[typescript] allOf with multiple values is not handled properly

[Fredx87]

Description

If a schema is defined with the allOf operator with multiple values, the generated model is an interface that extends only the first value.

openapi-generator version

3.2.2

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: TestApi
  version: 1.0.0
paths:
  /test:
    get:
      summary: Test
      operationId: testApi
      responses:
        "200":
          description: Ok
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/ModelC"
components:
  schemas:
    ModelA:
      properties:
        foo:
          type: string
    ModelB:
      properties:
        bar:
          type: string
    ModelC:
      allOf:
        - $ref: "#/components/schemas/ModelA"
        - $ref: "#/components/schemas/ModelB"
        - type: object
          properties:
            baz:
              type: string

Command line used for generation

docker run --rm -v ${PWD}:/local openapitools/openapi-generator-cli:v3.2.2 generate -i /local/swagger.yaml -g typescript-angular -o /local/ts-angular -DngVersion=6.0
docker run --rm -v ${PWD}:/local openapitools/openapi-generator-cli:v3.2.2 generate -i /local/swagger.yaml -g typescript-fetch -o /local/ts-fetch

Suggest a fix/enhancement

The model generated for ModelC is the following interface:

export interface ModelC extends ModelA { 
    baz?: string;
}

When it should be:

export interface ModelC extends ModelA, ModelB { 
    baz?: string;
}

[macjohnny]

I guess this is due to the fact that we are using interfaces here, which can extend multiple interfaces (see https://www.typescriptlang.org/docs/handbook/interfaces.html#extending-interfaces) as opposed to classes. So this could be implemented. @Fredx87 would you like to give it a try and support @TiFu in his typescript-refactoring #802

[mwoodland]

I've just run into this same issue with the Spring generator, except in that case it's generating classes so multiple inheritance wouldn't work.

[macjohnny]

@jmini @wing328 do you think this is a general bug? If the target language does not allow extending multiple classes, then the generated model should copy all properties.

[mwoodland]

@macjohnny for java at least the model could be implementing multiple interfaces instead of extending a concrete class but I'm guessing that's a fairly big change to the generator.

[Shockolate]

Another option for Typescript is the use of intersection types.

openapi: 3.0.0
info:
  title: TestApi
  version: 1.0.0
paths:
  /test:
    get:
      summary: Test
      operationId: testApi
      responses:
        "200":
          description: Ok
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/ModelC"
components:
  schemas:
    ModelA:
      properties:
        foo:
          type: string
    ModelB:
      properties:
        bar:
          type: string
    ModelC:
      allOf:
        - $ref: "#/components/schemas/ModelA"
        - $ref: "#/components/schemas/ModelB"
        - type: object
          properties:
            baz:
              type: string

type ModelC = ModelA & ModelB & {
  baz?: string
}

[wing328]

Hi folks, I've filed #1360 with better inheritance/composition support. Please give it a try and let us know if you've any feedback for us.

[topce]

hi @wing328 I checked against master from today and it is even worst
generated code

import { ModelA } from './modelA';
import { ModelB } from './modelB';


export interface ModelC { 
    baz?: string;
}

and it should be

import { ModelA } from './modelA';
import { ModelB } from './modelB';


export interface ModelC extends ModelA, ModelB { 
    baz?: string;
}

so it look like it is broken now
Few days ago it was working (at least for one interface inheritance)
so it is some recent PR that broke it

[wing328]

@topce let me look into it...