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synchronic node js function

i am quiet new to java script and node js.
i have a problem with a simple function that i call, and it gets done more than one time.
this is my code
app.post('/checkGetSensorIds', function (req, res) {
var tables=['temperature', 'pressure', 'linear_acceleration'];
var ids= [1];
DButils.checkAllSensorsForId(connection, 1 , tables , function(idHasSensorsInfo){
console.log("idHasSensorsInfo is: \n" , idHasSensorsInfo);
});
res.end();
});
/*this function gets a user Id, and the table of all sensors the customer wants, and return true if this
user id has information in all the sesnsor tables that were requested, otherwise returns false*/
exports.checkAllSensorsForId= function(dbConnection, id , sensorsTables, callback){
var sensorsTablesLength= sensorsTables.length;
for (var i = 0; i < sensorsTables.length; i++) {
var tableName= sensorsTables[i];
DButils.checkSingleSensorForId(dbConnection, id, tableName, function(idHasSensorInfo){
if(idHasSensorInfo == false){
callback(false);
return;
}
//in case user have all info in db, we get here and need to return false
if(i == sensorsTablesLength){
callback(true);
return;
}
});
}
};
/*this function gets a user Id, and a single sensor table, and returns true if the user has information
in the requested sensor table, otherwise returns false*/
exports.checkSingleSensorForId= function(dbConnection , id , sensorTable, callback){
var myQuery = 'SELECT count(*) as IdCount FROM ' + sensorTable + ' WHERE id= ' + id;
var query = dbConnection.query(myQuery, function (err, row, result) {
console.log(query.sql);
if (err) {
console.log("checkSingleSensorForId error");
console.error(err);
return;
}
var count= row[0].IdCount;
var idHasSensorInfo = (count > 0);
callback(idHasSensorInfo);
});
};
console.log("idHasSensorsInfo is: \n" , idHasSensorsInfo); is a line that invoked 3 times, while should be only once.
someone has any idea why, and what i need to do to fix it?

You have this line:
DButils.checkAllSensorsForId(connection, 1 , tables , function(idHasSensorsInfo){
console.log("idHasSensorsInfo is: \n" , idHasSensorsInfo);
});
Then you have this:
exports.checkAllSensorsForId= function(dbConnection, id , sensorsTables, callback){
...
for (var i = 0; i < sensorsTables.length; i++) {
...
callback();
...
}
};
So the callback line will be invoked as many times as you call it, which in your case is probably 3 - all it does is call the function from above, so thats why you see it invoked 3 times.
I'm not sure exactly what you are trying to do, but if the callback should be only called once, make sure its ran only once - if it should 'cancel' the for - add a condition to the for or use a promise to resolve whenever you are ready.

javascript - get items with query and match items to a user who has favorited item

