find nth element of array in mongo collection? meteor - arrays

I have a collection called ChatRooms that has an array of chatIds, which are just the user Ids of who is in the chatroom. There are only two ids in the array at a time.
I want to find the first element in this array and set it to the variable "messager" so that i can see if it belongs to the person currently logged in. if not, the message that was just sent will be added to a different collection called notifications, so that the other user can be notified of receiving a message. I keep getting syntax errors on the query, and I don't know why. Here is my block of code:
createMessageNotification = function(message) {
var messager = ChatRooms.find( {}, { chatIds: { $slice: 0,1 } } );
//console.log(messager);
if(messager !== Meteor.userId()){
Notifications.insert({
message: message.value
});
}
}

$slice needs a scalar or an array parameter. docs Also you should be doing a findOne which returns an object instead of a find which returns a cursor.
Try either:
var messager = ChatRooms.findOne( {}, { chatIds: { $slice: 1 } } ).chatIds;
or
var messager = ChatRooms.findOne({}).chatIds[0];

Related

Getting elements from array based on property values (AngularJS)

I have an array of players, each player is an object that has a number of properties, one is "goals".
var players = [
{
"id":"4634",
"name":"A. Turan",
"number":"0",
"age":"28",
"position":"M",
"goals":"1"
},
{
"id":"155410",
"name":"H. Çalhano?lu",
"number":"0",
"age":"21",
"position":"A",
"goals":"0"
},
{
"id":"4788",
"name":"B. Y?lmaz",
"number":"0",
"age":"30",
"position":"A",
"goals":"2",
}
]
I've written a function to cycle through the array and push every element that has more than '0' goals to an array, topScorers. Like so:
$scope.topScorerSearch = function() {
var topScorers = [];
$scope.teamDetails.squad.forEach(function(o) {
if (o.goals > 0) {
topScorers.push(o)
}
});
return topScorers;
}
With the function called as {{topScorerSearch()}}.
This returns only players who have scored. Perfect.
However, I want to run this on other properties, which will result in a lot of repetitious code. How can I make this a general purpose function that can be executed on different properties?
I tried including the 'prop' parameter, but it didn't work:
$scope.topScorerSearch = function(prop) {
var topScorers = [];
$scope.teamDetails.squad.forEach(function(o) {
if (o.prop > 0) {
topScorers.push(o)
}
});
return topScorers;
}
...and called the function like this:
{{topScorerSearch(goals)}}
Why doesn't this work? Where am I going wrong?
I believe the issue is that prop will not resolve to goals because goals is being treated as a variable with a null or undefined value, making prop null or undefined.
If you use the alternative way of accessing object properties object["property"] and use the function {{topScorers("goals")}} it should work out.

iterate each object in array and populate each element of the array with result. asynchronously

I need help with array asynchronous iterate functionality. I working with node-opcua library in nodejs. There is function session.browse(nodeId, result)
Right now code looks like:
NodesTree = {
"NodesTree":{
"name":"SYM:",
"subf":[]
}
};
the_session.browse("ns=1;s=SYM:", function(err, browse_result){
if(!err) {
var buf = [];
browse_result[0].references.forEach(function(reference) {
if (reference1.browseName.namespaceIndex > 1) {
buf.push(reference);
}
});
NodesTree.subf = buf;
}
});
In result I get references of SYM: folder example:
[{"referenceTypeId":"ns=0;i=35","isForward":true,"nodeId":"ns=6;s=S71500ET200MP station_1","browseName":{"namespaceIndex":6,"name":"S71500ET200MP station_1"},"displayName":{"text":"S71500ET200MP station_1","locale":"en"},"nodeClass":"Object","typeDefinition":"ns=0;i=61"}]
I have Nodes structure in opc like this:
->SYM:
-->PLC
--->PLC_name
---->global_tag <variable>
---->global_tag1 <variable>
---->block
------>blok_tag1 <variable>
------>block_tag2 <variable>
Task is make one complete JSON object as tree for further use.
Logic is that: for each element in the references array get nodeId value and browse for references of the element and assign as element.subf = reference.
Final result something like:
NodesTree = {
"NodesTree":{
"name":"SYM:",
"subf":[
{attributes of PCL structure got by **browse**() + subf:[{ attributes of PLC_name by browse(), subf:
[{....and here again attributes and subf] }, {if no subf just assign subf; [] }]
]
}
};
So need call session.browse() for each reference and all finally bind to one object.
I tried to use Async library each and map in series functions to solve all that, but get nothing wise in result. May be there some smart solution can be found by Stack overflow community. Please help.
I am not familiar with node-opcua but assume that session.browse() is also async. Then something like this might work?
var async = require('async');
async.map(buf,
function(reference, callback) {
session.browse(reference.nodeId, function (err, result) {
callback(err, result);
});
}, function(err, results) {
// results is now an array of all single results
NodesTree.subf = results;
});

How to check if value already exists?

