CODEWITHSUNDEEP
javascriptnode.js
DennisTurn
DennisTurn

Reputation: 139

Express router callbacks

I'm a little new to Express/Node.js/Mongoose and I've ran into callback hell. What I'm trying to do is get a request in to this API URL /page/module/add/:id, if successful call buildMod(data), then that function calls getMod(data), and then that function calls writeMod(data) and eventually I want to pass the true value right back up to my router.

Once I have the response, I want to return it. I've searched online and there's not many similar situations--I personally think I've got myself in too deep...

router.get('/page/module/add/:id', function(req, res) {
    Client.find({"emailAddress": emailAddress, "sequence.slug": pageSlug}, 
{"emailAddress": 1, "sequence.$": 1}, function (err, data) {
        if (!err) {
            res.statusCode = 200;

            buildMod(data);

            return res.json(data);
        } else {
            res.statusCode = 500;

            log.error('Internal error(%d): %s', res.statusCode, err.message);

            return res.json({
                error: 'Server error'
            });
        }
    }).select('sequence emailAddress domain');
});


function buildMod(data) {
    getMod(data);
}

function getMod(data) {
    Module.find({ 'module_id': moduleNumID }, function (err, module) {
        if(!module) {
            return false;
        }

        if (!err) {
            writeMod(data);
        } else {
            return false;
        }
    });

}

function writeMod(data) {
    fs.appendFile(location, content, function(err) {
         if (err) throw err;
         return true;
    });
}

I know the declarations are wrong for the functions for callbacks but I've been trying and I just can't seem to get past this stage. I'm sure this is definitely possible, any help is really appreciated!

Upvotes: 0

Views: 2353

Answers (1)

Rayon
Rayon

Reputation: 36609

fs.appendFile is asynchronous and you can not return from asynchronous calls.

Make use of callback

router.get('/page/module/add/:id', function(req, res) {
  Client.find({
    "emailAddress": emailAddress,
    "sequence.slug": pageSlug
  }, {
    "emailAddress": 1,
    "sequence.$": 1
  }, function(err, data) {
    if (!err) {
      res.statusCode = 200;
      buildMod(data, function(data) {
        res.json(data);
      });
    } else {
      res.statusCode = 500;
      log.error('Internal error(%d): %s', res.statusCode, err.message);
      return res.json({
        error: 'Server error'
      });
    }
  }).select('sequence emailAddress domain');
});


function buildMod(data, cb) {
  getMod(data, cb);
}

function getMod(data, cb) {
  writeMod(data, cb);
}

function writeMod(data, cb) {
  fs.appendFile(location, content, function(err) {
    if (err) throw err;
    cb(true);
  });
}

Upvotes: 3

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