I am writing a script on parse.com's javascript cloud code SDK. Here is the information I have saved in my parse.com account and what I am trying to do with it.
I have a bunch of items saved in a parse class called TestItem, theses items have an objectId, item name, meal time (lunch, dinner) and a location for there columns. I also have a class called UserFavourites. In this class the objects have an objectId, item name and a pointer to the user who saved the item as a favourite.
And with this information I am trying to write a cloud code script in javascript. That will match the an item(s) to the item(s) that a user has favourited and send them a push notification saying where and what the item is and the location of the item. I have some code that will do that but this code will send a different notification for each item which could get annoying for the user here is that code.
Parse.Cloud.define("push", function(request, response) {
var TestItem = Parse.Object.extend("TestItem");
var query = new Parse.Query(TestItem);
query.limit(1000);
query.equalTo('school', 'Union College (NY)');
query.find({
success: function(resultsItem) {
//console.log("Successfully retrieved " + resultsItem.length + " :1111.");
for (var i = 0; i < resultsItem.length; i++) {
var object = resultsItem[i];
var item = object.get('item');
var school = object.get('school');
var meal = object.get('meal');
var meal = meal.toLowerCase();
var diningLocation = object.get('schoolMenu');
//var itemArray = [];
var UserFavourite = Parse.Object.extend("UserFavourite");
var queryFavourite = new Parse.Query(UserFavourite);
queryFavourite.limit(1000);
queryFavourite.equalTo("item", item)
queryFavourite.equalTo("school", school)
queryFavourite.find({
success: function(results) {
for (var i = 0; i < results.length; i++) {
var objectFav = results[i];
var user = objectFav.get('user');
var userID = user.id;
var realItem = objectFav.get('item');
console.log(objectFav.get('user'));
console.log(objectFav.get('item'));
var UserClass = Parse.Object.extend("User");
var queryUser = new Parse.Query(UserClass);
queryUser.get(userID, {
success: function(userResult) {
console.log(userResult.get('school'));
console.log('install:' + userResult.get('installation').id);
var userInstallationId = userResult.get('installation').id;
var queryInstallation = new Parse.Query(Parse.Installation);
queryInstallation.equalTo('objectId', userInstallationId);
queryInstallation.find({
success: function(results) {
console.log('number' + results.length);
Parse.Push.send({
// deviceType: [ "ios" ],
where: queryInstallation,
data: {
alert: realItem + " is being served at " + diningLocation + " for " + meal
}
},
{
success: function() {
// Push was successful
},
error: function(error) {
// Handle error
}
});
},
error: function(error) {
console.log('error');
}
});
},
error: function(error) {
console.log('error');
}
});
}
},
error: function(error) {
alert("Error: " + error.code + " " + error.message);
}
});
}
},
error: function(error) {
alert("Error: " + error.code + " " + error.message);
}
});
});
As you can see it is quite long and not very nice looking, I tried to save items to an array so to avoid sending two or more notifications but couldn't get that to work.
So I started writing another script that uses promises which looks much nicer but haven't gotten it all the way right now, it can match the items to users that have an item favourited and put the objectId's of those users in an array. Here is that code.
Parse.Cloud.define("test", function(request, response) {
var UserFavourite = Parse.Object.extend("UserFavourite");
var queryFavourite = new Parse.Query(UserFavourite);
var userArray = [];
var TestItem = Parse.Object.extend("TestItem");
var query = new Parse.Query(TestItem);
query.limit(1000);
query.equalTo('school', 'Union College (NY)');
query.find().then(function(results) {
return results;
}).then(function(results) {
var promises = [];
for (var i = 0; i < results.length; i++) {
var object = results[i];
var item = object.get('item');
var school = object.get('school');
var meal = object.get('meal');
var UserFavourite = Parse.Object.extend("UserFavourite");
var queryUser = new Parse.Query(UserFavourite);
queryUser.equalTo("item", item);
queryUser.equalTo("school", school);
var prom = queryUser.find().then(function(users) {
for (var i = 0; i < users.length; i++) {
var user = users[i];
var userID = user.get('user').id;
if (userArray.indexOf(userID) === -1) {
userArray.push(userID);
}
}
return userArray;
});
promises.push(prom);
}
return Parse.Promise.when.apply(Parse.Promise, promises);
}).then(function(results) {
console.log(userArray);
});
});
But now with this code I don't know where to go, I think using promises and such is the right way to go but I am now confused as once I have all the users that have an item favourited what to do, I then need to get there items that are favourited and are available in the TestItem class, this is where I am struggling.
Here is a pic of my UserFavourite class it has a pointer to the user who favorited the item as you can see, and also a user has more than one favorite.
Thanks a bunch for the help in advance.
Here is your code, and I changed a couple things.
Parse.Cloud.define("getAllFavoriteItems", function (request, response) {
var TestItems = Parse.Object.extend("TestItems");
var UserFavorites = Parse.Object.extend("UserFavorites");
var testItemsQuery = new Parse.Query(TestItems);
var userFavoritesQuery = new Parse.Query(UserFavorites);
testItemsQuery.equalTo('school', 'Union College (NY)');
userFavoritesQuery.include('testItems'); //This makes sure to pull all of the favorite item data instead of just the pointer object
userFavoritesQuery.matchesQuery('testItem', testItemsQuery); //This will run this second query against the TestItems
userFavoritesQuery.limit(1000); //limit results to 1000
userFavoritesQuery.ascending('userId'); //group the user id's together in your array
userFavoritesQuery.find({
success:function(results) {
var pushNotificationMessage = "";
var userId = "";
for (var i=0; i <results.length; i++) {
if (results[i].get('userId') != userId) {
if (results[i].get('userId') != "") {
//TODO send push notification
}
userId = results[i].get('userId');
pushNotificationMessage = ""; //start a new push notification
}
pushNotificationMessage += results[i].get('item').get('name') + ": " + results[i].get('item').get('location') + "\n";
//SOMEWHERE BEFORE HERE I NEED THE INSTALLATION ID OF THE USER
//TO SEND THE PUSH TO THAT USER
Parse.Push.send({
// deviceType: [ "ios" ],
where: queryInstallation,
data: {
alert: pushNotificationMessage
}
},
{
success: function() {
// Push was successful
},
error: function(error) {
// Handle error
}
});
}
response.success(true);
},
error:function(error) {
response.error();
}
})
});
Some code that might create push per user, rough outline though
if (i > 0) {
if (results[i].get('user') === results[i-1].get('user')) {
userItems.push(results[i]);
}
else {
userItems.length = 0;
}
}
else {
userItems.push(results[i]);
}
Not sure let me know if you understand what I'm trying to do...
So it a user has two items favourited I want it to group that into one, phrase that says what and where both items are being served
And here is code to send push
Parse.Push.send({
// deviceType: [ "ios" ],
where: queryInstallation,
data: {
alert: pushNotificationMessage
}
},
{
success: function() {
// Push was successful
},
error: function(error) {
// Handle error
}
});
It can also be done with then/ promises,

