I am tryng to create posts using a for loop, but when i look at Parse database only the last object of my array get's stored. this is the code i wrote.
var Reggione = Parse.Object.extend("Reggione");
var creaReggione = new Reggione();
var selectobject = $('#searcharea')[0];
for (var i = 2; i < selectobject.length; i++) {
creaReggione.set("name", selectobject.options[i].text);
creaReggione.save();
Thanks, Bye.
Do this by creating an array of new objects, then save them together...
var newObjects = [];
for (var i = 2; i < selectobject.length; i++) {
creaReggione.set("name", selectobject.options[i].text);
newObjects.push(creaReggione);
// ...
}
Parse.Object.saveAll(newObjects);
Remember, if you want something to happen after saveAll completes (like call response.success() if you're in cloud code), then you should use that promise as follows...
Parse.Object.saveAll(newObjects).then(function(result) {
response.success(result);
}, function(error) {
response.error(error);
});
In extension to danhs answer, the reason this does not work is because only one transaction can happen at a time from the JS client to Parse.
Therefore in your loop the first call to .save() is made and the object is saved to Parse at some rate (asynchrounously), in that time the loop continues to run and skips over your other save calls, these objects are NOT queued to be saved. As Danh pointed out, you must use Parse's batch operations to save multiple objects to the server in one go, to do this you can:
var newObjects = [];
for (var i = 2; i < selectobject.length; i++) {
creaReggione.set("name", selectobject.options[i].text);
newObjects.push(creaReggione);
// ...
}
Parse.Object.saveAll(newObjects);
Hope this helps, I'd also recommend taking a look at Parse's callback functions on the save method to get more details on what happened (you can check for errors and success callbacks here to make debugging a little easier)
An example of this would be to extend the previous call with:
Parse.Object.saveAll(newObjects, {
success: function(messages) {
console.log("The objects were successfully saved...")
},
error: function(error) {
console.log("An error occurred when saving the messages array: %s", error.message)
}
})
I hope this is of some help to you
Related
I am working on a report which generates Diff report URLs everyday(since 2016)
I parse those reports(in JSON) to find some string which indicates regression and mark a flag (regressionFound = true) in the JS. I am then using this flag in the HTML code to show the text as "Regression Found" for the regression that day
The problem is for all the reports whether or not it shows regression shows as regressionFound = false. I assume this is because of getJSON being asynchronous. Any work around this?
for (var j=0; j<reports.length; j++) {
// some code
var ReportPath = buildURL(j);
regressionFound = false
(function(url) {
$.getJSON(url, function (data) {
if (some condition //regression found) {
regressionFound = true;
}
});
})(ReportPath);
}
Consider creating array of the request promises and use $.when() or Promise.all() to run code after all the requests complete. With each request you could add a regressionFound property to each report object
var requests = reports.map(function(report, i){
return $.getJSON(buildURL(i)).then(function (data){
report.regressionFound = // conditional
});
});
$.when.apply(null, requests).then(function(){
// all requests completed and report objects are updated
// loop over reports and modify html
})
I'm new to node.js, so before releasing my node.js app, I need to be sure it will work as it should.
Let's say I have an array variable and I intialize it on beginning of my script
myArray = [];
then I pull some data from an external API, store it inside myArray, and use setInterval() method to pull this data again each 30 minutes:
pullData();
setInterval(pullData, 30*60*1000);
pullData() function takes about 2-3 seconds to finish.
Clients will be able to get myArray using this function:
http.createServer(function(request, response){
var path = url.parse(request.url).pathname;
if(path=="/getdata"){
var string = JSON.stringify(myArray);
response.writeHead(200, {'Content-Type': 'text/plain'});
response.end(string);
}
}).listen(8001);
So what I'm asking is, can next situation happen?:
An client tries to get data from this node.js server, and in that same moment, data is being written into myArray by pullData() function, resulting in invalid data being sent to client?
I read some documentation, and what I realized is that when pullData() is running, createServer() will not respond to clients until pullData() finishes its job?
I'm really not good at understanding concurrent programming, so I need your confirmation on this, or if you have some better solution?
