[BUG] [C++][Pistache] cpp-pistache-server response 400 when request joson field was missing

Created by: haibinzero

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [] [Optional] Bounty to sponsor the fix (example)

Description

The response for missing manadatory request body is 500 (internal server error), but what we wanted is 400 (bad request)

openapi-generator version

4.0.0-SNAPSHOT

OpenAPI declaration file content or url

swagger: '2.0'

info:
  title: REST API
  version: v1

basePath: /api/hardware/v1

schemes:
  - http

paths:
  /vnf/{vnfId}/vm/{vmId}/interface:
    parameters:
      - in: path
        name: vnfId
        description: VNF instance Id
        required: true
        type: string
      - in: path
        name: vmId
        description: VM instance Id
        required: true
        type: string
    post:
      summary: Create interface instance under specified VM
      description: Create interface
      consumes:
        - application/json
      produces:
        - application/json
      parameters:
        - in: body
          name: interface
          description: json containing interface configuration
          schema:
            $ref: "#/definitions/Interface"
      responses:
        '200':
          description: OK
          schema:
            properties:
              link:
                $ref: "#/definitions/Link"
          examples:
            application/json:
              {
                "link": {
                  "rel": "self",
                  "href": "/vnf/1/vm/1/interface/1"
                }
              }
        '400':
          description: Bad request
        '404':
          description: Not found
        default:
          description: Unexpected error

definitions:
  Link:
    title: HATEOAS link
    properties:
      rel:
        description: relation with the link
        type: string
        example: "self"
      href:
        description: URIs relative to base URI
        type: string
        example: "/vnf/1/vm/100/interface/1"
    required:
      - href

  Interface:
    title: Interface.
    required:
      - ipAddress
      - name
      - type
    properties:
      ipAddress:
        type: string
        example: 169.254.0.4
      name:
        type: string
        enum:
          - eth0
          - eth1
        example: eth0
      type:
        type: string
        enum:
          - physical
          - logical
        example: physical

Command line used for generation

java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate \
-i swagger.yaml \
-g cpp-pistache-server \
-o cpp

Steps to reproduce

[root@kongfu ~]# curl -i -d '{"ipAddress": "192.168.1.1","name": "eth0","type": "logical"}' -H "Content-Type: application/json" -X POST http://localhost:8080/api/hardware/v1/vnf/1/vm/1/interface
HTTP/1.1 200 OK
Connection: Close
Content-Length: 14

Do some magic
[root@kongfu ~]# curl -i -d '{"ipAddress": "192.168.1.1","name": "eth0"}' -H "Content-Type: application/json" -X POST http://localhost:8080/api/hardware/v1/vnf/1/vm/1/interface
HTTP/1.1 500 Internal Server Error
Content-Length: 54

[json.exception.out_of_range.403] key 'type' not found[root@kongfu ~]# curl -i -d '{"ipAddress": "192.168.1.1","name": "eth0"}' -H "Content-Type: application/json" /1/interface://localhost:8080/api/hardware/v1/vnf/1/vm/
HTTP/1.1 500 Internal Server Error
Content-Length: 54

Related issues/PRs

Suggest a fix

Response 400 (Bad request) when the request body missing mandatoy fields.

void DefaultApi::vnf_vnf_id_vm_vm_id_interface_post_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
    // Getting the path params
    auto vnfId = request.param(":vnfId").as<std::string>();
    auto vmId = request.param(":vmId").as<std::string>();
    
    // Getting the body param
    
    Interface interface;
    
    try {
      nlohmann::json::parse(request.body()).get_to(interface);
      this->vnf_vnf_id_vm_vm_id_interface_post(vnfId, vmId, interface, response);
    } catch (std::runtime_error & e) {
      //send a 400 error
      response.send(Pistache::Http::Code::Bad_Request, e.what());
      return;
    }

}

Changes to

void DefaultApi::vnf_vnf_id_vm_vm_id_interface_post_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
    // Getting the path params
    auto vnfId = request.param(":vnfId").as<std::string>();
    auto vmId = request.param(":vmId").as<std::string>();
    
    // Getting the body param
    
    Interface interface;
    
    try {
      nlohmann::json::parse(request.body()).get_to(interface);
    } catch (nlohmann::detail::exception & e) {
      //send a 400 error
      response.send(Pistache::Http::Code::Bad_Request, e.what());
      return;
    }
    // the std::runtime_error was caught outside and responsed 500
    this->vnf_vnf_id_vm_vm_id_interface_post(vnfId, vmId, interface, response);
}