I have a small app that users can use to search for a movie, and then add it to their watchlist. Currently it is possible to add 1 movie multple times for the same user. Which ofcourse isn't expected behaviour.
My solution would be to find the unique id of the movie that's being added and crosscheck that with my movies_users data. If the movie_id value exists, do this, else do this.
At the moment I do have the unique movie id of the movie that's being added,
$scope.movieListID = response;
console.log ($scope.movieListID.id)
Which gets ouputted like a string, like so,
314365
And I got the movie records from the current user,
$scope.moviesCheck = response.data;
console.log ($scope.moviesCheck)
Which looks like this,
[{"id":2,"title":"Black Panther", "movie_id":"284054"}]
So what would be a good way to check if the result from $scope.movieListID.id already exists in the $scope.moviesCheck data?
* update *
Trying a suggestion below does not give the expected result.
var exists = function (id) {
$scope.moviesCheck.forEach(function (movie) {
console.log (movie.movie_id)
console.log (id)
if (movie.movie_id === id)
console.log ('duplicate')
else
console.log ('not duplicate')
});
}
exists($scope.movieListID.id);
The console.log output from this is,
312221
312221
not duplicate
Which clearly are duplicate results.
You can add a function in your controller to check if the movie exists in the list
var exists = function (id) {
$scope.moviesCheck.forEach(function (movie) {
if (movie.id === id)
return true;
});
return false;
}
// and call it
exists($scope.movieListID.id); // true or false
I'm not 100% if this is a good way to do this, but for me it works and I think it's pretty low on performance,
movieService.loadMovies().then(function(response) {
$scope.moviesCheck = response.data;
var arr = $scope.moviesCheck
function myIndexOf(o) {
for (var i = 0; i < arr.length; i++) {
if (arr[i].movie_id == o.exisitingMovie_id) {
return i;
}
}
return -1;
}
var checkDuplicate = (myIndexOf({exisitingMovie_id:movie.id}));
if (checkDuplicate == -1) {
From your question I've understood that, based on the object exists using id in the array of object, you have to do different action.
You can use $filter for this. Inject the filter for your controller and assign it to the scope. So this will be available whenever you want in this controller.
$scope.cFilter('filter')($scope.movies, {movie_id:$scope.existingMovie.movie_id}, true);
$sope.movies - is the list of movies passed to the filter. You can
send any list based on your need.
{movie_id:$scope.existingMovie.movie_id} - This one is the object
which one we need to find. This can be based on your need. Since we
are searching movie_id, we need to send the object with property
and value. {movie_id:$scope.existingMovie.movie_id}, Here movie_id is
the property and followed by the value with the colon.
true: This indicates that, to search exact matched values. By default
this is false. If this is set to false, then if we want to search 54
in the movie id, this will returns the objects whichever contains 54
as part of the value.
app.controller('controller', ['$filter',function($filter){
$scope.cFilter= $filter;
$scope.Exists=function(){
$scope.movies=[{"id":2,"title":"Black Panther", "movie_id":"284054"},{"id":3,"title":"Black Panther", "movie_id":"32343"},{"id":4,"title":"Black Panther", "movie_id":"98863"}]
$scope.existingMovie={"id":3,"title":"Black Panther", "movie_id":"32343"};
var _obj=$scope.cFilter('filter')($scope.movies, {movie_id:$scope.existingMovie.movie_id}, true);
if(_obj && _obj[0])
{
Console.log('object exists')
}
else
{
Console.log('Object is not found')
}
}
}])
Many Thanks Jeeva Jsb. This got me on the right track, however I thought I would clarify with a practical example that seems to work as expected.
So I have a function called getData which get the AJAX array but we need to check if the record exist before added to scope (else we get duplicates)
if (d.data.length) {
for (var i = 0; i < d.data.length; i++) {
var doesExist = $filter('filter')($scope.notifications, {NotifId:d.data[i].NotifId}, true);
if (doesExist.length == 0){
$scope.notifications.push(d.data[i]);
}
}
}
This should look familier...
when we are iterating through the returned AJAX object we need to check the ID of the (in my case notificiation)
var doesExist = $filter('filter')($scope.notifications, {NotifId:d.data[i].NotifId}, true);
This line creates a new array by filtering the existing array in scope ($scope.notifications) and passing in the same value from you interation.
If the value exists the object will be copied to the new array called doesExist.
A simple check of length will determine if the record needs to be written.
I hope this helps someone.

