Include shared schemas in response

[PatrickHeneise]

I use a shared schema:

{
  "$id": "https://foo/common.json",
  "type": "object",
  "definitions": {
    "foo": {
      "$id": "#bar",
      "type": "object",
      "properties": {
        "id": { "type": "string" }
      }
    }
  }
}

And trying to use that schema in the response validation:

It works perfectly fine in a list/index route:

200: {
  type: 'array',
  items: {
    $ref: 'https://foo/common.json#bar'
  }
}

but not for get /:id

response: {
  200: 'https://foo/common.json#bar'
}

I'm trying to track down the issue but would appreciate a hint to where to start. Everything works fine if I add the schema "bar" individually before:

  fastify.addSchema({
    $id: 'bar',
    type: 'object',
    properties: {
      id: { type: 'number' }
    }
  })

...

works: 200: 'bar#'

[mcollina]

What does it mean “it works”? @Eomm is the master of shared schemas, he might take a look here as well.

[PatrickHeneise]

Using "bar#" (which is not a common/shared schema) works. Shared schema doesn't.

[Eomm]

This should work (with last fast-json-stringify installed):

response: {
  200: {$ref: 'https://foo/common.json#bar'}
}

When you write someId# (hash at the end) you are using the "replace way" of the shared schema feature, but if you write the $ref as you did, you are using the $ref-way so you need to use the standard schema definition.

[PatrickHeneise]

I thought I tested that case and it didn't work, but I'll try again in the morning.

[PatrickHeneise]

response: {
  200: { $ref: 'https://foo/common.js#bar' }
}

UnhandledPromiseRejectionWarning: TypeError: Cannot read property '$ref' of undefined

[Eomm]

Looking here:

fastify-swagger/dynamic.js

Line 96 in c41d37c

const schema = transform

Maybe, the shared schemas are not provided to swagger.

I can't go deeper now, could you check it?

[PatrickHeneise]

when using 'bar#', the schema is transformed to an object, with the ref it's not.

I've decided to move forward with multiple schema files instead of common.json.

[PatrickHeneise]

Going back and forth experimenting with the schemas. I found some inconsistencies:

works:

body: { $ref: '/foo.json#/definitions/bar' }

fails:

response: {
  200: { $ref: '/foo.json#/definitions/bar' }
}

TypeError: Cannot read property '$ref' of undefined in fast-json-stringify/index.js:485:15

Then I tried

response: {
  200: '/foo.json#/definitions/bar'
}

Error: schema is invalid: data should be object,boolean in fast-json-stringify/index.js:30:17

[Eomm]

Yeah, that doesn't surprise me:

• body/querystring etc => use ajv as parser
• response => use fast-json-stringy as serializer

For the trouble:

• 200: { $ref: '/foo.json#/definitions/bar' } => I think this should work, could you share your npm ls?
• 200: '/foo.json#/definitions/bar' => it is correct that it throw error since it is not valid

[PatrickHeneise]

It's a long list ... I selected the path that might be the one you're looking for:

├─┬ [email protected]
│ ├── [email protected] deduped
│ ├── UNMET DEPENDENCY ajv-merge-patch@^4.1.0
│ ├─┬ [email protected]
│ │ ├── [email protected] deduped

started the project from scratch, so the dependencies should all be up-to-date.

If you point me into the direction, I'm happy to help fix this, as I need it in my current project.

[Eomm]

Sorry @PatrickHeneise , I missed your comment. Did you solve meanwhile?

Otherwise, I will check this problem in next days

[PatrickHeneise]

No, I worked around the issue by placing the schema I need in /index.js and reference from there, but it's not pretty.

[vladlen-volkov]

I've almost the same problem. The swagger doesn't recognize some shared schemas.
Here is a repo with reproducing of error.

There are 4 routes:
GET /api/auth -> works fine, 'cause I wrap my shared schema in additional property "userSource"
GET /api/chats/ -> is ok with shared schema

GET /api/auth-broken -> fails in UI with Could not resolve reference: undefined undefined
PUT ​/api​/chats​/{chatId}​/messages -> fails in UI like a previous [despite of wrapping]

Are there any ways to avoid this? Or should we waiting for fixing?

[dannysofftie]

Came across the same issue today.

This works, when the response is of type array

response: {
 200: {
    description: 'Successful response',
    type: 'array',
      items: {
        $ref: '#Journal',
       },
   },
},

But this doesn't work when response is an object. I don't know if this is the intended behaviour.

response: {
 200: {
    description: 'Successful response',
    type: 'object',
    $ref: '#Journal',
   },
},

As a workaround, I used fastify instance to pull the already compiled schema and it works as expected:
Option 1.

response: {
 200: {
    description: 'Successful response',
    type: 'object',
   ...(fastify.getSchema('#Journal') as object), // silence typescript
   },
},

Option 2.

response: {
 200: fastify.getSchema('#Journal')
},

[pelepelin]

Does anybody here have a full example of referencing the models from dynamic routes the Swagger way?

    "responses": {
      "500": {
        "schema": {
          "$ref": "#/definitions/ErrorModel"
        }
      }
    }

I've tried to put "definitions" into their place in the plugin options, but that did not work. Should it be a separate feature request?

[pelepelin]

So when I did

addSchema({
  $id: 'shared',
  definitions
});

then this response definition does not blow up fastify

500: {
      $ref: 'shared#/definitions/ErrorResponse'
    }

However, in this case the schema is nested and the path is transformed in output: "500":{"schema":{"$ref":"#/definitions/def-0/definitions/ErrorResponse"} which violates Swagger spec as definitions object must not be nested https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#definitionsObject

[melroy89]

Using:

fastify.addSchema({
    $id: 'shared',
    type: 'object',
    definitions: {
      internalServerErrorResponse: {
        type: 'object',
        description: '500 Internal Server Error',
        properties: {
          message: {
            type: 'string',
            description: 'Error message',
            example: 'Some internal error message'
          }
        }
      }
    }
  })

And then use the shared definition:

    500: {
      $ref: 'shared#/definitions/internalServerErrorResponse'
    }

I will get:

[melroy89]

OpenAPI v3 component responses also doesn't work in Fastify Swagger, so I created a ticket for that: #793

[melroy89]

Now I'm using addSchema without definitions, but only a top level ID:

fastify.addSchema({
  $id: 'internalServerErrorResponse',
  type: 'object',       
  description: '500 Internal Server Error',
  properties: {
    message: {
      type: 'string',
      description: 'Error message',
      example: 'Some internal error message'
    }
  }
})

Then use it in your schema like this:

schema: {
  description: 'example',
  response: {
    500: {
      $ref: 'internalServerErrorResponse#'
    }
  }
}

This ALMOST works.. Except the description message still says "Default Response" in Swagger UI: