API design

nest.js

In nest.js all apis are defined in controllers. Usually the api follows the following syntax:

'/api/v3/resource'

• Each controller is responsible for a specific resource.
• The controller is responsible for the routing and the validation of the request.
• The controller calls a service to handle the request.
• The service is responsible for the business logic.
• The service calls a repository to access the database.
• The repository is responsible for the database access.

Responses

When returning a response like this:

@Controller('cards')
export class CardController {
    @ApiOperation({summary: 'Create a new element on a card.'})
    @ApiExtraModels(
        ExternalToolElementResponse,
        FileElementResponse,
        LinkElementResponse,
        RichTextElementResponse,
        SubmissionContainerElementResponse
    )
    @ApiResponse({
        status: 201,
        schema: {
            oneOf: [
                {$ref: getSchemaPath(ExternalToolElementResponse)},
                {$ref: getSchemaPath(FileElementResponse)},
                {$ref: getSchemaPath(LinkElementResponse)},
                {$ref: getSchemaPath(RichTextElementResponse)},
                {$ref: getSchemaPath(SubmissionContainerElementResponse)},
            ],
        },
    })
    @ApiResponse({status: 400, type: ApiValidationError})
    @ApiResponse({status: 403, type: ForbiddenException})
    @ApiResponse({status: 404, type: NotFoundException})
    @Post(':cardId/elements')
    public async createElement(
		@Param() urlParams: CardUrlParams,
		@Body() bodyParams: CreateContentElementBodyParams,
		@CurrentUser() currentUser: ICurrentUser
	): Promise<AnyContentElementResponse> {
        const {type, toPosition} = bodyParams;
        const element = await this.cardUc.createElement(currentUser.userId, urlParams.cardId, type, toPosition);
        const response = ContentElementResponseFactory.mapToResponse(element);

        return response;
    }
}

We want to use decorators to explain the intent of the response.
The @ApiOperation decorator is used to define the summary.
The @ApiResponse decorator is used to define the response.
The @ApiExtraModels decorator is used to define the response models.

The final response should either be an javascript Object or an array. We do not return primitives like string or boolean.

Swagger will automatically generate the response schema from the response object.