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javascript - JSON file use a value only if key exists

I'm retrieving an OSM Json from an overpass call, to obtain a list of features that I have to save on a database. Since the data are very different from one another (for example, some of them do have a a tag called "addr:city", and some of them not), I would like to check if a key exists, and only in that case save the corresponding value. I've found only this question but it's not my case, since I do not know a priori which keys one element will have and which not, and since I'm working with a great load of data, I really can't check the elements one by one and of course I can't write an IF for each case.
Is there a way to solve this? I was thinking something about "if key has null value, ignore it", while looping over the elements, but I don't know if something like that exists
EDIT:
This is my query:
https://overpass-api.de/api/interpreter?data=[out:json][timeout:25];(node[~%22^(tourism|historic)$%22~%22.%22](44.12419,%2012.21259,%2044.15727,%2012.27696);way[~%22^(tourism|historic)$%22~%22.%22](44.12419,%2012.21259,%2044.15727,%2012.27696););out%20center;
and this is the code I'm using to save the data on firebase:
results.elements.forEach(e=>{
var ref = firebase.database().ref('/point_of_interest/');
var key = firebase.database().ref().child('point_of_interest').push().key;
var updates = {};
var data = {
città: e.tags["addr:city"],
tipologia: e.tags["amenity"],
indirizzo: e.tags["addr:street"],
nome: e.tags["name"],
lat: e.lat,
lon: e.lon
}
updates['/point_of_interest/'+key] = data;
firebase.database().ref().update(updates);
})
"results" is the response in json format

You could use something like that:
var attrs = ["addr:city", "amenity", "addr:street", "name"];
var labels = ["città", "tipologia", "indirizzo", "nome"]
var data = { };
attrs.forEach((a, i) => {
if (e.tags[a]) { data[labels[i]] = e.tags[a]; }
});
You could even make this more dynamic, if you can query the attribute names and labels from somewhere.

How can I delete specific rows in parse.com?

I have objects in Parse called "Post" and within that, I have columns called "title" and "content". I am trying to ask the user for an input value and save this as "remove". If the user's input value ("remove") matches a "title" value already saved in parse.com, I want to delete the entire row in parse, so that both the "title", "content" and everything else in the row is deleted. The deleting part is not working so I am wondering if my code is actually making it go through all the data saved in parse and find the one that matches the user's input and then delete it.
What am I doing incorrectly and what can I change to make it delete the entire row?
Thank you in advance.
function getPosts(){
var query = new Parse.Query(Post);
query.find({
success: function(results){
for(var i in results){
var title = results[i].get("title");
var content = results[i].get("content");
var remove = $("#post-remove").val();
console.log("Remove: "+remove);
console.log("MAC Address: " +title);
console.log("place: "+content);
if (title == remove)
{
window.alert("The MAC address matches.");
console.log(remove+" matches " + title+ " and is located in " +content);
var Post = Parse.Object.extend("Post");
var query = new Parse.Query(Post);
query.find("objectId", {
success: function(yourObj){
//console.log(yourObj);
//Post.destroy({}); //if title matches remove, delete the Post (title and content) (but it's not deleting it)
Post.remove("title");
Post.remove("content");
}
});
}
}
}
});
}

To clarify and add a bit to #JakeT's acceptable answer:
1) find objects to delete like this:
function postsMatching(title) {
var Post = Parse.Object.extend("Post");
var query = new Parse.Query(Post);
query.equalTo("title", title);
return query.find();
}
2) Delete an array of parse objects like this:
Parse.Object.destroyAll(posts);
3) Put the two ideas together (returning a promise to find then delete) like this:
var title = $("#post-remove").val();
postsMatching(title).then(function(posts) {
console.log("deleting " + JSON.stringify(posts));
Parse.Object.destroyAll(posts);
}, function(error) {
console.log("error " + JSON.stringify(error));
});

First of, you can use the Parse.Query.equalTo(key, value) method to filter for the Post/s you are looking for. That will render a lot of your logic unnecessary.
Additionally, since most parse calls are asynchronous, I would suggest learning about Parse Promises and using those instead of the call backs you're using.
Finally, you don't need a second nested query, since you already have the object you are trying to destroy. You just need to call destroy() on that object, and if you have some extra content you need to take care of deleting (i.e., your 'content' is a pointer to another object that is owned only by the Post you are deleting), you should set up a beforeDestroy() trigger for the Post object in your cloud code that will delete that pointer as well.

