Multiple Queries with Parse Cloud Code Using Promises

Question

I have two questions:

Is the below example the right way to execute multiple Parse queries in a single Cloud Code function?
Is the below example going to provide all the data I'm querying with one HTTP request (when I call logbookEntries) and then count as two Parse requests on my account because it's two Parse queries?

Here's the code:

Parse.Cloud.define("logbookEntries", function(request, response) {

  //::: Query 1 :::
  var firstQuery = new Parse.Query("Logbook");
  var returnData = []; 

  firstQuery.find().then(function(firstResults) {
    returnData[0] = firstResults; 

  }).then(function(result) {  

    //::: Query 2 :::
    var secondQuery = new Parse.Query("Logbook"); 
    secondQuery.find().then(function(secondResults))
    returnData[1] = secondResults; 

  }).then(function(result) {
    response.success(returnData);

  }, function(error) {
    response.error(error);

  });
});

Thanks in advance.

Wain · Accepted Answer · 2015-05-18 18:53:41Z

5

It's one way, though not quite correct.
Yes

Your code should really be:

Parse.Cloud.define("logbookEntries", function(request, response) {

//::: Query 1 :::
var firstQuery = new Parse.Query("Logbook");
var returnData = []; 

firstQuery.find().then(function(firstResults) {
   returnData[0] = firstResults; 

   var secondQuery = new Parse.Query("Logbook"); 
   return secondQuery.find();
}).then(function(result) {
   returnData[1] = result; 

   response.success(returnData);

}, function(error) {
   response.error(error);
});

});

Or, a better way to structure it would be:

Parse.Cloud.define("logbookEntries", function(request, response) {

var firstQuery = new Parse.Query("Logbook");
var secondQuery = new Parse.Query("Logbook");

var promises = [];
promises.push(firstQuery.find());
promises.push(secondQuery.find());

Parse.Promise.when(promises).then(function(result1, result2) {
   var returnData = [];
   returnData[1] = result1; 
   returnData[2] = result2; 

   response.success(returnData);

}, function(error) {
   response.error(error);
});

}

edited May 18, 2015 at 18:53

answered May 18, 2015 at 18:33

Wain

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2 Comments

Clifton Labrum Over a year ago

That second example is delightfully simple--thank you! I don't see the wait method in the Parse Promise docs (parse.com/docs/js/api/symbols/Parse.Promise.html) but I assume it means "don't send the response until both promises are fulfilled".

Wain Over a year ago

Sorry, typo, should be when parse.com/docs/js/api/symbols/Parse.Promise.html#.when

Ivan · Accepted Answer · 2018-05-26 11:17:18Z

1

Just to update Wain's structured code: Promise.when returns array when supplied with an array, so the correct code would be

Parse.Promise.when(promises).then(function([result1, result2]) {

and since there is no need to repack the array, it would simply be

Parse.Promise.when(promises).then(function(result) {
   response.success(result);

See here for more info.

edited May 26, 2018 at 11:17

Ivan

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answered May 26, 2018 at 10:59

Vaclav Matouch

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