CODEWITHSUNDEEP
javascriptnode.jsasynchronous
jhamm
jhamm

Reputation: 25062

My callbacks are wrong - I am returning my response to my error object - Nodejs

I am trying to learn node and understand how callbacks are working. I am doing this by trying to use the async lib. I am trying to hit my db with 2 separate calls and use the async lib to let me know when my object is ready to build. Here is my aysnc code:

  async.parallel({
    one: function(callback) {
      getUser(id, callback);
    },
    two: function(callback) {
      getUserServices(id, callback);
    }
  }, function(err, results) {
    if(err) {
      console.log(err);
      new Error();
    }
    res.json(result);
  });

Here are what my functions look like where I am calling the db. There are both basically the same function:

var getUser = function(id, callback) {
  var query = client.query('SELECT * FROM USERS WHERE USER_ID=$1', [id]);
  query.on('row', function(row, result) {
    result.addRow(row);
  });
  query.on('end', function(result) {
    callback(result);
  });
};

My code hits the db and returns the user, but when it goes back up to the async code the user is in the err object. What am I doing wrong? How do I properly set up callbacks?

Upvotes: 0

Views: 160

Answers (1)

robinkc
robinkc

Reputation: 1348

As pointed by damphat, your code should be

//additionally, handle errors 
query.on('error', function(err){
    callback(err) // The first argument to callback should be an error object
})

query.on('end', function(result){
    callback(null, result) //passing null error object
})

Upvotes: 2

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