I agree with #Maxwell that your UserFavorite should have links to both User and TestItem. This makes it possible to make your cloud-function as simple as:
Parse.Cloud.define("getAllFavoriteItems", function(request, response) {
var TestItem = Parse.Object.extend("TestItem");
var UserFavorites = Parse.Object.extend("UserFavorites");
var testItemsQuery = new Parse.Query(TestItem);
var userFavoritesQuery = new Parse.Query(UserFavorites);
testItemsQuery.equalTo('school', request.params.school);
userFavoritesQuery.include('testItem');
userFavoritesQuery.include('user');
userFavoritesQuery.matchesQuery('testItem', testItemsQuery); //This will run this second query against the TestItems
userFavoritesQuery.find().then(function(results) {
var alerts = {};
for(var i =0 ; i<results.length; i++ ){
var user = results[i].get('user');
var testItem = results[i].get('testItem');
if(user && testItem){
var instId = user.get('installationId');
if(!alerts[instId]) {
alerts[instId] = [];
}
var m = results[i].get('item') + " is being served at {{diningLocation}} for " + testItem.get('meal');
alerts[instId].push(m);
}
}
response.success(alerts);
}, function(error) {
response.error();
});
});
This is working code that you can also find in my github repo.
You can also see the working demo here
The idea is the same as in Maxwell's answer: to have link in UserFavorites class to both User (where installationId is located) and TestItem entities. I've just made it working by including user and testItems properties in query, so when the result is returned filtered by school name I already have a list of installationIds.
Here is my schema:
User
TestItem
UserFavorites
Update:
In this code I added push notifications:
Parse.Cloud.define("getAllFavoriteItems", function(request, response) {
var TestItem = Parse.Object.extend("TestItem");
var UserFavorites = Parse.Object.extend("UserFavorites");
var testItemsQuery = new Parse.Query(TestItem);
var userFavoritesQuery = new Parse.Query(UserFavorites);
testItemsQuery.equalTo('school', request.params.school);
function SendPush(installationId, msg) {
var query = new Parse.Query(Parse.Installation);
query.equalTo('objectId', installationId);
Parse.Push.send({
where: query,
data: {alert: msg}
});
}
userFavoritesQuery.include('testItem');
userFavoritesQuery.include('user');
userFavoritesQuery.matchesQuery('testItem', testItemsQuery); //This will run this second query against the TestItems
userFavoritesQuery.find().then(function(results) {
var groupedAlerts = {};
// manually iterating though results to get alert strings ang group by user in groupedAlerts[installationId]
for(var i =0 ; i<results.length; i++ ){
var user = results[i].get('user');
var testItem = results[i].get('testItem');
if(user && testItem){
var instId = user.get('installationId');
if(!groupedAlerts[instId]) {
groupedAlerts[instId] = [];
}
var m = results[i].get('item') + " is being served at {{dining Location}} for " + testItem.get('meal');
groupedAlerts[instId].push(m);
}
}
// reformat to array and send push notifications
var alerts = [];
for(var key in groupedAlerts) {
alerts.push({
installationId: key,
alerts: groupedAlerts[key],
});
// Send push notifications
SendPush(key, groupedAlerts[key].join());
}
response.success(alerts);
}, function(error) {
response.error();
});
});
I've also updated test data in live demo (just press Get Alerts) or feel free to play around with test data hot it changes cloud code response. gitnub repo is also up to up to date.

