Node/Mongoose - Error: Can't set headers after they are sent

Question

In my Nodejs code for Mongoose, I've got a create function that used to work just fine, but something has happened where when the function is invoked, it fires and the request is made, but I get this error:

Here is the error in my terminal:

PUT /api/request/create 200 98.981 ms - 1929
events.js:160
      throw er; // Unhandled 'error' event
      ^

Error: Can't set headers after they are sent.

Here is my function:

exports.create = (req, res, next) => {
  const body = req.body;

  const Request = new Requests({
    //customer_id: body.customer_id,
    customer: body.customer,
    tasks: body.tasks,
    submitted_by: body.submitted_by,
    assignees: body.assignees,
    // safety_equipment: body.safety_equipment,
    special_instructions: body.special_instructions,
    area_instructions: body.area_instructions,
    additional_equipment: body.additional_equipment,
    access: body.access,
    training: body.training,
    ppe: body.ppe,
    description: body.description,
    square_footage: body.square_footage,
    flooring_type: body.flooring_type,
    due_date: body.due_date,
    is_converted: body.is_converted,
    quote_amount: body.quote_amount,
    is_billable: body.is_billable,
    budgeted_time: body.budgeted_time,
    site_visit: body.site_visit,
    locations: body.locations,
    job_number: body.job_number
  });

  Request.save( (err, request) => {
    if (err) {
      res.status(401).json({
        message: err
      });
      console.log(err);
    }

      res.status(200).json({
        request
      });

      return next();
  });
}

I have other places in my app that utilize almost identical code and they don't have any issue. Is there some kind of race condition that's happening that I'm not accounting for here?

Answer 1

If err is true, then your code will respond with the status 401 and then again trying to respond with status 200. So try

 if (err) {
              res.status(401).json({
                message: err
              });
              console.log(err);
            }
// Add else
  else{

              res.status(200).json({
                request
              });
        }