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personally this seems very odd to me. I'm currently querying my Elastic search database to get some indexed records, everything works fine and I get my response back filled with hits.

Now I would like to manipulate the response and add a string to the JSON object after I've got the document back from elastic search. Currently this is my code:

var list = response.hits.hits;
for (var i = 0; i < list.length; i++) {
  var compSlug = '';

  var query = Company.findById(list[i]._id);
  var promise = query.exec();

  promise.then(function(comp) {
    list[i]._source.slug = comp.slug;
  });

  console.log(list[i]._source);               // this is line 142
  console.log(list[i]._source.title);         // this is line 143
}

This code, the console.log(list[i]._source); displays what I'm expecting to see, the entire indexed document. But the other console.log with list[i]._source.title returns undefined.

Also I get the following error: Unhandled rejection TypeError: Cannot read property '_source' of undefined on the last console.log line.

Below is the full stack trace of the error:

Unhandled rejection TypeError: Cannot read property '_source' of undefined
at search.controller.js:143:11
at tryCatcher (/Users/lucaswelander/Desktop/tsearch/node_modules/bluebird/js/release/util.js:16:23)
at Promise._settlePromiseFromHandler (/Users/lucaswelander/Desktop/tsearch/node_modules/bluebird/js/release/promise.js:504:31)
at Promise._settlePromise (/Users/lucaswelander/Desktop/tsearch/node_modules/bluebird/js/release/promise.js:561:18)
at Promise._settlePromise0 (/Users/lucaswelander/Desktop/tsearch/node_modules/bluebird/js/release/promise.js:606:10)
at Promise._settlePromises (/Users/lucaswelander/Desktop/tsearch/node_modules/bluebird/js/release/promise.js:685:18)
at Async._drainQueue (/Users/lucaswelander/Desktop/tsearch/node_modules/bluebird/js/release/async.js:138:16)
at Async._drainQueues (/Users/lucaswelander/Desktop/tsearch/node_modules/bluebird/js/release/async.js:148:10)
at Immediate.Async.drainQueues [as _onImmediate] (/Users/lucaswelander/Desktop/tsearch/node_modules/bluebird/js/release/async.js:17:14)
at processImmediate [as _immediateCallback] (timers.js:383:17)

Why do I get the error on line 143 but not on line 142? It must be something with that ._source is undefined obviously, but why do I get this error when I clearly see that _source is not undefined?

Lucas Reppe Welander
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  • There are no line numbers in your code. – Val Aug 17 '16 at 12:26
  • ive updated it for you, but if you would've read the whole question you would have know what the two lines are the ones that giving the error, especially when I pasted the whole stack trace. – Lucas Reppe Welander Aug 17 '16 at 12:47
  • Rest assured, I did read the whole question. But if you mention line numbers, they should be there, otherwise that's just noise to people reading your question ;-) Help us help you ! – Val Aug 17 '16 at 12:48
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    One thing that will not work correctly in your code is that once the line 139 (within the promise) will execute it will not be clear what the value of `i` is since the for-loop might still be running, or worse could be finished and `i` would be equals to `line.length` – Val Aug 17 '16 at 12:50
  • Dupe of https://stackoverflow.com/questions/23667086/why-is-my-variable-unaltered-after-i-modify-it-inside-of-a-function-asynchron – JohnnyHK Aug 17 '16 at 12:54

0 Answers0