"Resolve error" when definition url is relative AND the definition contains self-referencing schema

[domaindrivendev]

Q&A (please complete the following information)

• OS: Windows 10
• Browser: Chrome
• Version: 80.0.3987.149
• Method of installation: npm
• Swagger-UI version: 3.25.0
• Swagger/OpenAPI version: OpenAPI 3.0

Content & configuration

Example Swagger/OpenAPI definition:

NOTE: The Product schema's self-referencing property. Without this the error doesn't occur.

openapi: 3.0.1
info:
  title: Test API
  version: v1
paths:
  /products:
    post:
      tags:
        - Products
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Product'
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                type: integer
                format: int32
components:
  schemas:
    Product:
      type: object
      properties:
        id:
          type: integer
          format: int32
          readOnly: true
        description:
          type: string
          nullable: true
        parentProduct:
          $ref: '#/components/schemas/Product'

Swagger-UI configuration options:

NOTE: The relative url. If this is absolute or root-relative, the error doesn't occur.

      const ui = SwaggerUIBundle({
        url: "v1/swagger.json",
        dom_id: '#swagger-ui',
        deepLinking: true,
        presets: [
          SwaggerUIBundle.presets.apis,
          SwaggerUIStandalonePreset
        ],
        plugins: [
          SwaggerUIBundle.plugins.DownloadUrl
        ],
        layout: "StandaloneLayout"
      })

Describe the bug you're encountering

The UI displays an error (see screenshot) with the Swagger/OpenAPI definition and UI configuration shown above. I'm pretty certain it's the combination of self-referencing schema's and a "page-relative" url in the swagger-ui config that's producing this issue.

To reproduce...

Steps to reproduce the behavior:

1. With the above definition and ui config, navigate to the UI
2. Try to expand the Product schema in the "Schemas" section at the bottom of the UI
3. See error

Expected behavior

No error and the schema is expanded correctly

Screenshots

Additional context or thoughts

This is particularly problematic for cases where the Swagger/OpenAPI definition and UI are hosted together (e.g. Swashbuckle), and in a reverse-proxy / virtual directory environment.

[domaindrivendev]

@webron wondering if you have any insights into this issue? It seems pointing the UI to a relative definition url is broken if the definition contains self-referencing/cyclical schemas. I would expect this to be a fairly common scenario.

[webron]

@domaindrivendev Cyclic references pose a set of challenges to deal with. While some cases may be covered, we keep discovering cases that are not.

[yurkom]

It is still reproducible
Swagger-UI version: 3.36.2
Browser: Any (FF, Chrome, Edge)
Method installation: webjars.org

URL to Swagger UI: http://localhost:8080/dynamicpath/api-docs/index.html?url=../openapi.json
URL to OpenAPI v3 schema: http://localhost:8080/dynamicpath/openapi.json

Note: this issue is not reproducible on Swagger UI: v3.31.1

[Olard]

It is still reproducible

Swagger-UI version: 4.15.0
Browser: Firefox
Dependency
org.webjars
swagger-ui
4.15.0