Convenient errors

If spec meets all following requirements:

• Every operation defines the same default response
• This response defines only one application/json media

then ogen generates special handler for errors returned by Handler implementation and does not generate default response variant.

For example:

openapi: 3.0.3
info:
  title: Convenient errors example
  version: 0.1.0
paths:
  /me:
    get:
      responses:
        "200":
          description: User
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/User"
        default:
          description: General Error
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Error"
  /users:
    post:
      requestBody:
        description: User to create
        required: true
        content:
          application/json:
            schema:
              $ref: "#/components/schemas/User"
      responses:
        "201":
          description: OK
        default:
          description: General Error
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Error"
components:
  schemas:
    User:
      type: object
      required:
        - id
      properties:
        id:
          type: integer
    Error:
      description: Represents error object
      type: object
      properties:
        code:
          type: integer
          format: int64
        message:
          type: string
      required:
        - code
        - message

// Handler handles operations described by OpenAPI v3 specification.
type Handler interface {
    ...
    // NewError creates ErrorStatusCode from error returned by handler.
    //
    // Used for common default response.
    NewError(ctx context.Context, err error) ErrorStatusCode
}

Force or Disable Convenient errors

Use generator.convenient_errors option

generator:
  # `auto` (default) generates `NewError` if possible
  # `on` tells generator to fail if spec does not meet requirements
  # `off` disables `Convenient errors` at all
  convenient_errors: "auto"