invalid components error when response schema contains additionalProperties

[anjaliSeven]

Given a specification with additional properties in the response schema,
returns error "invalid components: schema "schema1": extra sibling fields: [has schema]"

example:

openapi: 3.0.0
info:
  title: "Service"
  version: 0.1.9
paths:
  /service:
    get:
      responses:
        "200":
          $ref: "#/components/responses/response1"

components:
  responses:
    response1:
      description: response data
      content:
        application/json:
          schema:
            $ref: "#/components/schemas/schema1"

  schemas:
    schema1:
      properties:
        "":
          type: object
          additionalProperties:
            type: string
      type: object
      
    

[fenollp]

# issue772.yml
openapi: 3.0.0
info:
  title: "Service"
  version: 0.1.9
paths:
  /service:
    get:
      responses:
        "200":
          $ref: "#/components/responses/response1"

components:
  responses:
    response1:
      description: response data
      content:
        application/json:
          schema:
            $ref: "#/components/schemas/schema1"

  schemas:
    schema1:
      properties:
        "":
          type: object
          additionalProperties:
            type: string
      type: object

go run github.com/getkin/kin-openapi/cmd/validate@latest issue772.yml
# go: downloading github.com/getkin/kin-openapi v0.114.0
# ...

No issue.

[anjaliSeven]

Hi @fenollp as in v0.113.0 AdditionalProperties has been added with the additional field so the validation is failing for me after the marshalling. It would be very helpful if u can help in marshalling it properly.

func Test(t *testing.T) {
	before, err := os.ReadFile("issue772.yml")
	assert.NoError(t, err)

	loader := openapi3.NewLoader()
	loader.IsExternalRefsAllowed = true
	spec, err := loader.LoadFromData(before)
	assert.NoError(t, err)

	after, err := yaml.Marshal(spec)
	assert.NoError(t, err)
	f, err := os.Create("after.yml")
	assert.NoError(t, err)
	f.WriteString(string(after))

	doc, err := loader.LoadFromFile("after.yml")
	assert.NoError(t, err)
	err = doc.Validate(context.Background())
        t.Log("error from validation", err)
	assert.NoError(t, err)
}

--- FAIL: Test (0.00s)
error from validation invalid components: schema "schema1": extra sibling fields: [has schema]
 Error:      	Received unexpected error:
        	            	invalid components: schema "schema1": extra sibling fields: [has schema]

[fenollp]

1. I have no idea what yaml package you're using
2. Print the problematic YAML file (the after), we should find your issue much faster.

[anjaliSeven]

package used:

	"gopkg.in/yaml.v3"

	"github.com/getkin/kin-openapi/openapi3"
	"github.com/stretchr/testify/assert"
#after.yml
openapi: 3.0.0
components:
    schemas:
        schema1:
            type: object
            properties:
                "":
                    type: object
                    additionalProperties:
                        has: null
                        schema:
                            type: string
    responses:
        response1:
            description: response data
            content:
                application/json:
                    schema:
                        $ref: '#/components/schemas/schema1'
info:
    title: Service
    version: 0.1.9
paths:
    /service:
        get:
            responses:
                "200":
                    $ref: '#/components/responses/response1'

[anjaliSeven]

additionalProperties:
            type: string

when converted to struct and then marshalled is changed to

additionalProperties:
                       has: null
                       schema:
                           type: string
                         

[praneetloke]

I am seeing some weirdness too since v0.113.0 that I think is similar to the issue reported here. Specifically, the changes in #728 seems to be triggering the error. For example, this path:

yaml

paths:
  /owners/{id}:
    get:
      tags:
        - Owners
      summary: Retrieve user or team
      description: >-
        [https://api-docs.render.com/reference/get-owner](https://api-docs.render.com/reference/get-owner)
      parameters:
        - name: Accept
          in: header
          schema:
            type: string
          example: application/json
        - name: id
          in: path
          schema:
            type: string
          required: true
          description: (Required) The ID of the user or team
          example: Lorem amet sin
      responses:
        "200":
          description: OK
          headers:
            Content-Type:
              schema:
                type: string
                example: application/json
          content:
            application/json:
              schema:
                type: object
                $ref: "#/components/schemas/owner"
              example:
                id: nisi aute veniam elit
                name: labore
                email: id adipisicing Excepteur
                type: user
components:
  schemas:
    owner:
      title: "Owner"
      description: "The owner object represents an authorized user or team. The `type` property indicates if the owner is a user or team."
      type: object
      properties:
        id:
          description: The owner ID.
          readOnly: true
          type: string
        name:
          description: The name of the owner.
          type: string
        email:
          description: The email of the owner.
          type: string
        type:
          description: The type of the authorized user.
          type: string
          enum: ["user", "team"]

...fails validation with the error:

invalid paths: invalid path /owners/{id}: invalid operation GET: extra sibling fields: [type]

And when that doc is parsed, the SchemaRef for #/components/schemas/owner looks like this:

I am not sure how the extra slice is being populated on doc parse since I haven't done a deeper investigation into the parsing routine yet. I am also trying to understand the changes in #728.

[fenollp]

Hi, sorry I haven't got much time to look into this right now.
I believe you are right, the issue comes from YAML serialization. The issue should be around this code:

kin-openapi/openapi3/schema.go

Lines 176 to 193 in cb687bf

	type AdditionalProperties struct {
	Has *bool
	Schema *SchemaRef
	}
	// MarshalJSON returns the JSON encoding of AdditionalProperties.
	func (addProps AdditionalProperties) MarshalJSON() ([]byte, error) {
	if x := addProps.Has; x != nil {
	if *x {
	return []byte("true"), nil
	}
	return []byte("false"), nil
	}
	if x := addProps.Schema; x != nil {
	return json.Marshal(x)
	}
	return nil, nil
	}

A couple leads: json+yaml tags may need to be added to the struct. But I believe a better choice is to implement a MarshalYAML func.

@anjaliSeven You should be able to resolve your issue by replacing the YAML package you're using with github.com/invopop/yaml

@praneetloke Take a look around

kin-openapi/refs.sh

Line 81 in e53fe38

x.extra = append(x.extra, key)

[praneetloke]

@fenollp thanks for the tip! It turned out that my API spec was actually incorrect. The type property is unnecessary when a ref is provided. There were other issues as well such as the example property appearing as a child of schema rather than a sibling. So it looks like "disallow unknown properties" is actually working as intended in my case at least.

[anjaliSeven]

@fenollp thanks for the suggestion , will try it

[anjaliSeven]

using github.com/invopop/yaml for marshalling doesn't provide same result as gopkg.in/yaml.v3 for my usecase.

[fenollp]

doesn't provide same result

Yes that's the point. Show us the diff and be helpful.

[anjaliSeven]

@fenollp when marshalled with Invopop, one of the fields returns null. I haven't investigated the reason yet, so I haven't shared any examples. I will share them once I complete my investigation.

[fenollp]

@anjaliSeven Heya, okay. Please reopen this once you do :)