After having pushed elements in array, it is empty

Question

I am getting data from a MySQL query and then pushing the elements into an array. However, once I move out of the query the array is empty. I guess it is because the elements in the array are only references. But how do I keep the elements inside the array?

var timeblocked = [];
var timeunblocked = [];
connection.query("SELECT user_relationships.*, block_intervals.* FROM user_relationships INNER JOIN block_intervals ON user_relationships.id = block_intervals.relationfk WHERE (user1 = '"+currentUserID+"' AND user2 = '"+user2_in_blockedRelationship+"' AND timeunblocked IS NOT NULL)", function(error, resultsForBlock){
  for (var i = 0; i<resultsForBlock.length; i++) {
    timeblocked.push(resultsForBlock[i].timeblocked);
   timeunblocked.push(resultsForBlock[i].timeunblocked);
  }
console.log("1. timeblocked: ", timeblocked, "timeunblocked: ", timeunblocked); // shows all of the elements in the array
});
console.log("2. timeblocked: ", timeblocked, "timeunblocked: ", timeunblocked); //This shows an empty array

Why is the second console.log() NOT logging the array?

you use async function, to get your desire result use callback or promise — sabbir, Aug 17 '17 at 09:47
Okay. I'm pretty new at this. How would you do the query different? — suonpera, Aug 17 '17 at 09:49
Possible duplicate of [How do I return the response from an asynchronous call?](https://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) — Erazihel, Aug 17 '17 at 09:53

score 1 · Answer 1 · answered Aug 17 '17 at 09:49

This is asynchronous behaviour. You should wait to execute the stuff after you completed the callback execution.

Your second console log gets executed before the call to db completed.

Best way is to use the array only after you done with sql call.

connection.query("SELECT user_relationships.*, block_intervals.* FROM user_relationships INNER JOIN block_intervals ON user_relationships.id = block_intervals.relationfk WHERE (user1 = '"+currentUserID+"' AND user2 = '"+user2_in_blockedRelationship+"' AND timeunblocked IS NOT NULL)", function(error, resultsForBlock){
  for (var i = 0; i<resultsForBlock.length; i++) {
    timeblocked.push(resultsForBlock[i].timeblocked);
      timeunblocked.push(resultsForBlock[i].timeunblocked);
  }
console.log("1. timeblocked: ", timeblocked, "timeunblocked: ", timeunblocked); // shows all of the elements in the array



// TODO -- remaining all code that uses the array.

});

Better you use promises if you are not aware.

I thought about doing this, but due to complication of the rest of my code, it would be much easier if I could get this to work, and not add the code inside the query. — suonpera, Aug 17 '17 at 10:41

After having pushed elements in array, it is empty

1 Answers1