Undefined properties of requests are converted to 0 in the callback of createService

[qiuzhong]

Let's say the client sends an ill-formatted request {a:1} for the service example_interfaces/srv/AddTwoInts (which requires two properties in the request), in the callback of
createService:

  node.createService('example_interfaces/srv/AddTwoInts', 'add_two_ints', (request, response) => {
    console.log(`Incoming request: ${typeof request}`, request);
    let result = response.template;
    result.sum = request.a + request.b;
    console.log(`Sending response: ${typeof result}`, result, '\n--');
    response.send(result);
  });

We get this output:

Incoming request: object { a: 69, b: 0 }
Sending response: object { sum: 69 } 
--

Undefined property request.b is converted to 0 and doesn't throw an Error. If you print the type of request.b, it's number.

[qiuzhong]

@kenny-y , @minggangw , what do you think?

[minggangw]

Sorry for the late response, when we create a JavaScript object in rclnodejs, and a c struct memory will be allocated simultaneously, which is done by ref. So, I think why you get b == 0 is that the ref sets default value for the members of the struct, even though there is no corresponding property in JavaScript object.

[qiuzhong]

So is this the well-defined behavior for rclnodejs? If so, I don't think it's a robust service to accept ill-formatted requests.

[kenny-y]

I think this and #241 can fall into the same category -- strict structure/type checking before using the object