This is based on what I understand as the problem you're trying to solve. If it's not addressing the right issue, let me know and I'll see what I can do.
Looking first at your database model, we can simplify this a bit by modifying the UserFavorites table. Starting with the initial two classes, you have a table of items and a table of users. Since a user can favorite many items and an item can be favorited by many users, we have a many-to-many relationship that exists. When this happens, we need to make a third class that points to each of the other two classes. This is where the UserFavorites table comes into play. In Parse terms, the UserFavorites table needs to have two pointers in it: one for the user and one for the item.
Once the UserFavorite table exists with it's two pointers, we can do a few things fairly easily. In your case, we have a few searching criteria:
each item must be at a given school
you want to limit your responses to the first 1000
To accomplish this you can combine two queries into one by calling matchesQuery.
Parse.Cloud.define("getAllFavoriteItems", function (request, response) {
var TestItems = Parse.Object.extend("TestItems");
var UserFavorites = Parse.Object.extend("UserFavorites");
var testItemsQuery = new Parse.Query(TestItems);
var userQuery = new Parse.Query(Parse.User);
var userFavoritesQuery = new Parse.Query(UserFavorites);
testItemsQuery.equalTo('school', 'Union College (NY)');
userQuery.include('Installation');
userFavoritesQuery.include('testItems'); //This makes sure to pull all of the favorite item data instead of just the pointer object
userFavoritesQuery.include('User'); //This makes sure to pull all of the favorite item data instead of just the pointer object
userFavoritesQuery.matchesQuery('testItem', testItemsQuery); //This will run this second query against the TestItems
userFavoritesQuery.matchesQuery('user', userQuery); //This will run the third query against Users, bringing the installation data along with it
userFavoritesQuery.limit(1000); //limit results to 1000
userFavoritesQuery.ascending('userId'); //group the user id's together in your array
userFavoritesQuery.find({
success:function(results) {
...
},
error:function(error) {
response.error();
}
})
})
Once we get that far, then compiling the push message for each user should be a matter of straight-forward string parsing logic. For example, in the success function, one way we can extract the data we is this:
success:function(results) {
var pushNotificationMessage = "";
var userId = "";
for (var i=0; i <results.length; i++) {
if (results[i].get('userId') != userId) {
if (results[i].get('userId') != "") {
//TODO send push notification
}
userId = results[i].get('userId');
pushNotificationMessage = ""; //start a new push notification
}
pushNotificationMessage += results[i].get('item').get('name') + ": " + results[i].get('item').get('location') + "\n";
}
response.success(true);
}
I haven't tested these examples to see if they'll work, but I hope this gives you an idea of how to simplify your queries into something a little more manageable.

