Generate server: UnmarshalJSON redeclared for object with default values when --strict-additional-properties specified

[mdelvecchio-wasabi]

Problem statement

Using go-swagger to generate a server. My schema defines an object with default values specified for some properties, and I am specifying the --strict-additional-properties command-line option.

The generated code has two instances of the UnmarshalJSON() method for this object, resulting in a compilation error.

If the server is generated without the --strict-additional-properties command-line option, only one UnmarshalJSON() method is generated.

In addition, if the default values are removed from the Swagger definition, only one UnmarshalJSON() method is generated.

Please remove the sections that don't apply

Swagger specification

swagger: '2.0'
info:
  title: Test API
  description: Test
  version: v1
host: host
schemes:
- https
- http
basePath: /path
produces:
- application/json

paths:
  /obj:
    get:
      summary: Get an object
      operationId: getObject
      responses:
        200:
          description: The object
          schema:
            $ref: '#/definitions/MyObject'

definitions:
  MyObject:
    title: My object
    type: object
    properties:
      string1:
        type: string
        title: A string
      bool1:
        type: boolean
        title: A boolean
    default:
      string1: "first"
      bool1:   false

Steps to reproduce

1. Generate the server:

./go-swagger generate server --strict-additional-properties

2. Inspect the resulting models/my_object.go file, and see two definitions for UnmarshalJSON():

func (m *MyObject) UnmarshalJSON(b []byte) error {
	type MyObjectAlias MyObject
	var t MyObjectAlias
	if err := json.Unmarshal([]byte("{\"bool1\":false,\"string1\":\"first\"}"), &t); err != nil {
		return err
	}
	if err := json.Unmarshal(b, &t); err != nil {
		return err
	}
	*m = MyObject(t)
	return nil
}

// UnmarshalJSON unmarshals this object while disallowing additional properties from JSON
func (m *MyObject) UnmarshalJSON(data []byte) error {
	var props struct {

		// A boolean
		Bool1 bool `json:"bool1,omitempty"`

		// A string
		String1 string `json:"string1,omitempty"`
	}

	dec := json.NewDecoder(bytes.NewReader(data))
	dec.DisallowUnknownFields()
	if err := dec.Decode(&props); err != nil {
		return err
	}

	m.Bool1 = props.Bool1

	m.String1 = props.String1

	return nil
}

Environment

swagger version: v0.21.0
go version: go1.11.5
OS: Linux

[fredbi]

Thanks for reporting this. The problem is indeed more general than this specific use case: unmarshallers with default values conflict with other unmarshallers. I am reshuffling the templates for serializers so we can get a clearer view on this.