Respond from controller method without express response-CodePudding

I'm trying to respond in case a fetch for an item doesn't return something from another method that doesn't have the express response. I call this method from another that if it has the express response:

const updateItem = async (req, res = response ) => {

    const id = req.params.id;
    const idItem = req.params.idItem; 

    await itemExists( id, idItem);

...

And in the itemExists() function I search for the item in mongo and if it doesn't exist I want to send it as a response but I don't know how to do it without using Express response:

const itemExists = async ( id, idItem ) => {

    const item = await PettyCashItems.findOne({ _id: id, "items._id": idItem });

    if (!item) {
        return ......
    }
}

Thanks.

CodePudding user response：

As already mentioned by one of the comments, there's no way to use response object without having access to it.

However, what you want can be achieved in two ways:

1- Easy way - return a value from itemExists function and send the response according to returned value from itemExists

const updateItem = async (req, res = response ) => {

    const id = req.params.id;
    const idItem = req.params.idItem; 

    const exists = await itemExists( id, idItem);

    if (exists) {
      res.send('YES')
      return;
    }

    res.send('NO');
}

2- Better way - Setup error handling for your express application so all thrown error are caught and response is sent based on the thrown error, then you can simply

class BaseHTTPException extends Error {
  constructor(statusCode) {
    super();
    this.statusCode = statusCode;
  }

}


class ItemDoesNotExistException extends BaseHTTPException {
  constructor() {
    super(400)
  }
}

throw new ItemDoesNotExistException()

in your itemExists function.

Further reading: https://expressjs.com/en/guide/error-handling.html