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How to rewrite a number of conditional statements with Q promises in node.js?

exports.create = function(req, res) {
  var company_id = req.company_id;
  var client = new Client(req.body);

  Company.findOne({_id: company_id}, function(err, company) {
    if(err) {
      response = {
        status: 'error',
        error: err
      }

      return res.json(response);
    } else if(!company) {
      response = {
        status: 'error',
        error: 'Invalid company_id'
      }

      return res.json(response);
    } else {
      client.save(function(err) {
        if(err) {
          response = {
            status: 'error',
            error: err
          }
        } else {
          response = {
            status: 'ok',
            client: client
          }
        }

        return res.json(response);
      });
    }
  });
}

What is my code (using Expressif that matters). I am trying to learn more about promises, namely Q. I feel that this is the ideal logic that can be implemented using promises to avoid this hairy conditional socket. But I'm not sure where to start?

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2 answers

But I'm not sure how to start?

Promise. , . , response ( ) / err .

exports.create = function(req, res) {
  var client = new Client(req.body);

  Q.ninvoke(Company, "findOne", {_id: req.company_id}).then(function(company) {
    if(!company)
      throw 'Invalid company_id';
    else
      return company;
  }).then(function(company) {
    return Q.ninvoke(client, "save");
  }).then(function(saveResult) {
    return {
      status: 'ok',
      client: client
    };
  }, function(err) {
    return {
      status: 'error',
      error: err
    };
  }).done(function(response) {
    res.json(response);
  });
};
+2

Promises. Promises - node.js, , , . , .findOne , - , , , , , Promises.

.save. , Promises, :

new Promise(function() {
    Company.findOne()
    ...
.then(function(company) {
    company.update()
    ...
}, function(err) {
    ...
})

, .

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