Parse.com issues while querying array of pointers, .include not getting nested pointer data in cloud code

I am having trouble getting data from the nested pointers in my array of pointers from a query. I have an array of pointers like so: [{"__type":"Pointer","className":"QuizData","objectId":"rmwJrV55c7"},{"__type":"Pointer","className":"QuizData","objectId":"2132q8i9np”}, etc…]
That QuizData class also has a column named “ad” which is a Pointer to the “Ads” class. I can get the QuizData in a query using the following include statements on my query like so:
var __quizAdQueueQuery = new Parse.Query(QuizAdQueue);
__quizAdQueueQuery.equalTo("user", __request.user);
__quizAdQueueQuery.include("quizAdArr”);
__quizAdQueueQuery.include(["quizAdArr.QuizData"]);
BUT Neither of these or both combined don’t work as when I try to get column data from the ad it’s always undefined:
__quizAdQueueQuery.include(["quizAdArr.QuizData.ad"]);
__quizAdQueueQuery.include(["quizAdArr.QuizData.Ads"]);
This is my return from that query, where the column data "mediaType" that I am trying to access is always undefined:
return __quizAdQueueQuery.first().then(function(__resultsObj)
{
__quizQueueObj = __resultsObj;
__userQuizQueueArr = __quizQueueObj.get("quizAdArr");
var __quiz;
var __ad;
var __seenAd;
var __lengthInt = __userQuizQueueArr.length;
var __mediaTypeStr = __request.params.mediaType;
var __matchedQuizzesArr = [];
for (var __i = 1; __i < __lengthInt; __i++)
{
__quiz = __userQuizQueueArr[__i];
// console.log('__quiz.get("name") = '+__quiz.get("name"));
__ad = __quiz.get("ad");
// console.log("__ad.id = "+__ad.id);
//THE MEDIA TYPE IS ALWAYS RETURNING UNDEFINED HERE!!!
console.log('__ad.get("mediaType") = '+__ad.get("mediaType")+', __mediaTypeStr = '+__mediaTypeStr);
if (__ad.get("mediaType") == __mediaTypeStr)
{
//put all matches in array to be sorted
__matchedQuizzesArr.push(__userQuizQueueArr[__i]);
console.log("__matchedQuizzesArr.length = "+__matchedQuizzesArr.length);
}
}
return __matchedQuizzesArr;
});
Thanks for any help you can give! I also posted this as a bug in the Parse/Facebook issue reporter but was redirected here, so if this is a bug I can reopen it: https://developers.facebook.com/bugs/923988310993165/
EDIT Here is the updated, working query with nested includes for clarity:
var __quizAdQueueQuery = new Parse.Query(QuizAdQueue);
__quizAdQueueQuery.equalTo("user", __request.user);
__quizAdQueueQuery.include('quizAdArr');
__quizAdQueueQuery.include('quizAdArr.ad');

This should work (you only need to list the column names):
query.include('quizAdArr.ad');
Here's why:
You're querying QuizAdQueue so you don't need to list that
The QuizAdQueue class has an array in quizAdArr so you include it: query.include('quizAdArr');
Each quizAdArr element is a QuizData with an ad so you include it: query.include('quizAdArr.ad');
The issue was that you were including QuizData which is the name of a class and not a column name

angular check if item exists in scope (array) already

I'm trying to check if I have something in an array already before adding - so that I cannot add the same type more than once. I am checking the model of the drop down I am selecting from against the array I am storing everything in (there is a slight difference in that the model stores the id as id and the array as skillId).
I am basically just trying to look through the array and see if the id matches - and if it does do not add the item to the array. Here is the code.
$scope.saveSkill = function() {
//send skill to get path, then add to skills array
console.log($scope.pathArray);
console.log($scope.scope5.id);
var skillCheck = true;
//check if exists aready
for(i=0;i<$scope.pathArray.length;i++){
if($scope.pathArray[i].skillId = $scope.scope5.id ){
console.log("Cannot add same skill more than once");
skillCheck = false;
}
}
if(skillCheck){
$http({
method: 'GET',
url: '/findPathScopeToSkill/' + $scope.scope5.id + "/1"
})
.success(function(data){
angular.forEach(data.paths, function(index) {
$scope.pathArray.push(index);
});
});
}
};
Just as a quick reference - pathArray is where the items get pushed into and where I do not want to have doubles - so I am checking the current id vs the id's inside the array (only difference is they are .skillId's)
I can add one, then can't add the same one again BUT I also can't add any after that. Can't seem to figure out what I am doing wrong here. Any help would be greatly appreciated. Thanks!

Dynamic Variable Names with JavaScript - Two arrays?

I'm trying to generate markers for every user in my $.each loop in such a way that I can select each marker using the corresponding userId of a given user.
$.each($.parseJSON(window.usersArray), function (i, user) {
window.userMarkers[user['id']] = L.marker(98.76, 12.34).addTo(map);
console.log(window.userMarkers[user['id']]);
});
EDIT
I get the error:
Cannot set property '3' of undefined, where 3 is the user's ID.

You need to create the object (or array depending on your needs) before you can add anything to it.
window.userMarkers = {};
$.each($.parseJSON(window.usersArray), function (i, user) {
window.userMarkers[user['id']] = L.marker(98.76, 12.34).addTo(map);
console.log(window.userMarkers[user['id']]);
});

Solution: Define the array before setting properties to it! Example:
window.userMarkers = new Array();