get nested object length in an angularFire array in Firebase

I have a Firebase structure like this:
user {
uid {
Lessons {
lid1 {
Title: ...
}
lid2 {
Title: ...
}
}
}
}
I want to use AngularFire to convert user as array so I can filter them using Angular like this:
var usersRef = new Firebase($rootScope.baseUrl + "users");
var userListfb = $firebase(usersRef).$asArray();
The problem is, I also need the number of child of the Lessons object. When I log the userListfb, it is an array. But inside the array, the Lessons node still an object. I can not user length to get its length. What is the correct way to find out the number of child of the Lessons Node with Firebase AngularFire?
Edit 1
According to Frank solution, I got an infinite loop (digest circle error from AngularJS).
The problem is, I will not know the "uid" key. I need to loop it in the first array to get the uid into the second firebaseArray.
Let's say I have a ng-repeat="user in users" in the view and call this on view level in each repeat:
{{getLessonLength(user.uid)}}
Then in the controller, I have this function:
$scope.users = $firebaseArray($scope.usersRef);
$scope.getLessonLength = function (uid) {
var userRef = $rootScope.baseUrl + "users/" + uid + "/lessons/";
var lessonsNode = $firebaseArray(new Firebase(userRef));
return lessonsNode.length;
}
}
And it throw this error: Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting!
Watchers fired in the last 5 iterations: []
All I want it is something like var lessonsCount = snapshot.child('lessons').numChildren() in regular Firebase .on('child_added' ...), the numChildren() function in FirebaseArray. Please help!
AngularFire contains quite some code to ensure that an ordered collection in your Firebase maps correctly to a JavaScript array as Angular (and you) expect it.
If you have a reference to a specific user, you can just create a new sync ($firebase) and call $asArray on that.
var usersRef = new Firebase($rootScope.baseUrl + "users");
var userListfb = $firebase(usersRef).$asArray();
var uid1LessonsRef = userRef.child('uid1').child('Lessons');
var uid1LessonsArray = $firebase(uid1LessonsRef).$asArray();
uid1LessonsArray.$loaded().then(function(arr) {
console.log('Loaded lessons, count: '+arr.length);
});
The data will only be synchronized once, no matter how many references you create to it.

Returning values of a fetch

Please look at the code below. It's a Backbone/Parse code that uses some underscore features.
I'm trying to iterate over an Parse class to retrieve "firstName" attributes of all objects in that class.
I have 2 issues with it.
The first one, as indicated with the comment, is that it correctly retrieves the first names, but it duplicates them. So if there are 5 objects, it will retrieve 5 firstName * 5. There is an iteration problem here. This is shown with the console log.
Second problem, is that I try to push firstName values into an array, then return it, so I can use the values later in code using the testt variable. But checking the testt content with a console log sends a message instead of the firstname lists.
Do you see anyway how to fix this code ?
var DoopizCollection = Parse.Collection.extend({
model: Subscribers
}
);
var doopizlist = new DoopizCollection();
var testt;
testt = doopizlist.fetch({
success: function(doopizlist) {
var results = [];
doopizlist.each(function(object) {
results.push(doopizlist.pluck('firstName'));
console.log(doopizlist.pluck('firstName')); // logs 2 duplicate arrays
});
return results;
},
error: function(doopizlist, error) {
console.log("error"); // The collection could not be retrieved.
}
});
console.log(testt); // logs "a b.promise...." message instead of firstNames
The duplication issue is because you are looping over doopizlist twice, once with each and again with pluck. Pluck is just basically shorthand of the map method.
The second issue is, you are expecting testt is the resulting value, when actually it is an instance of jqXHR, which is something known as a promise. So you can use the then method to log the value of the result.
var DoopizCollection = Parse.Collection.extend({
model: Subscribers
}
);
var doopizlist = new DoopizCollection();
var testt;
testt = doopizlist.fetch({
success: function(results) {
return results.pluck('firstName');
},
error: function(results, error) {
console.log("error"); // The collection could not be retrieved.
}
});
testt.then(function(results) {
console.log(results);
});

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