How to add JS object into Sqlite database

I am having trouble trying to add a JS Object into an sqlite database. I am using cordova, creating an app for android, windows and iOS.
I have this code for my insert and retrieval...
var data = localStorage.getItem('folderData');
console.log(data);
var username = localStorage.getItem("username");
var session = localStorage.getItem("session_ID");
tx.executeSql('CREATE TABLE IF NOT EXISTS folderData (id integer primary key autoincrement, username, sessionID, folderData text)');
tx.executeSql('SELECT * FROM folderData WHERE username = "'+username+'"', [], function(tx, result) {
if(result.rows.length > 0){
tx.executeSql('UPDATE folderData SET folderData = "'+data+'", sessionID = "'+session+'" WHERE username = "'+username+'"');
alert('An update has occured folderData');
} else {
tx.executeSql('INSERT INTO folderData (username, sessionID, folderData) VALUES ("'+username+'", "'+session+'", "'+data+'")');
alert('An insert has occured folderData');
}
});
tx.executeSql('SELECT folderData FROM folderData WHERE username = "'+username+'" AND sessionID = "'+session+'" ORDER BY id desc LIMIT 1', [], function(tx, result) {
querySuccessFolderData(tx, result);
});
The data variable is my object. When I console.log(data) before insertion i get the following
This my querySuccessFolderData function
function querySuccessFolderData(tx, results) {
var len = results.rows.length;
//alert("folderData table: " + len + " rows found.");
var newFolderData = jsonParse(results.rows.item(0).folderData);
for(i=0;i<len;i++)
{
var newFolderData = results.rows.item(i).folderData;
}
console.log(newFolderData);
}
console.log(newFolderData); now shows up as [Object Object]
What am I doing wrong? Do i need to convert the object again after I select it from the database? This is becoming a nightmare for me now, i've been looking at it for way too long. Any help would be much appreciated.

Managed to fix my issue.
Set my localStorage data.
localStorage.setItem("folderData", JSON.stringify(data['root']));
Used getItem to retrieve it in another function and encoded it for the database insert
var data = localStorage.getItem('folderData');
data = encodeURI(data);
Then used decodedURI and jsonParse to turn it back into an object
var newFolderData = results.rows.item(0).folderData;
newFolderData = decodeURI(newFolderData);
newFolderData = jsonParse(newFolderData);
Which gave me the correct data saved.

Cordova SQL - Select data from multiple table

I have a few tables in my SQLite database and each of them have a foreign key that tie each other.
Lets say the structure are like:
Person
=========
Id
Name
Income
=========
IncomeId
PersonId
Income
Contact
=========
ContactId
PersonId
ContactName
The PersonId in both income and contact table are foreign key to the Person table.
Now when i want to query out the data from all the tables, first i select from Person, then in the callback, i will loop through the data, and select from Income and Contact for each of the record. I can't do a join select as the data are not mandatory, i.e. for a Person it might have income but not contact, or vice versa.
However when i try to run through the loop, i found that the result is always the last instance of the data. After some googling the issue seems to be that i need to use Closure.
I tried to implement it but is having a hard time, currently my code looks like this:
for (var i = 0; i < len; i++){
var profile= results.rows.item(i);
var IdAir = profile["IdAir"];
console.log('processing AIR Id: ' + IdAir);
function queryIncomeSuccess(tx,incomeAirResult, currentLoop){
var lenIncomeAir = incomeAirResult.rows.length;
var incomeAIR = {};
if(lenIncomeAir > 0){
incomeAIR = incomeAirResult.rows.item(0);
}else{
incomeAIR = null;
}
if(currentLoop == len - 1)
{
profile["Income"] = incomeAIR ;
airJson[airJson.length] = profile;
}
};
function queryIncome(tx) {
tx.executeSql("SELECT * FROM Income WHERE IdAir = ?",
[IdAir], function(resultSet){
queryIncomeSuccess(tx,resultSet,i);
}, errorCB);
};
db.transaction(queryIncome, errorCB);
}
Is there any guide for multiple select for Cordova? Any help is greatly appreciated. Thanks.

