req.question/req.answer

Hi Eli Levit ,

Good question.

Well, they are assigned/defined at the top of the routes.js file. More precisely here:

router.param('qID', function(req, res, next, id) {
    Question.findById(id, function(err, doc) {
        if (err) return next(err)
        if (!doc) {
            err = new Error('Not Found')
            err.status = 404
            return next(err)
        }
        req.question = doc  // Here is where req.question is defined.
        return next()
    })
})

router.param('aID', function(req, res, next, id) {
    req.answer = req.question.answers.id(id)   // Here is where req.answer is defined
    if (!req.answer) {
        err = new Error('Not Found')
        err.status = 404
        return next(err)
    }
    next()
})

What does that mean? Well:

First of all the question and answer properties are created there and assigned as properties to the request object (so you can use them in different routes without assigning them every single time and all of that, now you can just use them as properties: req.question or req.answer and that's it). Secondly, they're assigned their value depending on other stuff. Let's decompose it a little bit:

/****req.question*************/

• req.question is doc (req.question = doc)...

• ... where doc is the document (in the mongoDB) found when searching by ID. (Question.findById(id, function(err, doc))

• Which ID? The ID of the question document, provided on the first line as an arg. (function(req, res, next, id))

So req.question is the question of the current request.

/********req.answer*************/

• req.answer is, precisely, the answer

• -> within the answers collection (req.answer = req.question.answers.id(id))

• -> within that respective question document (req.answer = req.question.answers.id(id))

• -> that has the id (req.answer = req.question.answers.**id(id)**)

• -> provided in the args (function(req, res, next, **id**))

Hope that clear things a bit, but if still unclear, feel free to follow up here.