int32 failed for value "-2147483649" (type number) at path "myInt" because of "SyntaxError"' == 'Cast to Int32 failed for value "-2147483649" (type number) at path "myInt"'
      + expected - actual
      -Cast to Int32 failed for value "-2147483649" (type number) at path "myInt" because of "SyntaxError"
      +Cast to Int32 failed for value "-2147483649" (type number) at path "myInt"
      
      at Context.<anonymous> (test/int32.test.js:394:16)
      at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

  8) model: findOneAndUpdate:
       bug fixes
         single nested doc cast errors (gh-3602):
      AssertionError [ERR_ASSERTION]: 'Cast to Number failed for value "not a num" (type string) at path "street" because of "SyntaxError"' == 'Cast to Number failed for value "not a num" (type string) at path "street"'
      + expected - actual
      -Cast to Number failed for value "not a num" (type string) at path "street" because of "SyntaxError"
      +Cast to Number failed for value "not a num" (type string) at path "street"
      
      at Context.<anonymous> (test/model.findOneAndUpdate.test.js:1357:14)
      at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

  9) validation docs
       Cast Errors:
      AssertionError [ERR_ASSERTION]: 'Cast to Number failed for value "not a number" (type string) at path "numWheels" because of "SyntaxError"' == 'Cast to Number failed for value "not a number" (type string) at path "numWheels"'
      + expected - actual
      -Cast to Number failed for value "not a number" (type string) at path "numWheels" because of "SyntaxError"
      +Cast to Number failed for value "not a number" (type string) at path "numWheels"
      
      at Context.<anonymous> (test/docs/validation.test.js:384:12)
      at process.processImmediate (node:internal/timers:485:21)

lib/schema/union.js

…d out of schema, clean up some more inconsistencies

vkarpov15 · 2025-11-03T21:47:09Z

@hasezoey can you please take another look? I did a bunch more refactor to make the constructor signatures more consistent - I was able to make it so that all schema types take in a parentSchema param, although there's still some inconsistencies in function signatures that I would like to fix in the 9.0 branch.

Copilot

Pull Request Overview

Copilot reviewed 24 out of 24 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

lib/types/map.js:5

Unused variable assert.

const assert = require('assert');

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Copilot · 2025-11-03T21:49:14Z

lib/types/map.js


 const Mixed = require('../schema/mixed');
 const MongooseError = require('../error/mongooseError');
+const assert = require('assert');


The assert module is imported but never used in this file. This import should be removed to keep dependencies clean.

Suggested change

const assert = require('assert');

Copilot · 2025-11-03T21:49:14Z

lib/schema/map.js

    this.$isSchemaMap = true;
+
+    // Create the nested schema type for the map values
+    this._createNestedSchemaType(parentSchema, key, options, _schemaOptions);


If parentSchema is null or undefined, calling _createNestedSchemaType will result in a runtime error when it tries to access schema.options.typeKey (line 136) and schema.interpretAsType (line 158). Add a null check or ensure parentSchema is always provided.

Suggested change

this._createNestedSchemaType(parentSchema, key, options, _schemaOptions);

if (parentSchema != null) {

this._createNestedSchemaType(parentSchema, key, options, _schemaOptions);

}

Copilot · 2025-11-03T21:49:15Z

lib/schema/union.js

      throw new Error('Union schema type requires an array of types');
    }
-    this.schemaTypes = options.of.map(obj => options.parentSchema.interpretAsType(key, obj, schemaOptions));
+    this.schemaTypes = options.of.map(obj => parentSchema.interpretAsType(key, obj, schemaOptions));


If parentSchema is null or undefined, this will throw a runtime error. Consider adding validation to ensure parentSchema is provided, or add a guard clause in the constructor.

hasezoey

LGTM, aside from lint and a few nitpicks that are not directly related to this PR.

hasezoey · 2025-11-04T10:57:28Z

lib/schema/documentArrayElement.js

 *
 * @param {String} path
 * @param {Object} options
+ * @param {Object} _schemaOptions


Suggested change

* @param {Object} _schemaOptions

* @param {Object} schemaOptions

The other schematypes dont refer to it with underscore in the jsdoc when unused (re SchemaBoolean, SchemaBuffer, etc)

hasezoey · 2025-11-04T10:58:15Z

lib/schema/map.js

+  constructor(key, options, _schemaOptions, parentSchema) {
+    super(key, options, 'Map', parentSchema);
    this.$isSchemaMap = true;
+


Suggested change

hasezoey · 2025-11-04T10:59:57Z

lib/schema/map.js

 /*!
 * ignore
 */


SchemaMap is public right? This should likely also have a proper jsdoc then like the other schema types (though not directly related to this PR)

hasezoey · 2025-11-04T11:01:41Z

lib/schema/map.js

 class SchemaMap extends SchemaType {
-  constructor(key, options) {
-    super(key, options, 'Map');
+  constructor(key, options, _schemaOptions, parentSchema) {


Suggested change

constructor(key, options, _schemaOptions, parentSchema) {

constructor(key, options, schemaOptions, parentSchema) {

Its not unused

hasezoey · 2025-11-04T11:01:54Z

lib/schema/map.js

    this.$isSchemaMap = true;
+
+    // Create the nested schema type for the map values
+    this._createNestedSchemaType(parentSchema, key, options, _schemaOptions);


Suggested change

this._createNestedSchemaType(parentSchema, key, options, _schemaOptions);

this._createNestedSchemaType(parentSchema, key, options, schemaOptions);

Re: its not unused

refactor: pass parent schema to SchemaType constructors in interpretA…

41bcccf

…sType to make implementing custom container types easier

vkarpov15 added this to the 8.20 milestone Oct 27, 2025

vkarpov15 requested review from AbdelrahmanHafez, Copilot and hasezoey October 27, 2025 18:34

Copilot AI reviewed Oct 27, 2025

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lib/schema/union.js Show resolved Hide resolved

hasezoey approved these changes Oct 28, 2025

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vkarpov15 changed the base branch from master to 8.20 November 1, 2025 20:41

vkarpov15 added 2 commits November 3, 2025 16:12

refactor: handle passing parentSchema correctly to all schema types

d7d2789

refactor: move map embedded schematype instantiation to schema/map an…

1586fc6

…d out of schema, clean up some more inconsistencies

vkarpov15 requested review from Copilot and hasezoey November 3, 2025 21:46

Copilot AI reviewed Nov 3, 2025

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hasezoey approved these changes Nov 4, 2025

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vkarpov15 mentioned this pull request Nov 4, 2025

fix(schema): avoid throwing error on array of unions #15720

Merged

	* @param {Object} _schemaOptions
	* @param {Object} schemaOptions

	constructor(key, options, _schemaOptions, parentSchema) {
	constructor(key, options, schemaOptions, parentSchema) {

	this._createNestedSchemaType(parentSchema, key, options, _schemaOptions);
	this._createNestedSchemaType(parentSchema, key, options, schemaOptions);

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refactor: pass parent schema to SchemaType constructors in interpretAsType to make implementing custom container types easier #15700

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refactor: pass parent schema to SchemaType constructors in interpretAsType to make implementing custom container types easier #15700

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vkarpov15 commented Oct 27, 2025

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