Am able to get this done by using nested function and closure.
The thing to note is that, the closure need to apply at the db.transaction function, rather than on the success callback only.
Code structure used:
//inside for loop of first select result
for (var i = 0; i < len; i++){
function buildSuccessCallback(current,profile){
return function(tx, result){
querySuccess(tx, result,current,profile);
};
}
function querySuccess(tx,result,currentIdx,profile){
//...perform logic
console.log('currentIdx: ' + currentIdx); //returning the correct value
console.log('current Id: ' + profile["IdAir"]); //returning the correct Id
}
db.transaction((function(i,profile){
return function(tx){
tx.executeSql(mySQL, [profile["IdAir"]], buildSuccessCallback(i,profile), errorCB);
};
})(i,profile), errorCB);
}
Thanks.

How To handle result set of websql in html 5?

I m creating mobile web application using html5 and javascript.I m having two javascript files. AttributesDatabase.js and AttributeView.js.From AttributeView.js i m calling one function from AttributeDatabase.js in that i m executing one select query.Now the query result should go to AtttributeView.js.But the Websql transaction is asynchronous call that is what it is not returning proper result.Is there any way to handle the websql result.
Please help if any way there?
Edited
AttributeView.js
var AttributeDAOObj = new AttributeDAO();
AttributeDAOObj.GetAttributeList();
alert(AttributeDAOObj.GetAttributeList()); //This alert is coming as undefined.
AttributeDAO.js
this.GetAttributeList = function () {
var baseDAOObj = new BaseDAO();
var query = "SELECT AttributeName FROM LOGS";
// this.Successcalbackfromsrc = this.myInstance.Successcalback;
var parm = { 'query': query, 'Successcalback': this.myInstance.Successcalback };
baseDAOObj.executeSql(parm);
}
//To Create database and execute sql queries.
function BaseDAO() {
this.myInstance = this;
//Creating database
this.GetMobileWebDB = function () {
if (dbName == null) {
var dbName = 'ABC';
}
var objMobileWebDB = window.openDatabase(dbName, "1.0", dbName, 5 * 1024 * 1024);
return objMobileWebDB;
}
//Executing queries and getting result
this.executeSql = function (query) {
var objMobileWebDB = this.myInstance.GetMobileWebDB();
objMobileWebDB.transaction(function (transaction) {
//In this transaction i m returning the result.The result value is coming.
transaction.executeSql(query, [], function (transaction, result) { return result; }, this.Errorclback);
});
}
}

The problem is in you succes call back (like in the comment to your question, stated by DCoder)
function (transaction, result) { return result; }
this is returning where to?
So this is how to do it (or at least one way)
you can do for example:
function (transaction,result){
console.log("yes, I have some result, but this doesn't say anything, empty result gives also a result");
// so check if there is a result:
if (result != null && result.rows != null) {
if (result.rows.length == 0) {
// do something if there is no result
}else{
for ( var i = 0; i < result.rows.length; i++) {
var row = result.rows.item(i);
var id = result.rows.item(i).id; //supposing there is an id in your result
console.log('Yeah! row id = '+id);
}
}
}else{
// do something if there is no result
}
};
note the code above can be compacter, but this is how to understand it better.
another way is to put this function is a seperate piece of code, so you keep the sql statement more compact and readable. Like you call you error callback this can be in your function (with this. in front of it) or a completely seperate function.