EDIT: here is the code of my pullData() function:
var now = new Date();
Date.prototype.addDays = function(days){
var dat = new Date(this.valueOf());
dat.setDate(dat.getDate() + days);
return dat;
}
var endDateTime = now.addDays(noOfDays);
var formattedEnd = endDateTime.toISOString();
var url = "https://api.mindbodyonline.com/0_5/ClassService.asmx?wsdl";
soap.createClient(url, function (err, client) {
if (err) {
throw err;
}
client.setEndpoint('https://api.mindbodyonline.com/0_5/ClassService.asmx');
var params = {
"Request": {
"SourceCredentials": {
"SourceName": sourceName,
"Password": password,
"SiteIDs": {
"int": [siteIDs]
}
},
"EndDateTime" : formattedEnd
}
};
client.Class_x0020_Service.Class_x0020_ServiceSoap.GetClasses(params, function (errs, result) {
if (errs) {
console.log(errs);
} else {
var classes = result.GetClassesResult.Classes.Class;
myArray = [];
for (var i = 0; i < classes.length; i++) {
var name = classes[i].ClassDescription.Name;
var staff = classes[i].Staff.Name;
var locationName = classes[i].Location.Name;
var start = classes[i].StartDateTime.toISOString();
var end = classes[i].EndDateTime.toISOString();
var klasa = new Klasa(name,staff,locationName,start,end);
myArray.push(klasa);
}
myArray.sort(function(a,b){
var c = new Date(a.start);
var d = new Date(b.start);
return c-d;
});
string = JSON.stringify(myArray);
}
})
});
No, NodeJs is not multi-threaded and everything run on a single thread, this means except non-blocking calls (ie. IO) everything else will engage CPU until it returns, and NodeJS absolutely doesn't return half-way populated array to the end user, as long as you only do one HTTP call to populate your array.
Update:
As pointed out by #RyanWilcox any asynchronous (non-blocking syscall) call may hint NodeJS interpreter to leave your function execution half way and return to it later.
In general: No.
JavaScript is single threaded. While one function is running, no other function can be.
The exception is if you have delays between functions that access the value of an array.
e.g.
var index = i;
function getNext() {
async.get(myArray[i], function () {
i++;
if (i < myArray.length) {
getNext()
}
});
}
… in which case the array could be updated between the calls to the asynchronous function.
You can mitigate that by creating a deep copy of the array when you start the first async operation.
Javascript is single threaded language so you don't have to be worried about this kind of concurrency. That means no two parts of code are executed at the same time. Unlike many other programming languages, javascript has different concurrency model based on event loop. To achieve best performance, you should use non-blocking operations handled by callback functions, promises or events. I suppose that your external API provides some asynchronous i/o functions what is well suited for node.js.
If your pullData call doesn't take too long, another solution is to cache the data.
Fetch the data only when needed (so when the client accesses /getdata). If it is fetched you can cache the data with a timestamp. If the /getdata is called again, check if the cached data is older than 30 minutes, if so fetch again.
Also parsing the array to json..
var string = JSON.stringify(myArray);
..might be done outside the /getdata call, so this does not have to be done for each client visiting /getdata. Might make it slightly quicker.
I use Parse in iOS to run a cloud code method that gets an ID in it's request and receives a number in the response.
The purpose of the cloud code function is to take the request ID and add it to a field of 3 different users.
Here is the cloud code method in Javascript:
amount = 3;
// Use Parse.Cloud.define to define as many cloud functions as you want.
// For example:
Parse.Cloud.define("addToIDs", function(request, response) {
var value = request.params.itemId;
var query = new Parse.Query(Parse.User);
query.ascending("createdAt");
query.limit(100);
query.find({
success: function(results) {
var sent = 0;
for (var i = 0; i < results.length; i++) {
var idlst = results[i].get("idString");
if (idlst != null && idlst.indexOf(value) <= -1) {
idlst += value+"|";
results[i].set("idString", idlst);
results[i].save();
sent = sent+1;
}
if (sent >= amount) {
break;
}
}
response.success(sent);
},
error: function() {
response.error("Test failed");
}
});
});
When running this cloud code method I get a response of '3' meaning it called .save for 3 users. The problem is that when i go back to look in the Database viewer in the parse website it actually only updated a single user (Its always the same user). No matter how many times i run this code, it will only actually update the first user..
Anyone know why this is happening?
Both save and saveAll are asynchronous, so you should make sure the saving process is done.
Also note that, the user object can only be updated by the owner or request with masterkey.
The following code should work:
var amount = 3;
Parse.Cloud.define("addToIDs", function(request, response) {
var value = request.params.itemId;
var query = new Parse.Query(Parse.User);
query.ascending("createdAt");
query.limit(100);
return query.find()
.then(function(results) { // success
var toSave = [];
var promise = new Parse.Promise();
for (var i = 0; i < results.length; i++) {
var idlst = results[i].get("idString");
if (idlst != null && idlst.indexOf(value) <= -1) {
idlst += value+"|";
results[i].set("idString", idlst);
toSave.push(results[i]);
}
if (toSave.length >= amount) {
break;
}
}
// use saveAll to save multiple object without bursting multiple request
Parse.Object.saveAll(toSave, {
useMasterKey: true,
success: function(list) {
promise.resolve(list.length);
},
error: function() {
promise.reject();
}
});
return promise;
}).then(function(length) { // success
response.success(length);
}, function() { // error
response.error("Test failed");
});
});
The reason this is happening is two-fold:
save() is an asynchronous method, and
response.success() will immediately kill your running code as soon as it's called.
