Bundler and linter fail when discriminator value is component name #1877

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1. tobiaspatton-s4

   added

   Type: BugSomething isn't workingSomething isn't working

   on Feb 1, 2025
2. jeremyfiel commented on Feb 1, 2025

   

   jeremyfiel

   on Feb 1, 2025

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   related to #1602

   This particular comment has a good breakdown of each type of reference.
   #1602 (comment)

   The bug described here is directly related to this.

   Explicit Mapping - Value:
   If the mapping section is provided and the value DOES NOT being with ./ then it will be inferred as a name for a schema found under the Component section of the spec

   From the updated 3.1.1 spec.

   The mapping entry maps a specific property value to either a different schema component name, or to a schema identified by a URI. When using implicit or explicit schema component names, inline oneOf or anyOf subschemas are not considered. The behavior of a mapping value that is both a valid schema name and a valid relative URI reference is implementation-defined, but it is RECOMMENDED that it be treated as a schema name.

   Here the discriminating value of dog will map to the schema #/components/schemas/Dog, rather than the default (implicit) value of #/components/schemas/dog. If the discriminating value does not match an implicit or explicit mapping, no schema can be determined and validation SHOULD fail.

   components:
     schemas:
       Pet:
         type: object
         required:
           - petType
         properties:
           petType:
             type: string
         discriminator:
           propertyName: petType
           mapping:
             dog: Dog
       Cat:
         allOf:
           - $ref: '#/components/schemas/Pet'
           - type: object
             # all other properties specific to a `Cat`
             properties:
               name:
                 type: string
       Dog:
         allOf:
           - $ref: '#/components/schemas/Pet'
           - type: object
             # all other properties specific to a `Dog`
             properties:
               bark:
                 type: string
       Lizard:
         allOf:
           - $ref: '#/components/schemas/Pet'
           - type: object
             # all other properties specific to a `Lizard`
             properties:
               lovesRocks:
                 type: boolean
3. jeremyfiel commented on Feb 1, 2025

   

   jeremyfiel

   on Feb 1, 2025

   Contributor

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   OK, narrowed this down to the rule no-unresolved-refs which is incorrectly reporting the error.
   

   redocly-cli/packages/core/src/rules/no-unresolved-refs.ts

   Lines 15 to 19 in fa280a3

   	DiscriminatorMapping(mapping, { report, resolve, location }) {
   	for (const mappingName of Object.keys(mapping)) {
   	const resolved = resolve({ $ref: mapping[mappingName] });
   	if (resolved.node !== undefined) return;

   The discriminator mapping itself is working correctly, this can be verified by this example

   openapi: 3.1.0
   info:
     title: pets
     version: 1.0.0
     license:
       name: Apache 2.0
       identifier: Apache-2.0
   
   servers:
     - url: http://not.real.com/pets.yaml
   
   paths:
     /get-pets:
       get:
         description: get pets
         summary: get pets
         operationId: get_pets
         responses:
           200:
             description: ok
             content:
               application/json:
                 schema:
                   $ref: "#/components/schemas/Animals"
                 examples: 
                   valid_test: 
                     value: 
                       elements:
                         - species: dog
                           rating: 1
                   invalid_test: 
                     value: 
                       elements:
                         - species: dog
                           rating: true
           400:
             description: not ok
   
   components:
     schemas:
       Animals:
         type: object
         properties:
           elements:
             type: array
             items:
               oneOf:
                 - $ref: "#/components/schemas/Cat"
                 - $ref: "#/components/schemas/Dog"
               discriminator:
                 propertyName: species
                 mapping:
                   dog: Dog
                   cat: Cat
   
       Dog:
         type: object
         required:
           - species
         properties:
           species:
             const: dog
           rating:
             type: number
   
       Cat:
         type: object
         required:
           - species
         properties:
           species:
             const: cat
           tuxedo:
             type: boolean
   
     securitySchemes:
       Bearer:
         type: http
         scheme: bearer
         description: JWT auth0 token (without the word 'Bearer')
         bearerFormat: JWT
   
   security:
     - Bearer: []

   The expected error is from the invalid_test example.

