CODEWITHSUNDEEP
javascriptnode.jspromise
jaekie
jaekie

Reputation: 2303

Promise Chain doesn't seem to continue

I'm trying to get my promise chain to work in my express post, but can't seem to figure out why it won't work, even though I've done this before.

I added many logs to follow where it stops, and it seems to stop after the validation resolve, does not continue

Promise:

    router.post('/auth/token', function (req, res) {
      var schema = require('./schema/token.js');

      var data = {
        username: req.body.username,
        password: req.body.password
      };

      new Promise(function (resolve, reject) {
        logger.info(`Validating request..`);
        return validator.validate(schema, data);
      }).then(function () {
        logger.info(`Getting token..`);
        return authentication.getToken(data.username, data.password);
      }).then(function (result) {
        logger.info(`Received token..`);
        res.send(result);
      }).catch(function (err) {
        logger.info(`Unable to receive token..`);
        res.send(err);
      })
  })

Validator.js:

module.exports.validate = function (schema, data) {
    return new Promise(function(resolve, reject){
        logger.info(`Loading schema..`);
        if (!schema) {
            logger.info(`Missing schema, rejecting promise..`);
            return reject(new Error('Missing schema'));
        }

        const ajv = new Ajv({ v5: true, allErrors: true });

        logger.info(`Compling schema..`);
        const validate = ajv.compile(schema);
        logger.info(`Validating schema..`);
        const valid = validate(data);

        if (!valid) {
            const errors = validate.errors.map((error) => `${error.dataPath.replace('.', '')}: ${error.message}`);
            const err = new Error(errors);
            return reject(err);
        }

        logger.info(`Valid schema.. resolving..`);
        return resolve();
    })
}

When I run this.. the logs say the following:

info: Validating request..
info: Loading schema..
info: Compling schema..
info: Validating schema..
info: Valid schema.. resolving..

No longer continues, it should continue to the next promise, now if I change the first promise and force a resolve and reject, it'll work but as far as I know, that should not be required as the validate returns a promise and I'm not getting any errors

Any ideas?

Upvotes: 1

Views: 142

Answers (1)

T.J. Crowder
T.J. Crowder

Reputation: 1074365

Don't create a new promise, use the one from validate; see *** below:

router.post('/auth/token', function (req, res) {
    var schema = require('./schema/token.js');

    var data = {
      username: req.body.username,
      password: req.body.password
    };

    logger.info(`Validating request..`);      // ***
    validator.validate(schema, data)          // ***
    .then(function () {
      logger.info(`Getting token..`);
      return authentication.getToken(data.username, data.password);
    }).then(function (result) {
      logger.info(`Received token..`);
      res.send(result);
    }).catch(function (err) {
      logger.info(`Unable to receive token..`);
      res.send(err);
    })
})

The issue is you never resolve the new promise you create. But since there's no good reason to create a new promise when you already have one, the solution is to use the one you have.

Upvotes: 1

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