So what's happening is that inside your for loop you're running save() several times, but since it's asynchronous, they're simply thrown into the processing queue and your for loop continues on through. So it's quickly throwing all of your save()'s into the processing queue, and then it reaches your response.success() call but, by the time it's reached, only one of the save()'s has had a chance to successfully process.
Im trying to send a push message to everyone with read access every time a new note is saved.
In pseudocode it should get the ACL. Evaluate each member in the ACL and return an array of all users with read access. Then send a push notification to each member.
I've tried running separate task one by one and it works properly. However when I put everything together in the following code I get strange results. Looking at the log I can see it not executing in order as I expect. I first though the getACL call was an asynchronous call so I tried to implement promises with no luck. Then after help from stackoverflow I find out that getACL is not asynchronous therefore the code should just work, right?
This is what I'm trying:
Parse.Cloud.afterSave("Notes", function(request) {
var idsToSend = [];
var i = 0;
console.log("1 start");
var objACL = request.object.getACL();
var ACLinJSON = objACL.toJSON();
console.log("2 ACL = " + ACLinJSON);
for (var key in ACLinJSON) {
if (ACLinJSON[key].read == "true") {
idsToSend[i] = key.id;
console.log("3 i = " + i + " = " + idsToSend[i]);
i++;
}
}
console.log("4 idsToSend = " + idsToSend);
//lookup installations
var query = new Parse.Query(Parse.Installation);
query.containedIn('user', idsToSend);
Parse.Push.send({
where: query,
data: {
alert: "note updated"
}
}, {
success: function() {
console.log("Success sent push");
},
error: function(error) {
console.error("can’t find user"); //error
}
});
});
And this is the response I see from parse log
I2014-08-04T08:08:06.708Z]4 idsToSend =
I2014-08-04T08:08:06.712Z]2 ACL = [object Object]
I2014-08-04T08:08:06.714Z]1 start
I2014-08-04T08:08:06.764Z]Success sent push
Everything is completely out of order??
How can I execute the above function in the way it's written?
I've found the logs are not in order when I run things too, could be a timing issue or something, ignore the order when they're in the same second, I have done other tests to confirm things really do run in order on my own Cloud Code... had me completely confused for a while there.
The issue you're having is that log #3 is never being hit... try tracing ACLinJSON on it's own to see the actual structure. When you append it to a string it outputs [object Object] as you have seen, so do console.log(ACLinJSON); instead.
Here's the structure I've seen:
{
"*":{"read":true},
"Administrator":{"write":true}
}
Based on that I would expect your loop to work, but it may have a different level of wrapping.
UPDATE:
Turns out the issue was looking for the string "true" instead of a boolean true, thus the fix is to replace the following line:
// replace this: if (ACLinJSON[key].read == "true") {
if (ACLinJSON[key].read == true) {
This LOOP queries the Parse.com server & then plays with the results if any. The problem is that when nArray is greater than 100, the function exceeds the query/burst limit of Parse.com CloudCode & it fails.
One idea would be to delay the LOOP for a second after every 100 LOOPS, but I'm not sure how to do that. Any other solutions would be greatly appreciated.
Thanks in Advance,
for (var k = 1; k < nArray.length; k++) {
(function (k, mArray) { // <-- define an inline function
query2.equalTo("username", nArray[k]); // BURST LIMIT EXCEEDS
query2.find({
success: function (results) {
if (results.length !== 0) {
var object = results[0];
var compareUserEmail = object.get('email');
if (compareUserEmail !== userEmail) {
// alert("The result is equal to" + object.get('Name'));
mArray.push({
name: object.get('Name'),
email: object.get('email'),
bloxID: object.get('bloxID')
});
gameScore.set("filtered", mArray);
gameScore.save(null, {
success: function (gameScore) {
response.success("Success!");
alert('New object created with objectId: ' + gameScore.id);
},
error: function (gameScore, error) {
alert('Failed to create new object, with error code: ' + error.description);
}
});
}
};
},
error: function () {}
});
})(k, mArray);
// <-- call it after definition using (k)
};
You've got a couple of issues to deal with.
The reason Parse.com doesn't support setInterval is because that would be inviting disaster. It terminates your Cloud Code if it takes too long, so letting you add delays would just increase the chance your code is terminated before completion.
The reason Parse.com has a burst limit is that this usually suggest "you are doing it wrong (tm)". In your case you are looping through an array and running a query for each item in the array. Instead you should be using the containedIn method to get all records for the array in one go. If you are getting more than 100 items in your array you can choose to increase the record limit to 1000, but first consider carefully if this is really what you need.
Given that you are modifying a lot of objects and saving them all, consider using the saveAll method to save them all in one hit too.
You might want to consider batching these operations, but be aware of the restrictions on overall duration for Cloud Code.
You can use a setInterval:
var i = 0;
var intervalId = setInterval(function() {
if(i < nArray.length) {
... your code ...
i++;
} else {
clearInterval(intervalId);
}
}, 100); //every 100ms; change it to what you need