   Example value must conform to the schema: `rating` property type must be number.
4. jeremyfiel commented on Feb 1, 2025

   

   jeremyfiel

   on Feb 1, 2025

   Contributor

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   played with a few changes but nothing fixed just yet. Seems this is where it's failing to resolve

   redocly-cli/packages/core/src/walk.ts

   Line 143 in fa280a3

   const resolvedRef = resolvedRefMap.get(refId);

   other changes i've made,

   from this:
   

   redocly-cli/packages/core/src/rules/no-unresolved-refs.ts

   Lines 15 to 17 in fa280a3

   	DiscriminatorMapping(mapping, { report, resolve, location }) {
   	for (const mappingName of Object.keys(mapping)) {
   	const resolved = resolve({ $ref: mapping[mappingName] });

   
   to this:

   DiscriminatorMapping(mapping, { report, resolve, location }) {
         for (const mappingName in mapping) {
           const resolved = resolve({ $ref: `${mapping[mappingName]}` });

   added this test to the no-unresolved-refs.test.ts

   it('should not report on discriminator mapping explicit value', async () => {
       const document = parseYamlToDocument(
         outdent`
           openapi: 3.1.0
           info:
             title: pets
             version: 1.0.0
           servers:
             - url: http://not.real.com/pets.yaml
           paths:
             /get-pets:
               get:
                 description: get pets
                 responses:
                   200:
                     description: ok
                     content:
                       application/json:
                         schema:
                           $ref: "#/components/schemas/Animals"
                         examples: 
                           valid_test: 
                             value: 
                               elements:
                                 - species: dog
                                   rating: 1
                           invalid_test: 
                             value: 
                               elements:
                                 - species: dog
                                   rating: true
                   400:
                     description: not ok
           components:
             schemas:
               Animals:
                 type: object
                 properties:
                   elements:
                     type: array
                     items:
                       oneOf:
                         - $ref: "#/components/schemas/Cat"
                         - $ref: "#/components/schemas/Dog"
                       discriminator:
                         propertyName: species
                         mapping:
                           dog: Dog
                           cat: Cat
               Dog:
                 type: object
                 required:
                   - species
                 properties:
                   species:
                     const: dog
                   rating:
                     type: number
               Cat:
                 type: object
                 required:
                   - species
                 properties:
                   species:
                     const: cat
                   tuxedo:
                     type: boolean
   
         `,
         path.join(__dirname, 'foobar.yaml')
       );
   
       const results = await lintDocument({
         externalRefResolver: new BaseResolver(),
         document,
         config: await makeConfig({
           rules: {
             'no-unresolved-refs': 'error',
           },
         }),
       });
   
       expect(replaceSourceWithRef(results, __dirname)).toMatchInlineSnapshot(``);
     });
5. jeremyfiel commented on Feb 1, 2025

   

   jeremyfiel

   on Feb 1, 2025

   Last edited by jeremyfiel

   Contributor

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   redocly-cli/packages/core/src/ref-utils.ts

   Lines 77 to 86 in fa280a3

   	export function isMappingRef(mapping: string) {
   	// TODO: proper detection of mapping refs
   	return (
   	mapping.startsWith('#') ||
   	mapping.startsWith('https://') ||
   	mapping.startsWith('http://') ||
   	mapping.startsWith('./') ||
   	mapping.startsWith('../') ||
   	mapping.indexOf('/') > -1
   	);

   This is tangentially related and could be another method to resolve these mapping refs rather than the resolvedRefMap method.
6. tatomyr commented on Feb 3, 2025

   

   tatomyr

   on Feb 3, 2025

   Collaborator

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   Looks like a bug indeed. Until it's fixed, you can try working around it with a custom decorator to prepend the schema names in DiscriminatorMapping with #/components/schemas/ or something similar.

   👍React with 👍1Reacted by Tobias Patton
7. tatomyr

   added

   p3

   on Feb 3, 2025
8. tatomyr

   added

   good first issueGood for newcomersGood for newcomers

   $refIncorrect behaviour when resolving references.Incorrect behaviour when resolving references.

   and removed

   good first issueGood for newcomersGood for newcomers

   on Oct 8, 2025