How to check if value already exists? - angularjs

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.

Related

React Promise Return Firebase Array

I am having a really hard time solving this issue I'm currently having. You see, I am using Firebase as my database to store and fetch data.
Right now, I want to be able to return an array that is being made inside a Firebase .once call, but I am having some difficulties. This is my code so far:
Calling the function (a return function):
<p>{this.fetchStartingPrice(singleProduct.id)}</p>
This is where I want to display the specific value, that I am trying to fetch down below:
fetchStartingPrice(category){
let promises = [];
promises.push(this.fetchPrices(category));
Promise.all(promises).then(result => {
console.log(result);
})
}
I have just used a console.log in an attempt to troubleshoot errors.
fetchPrices(category){
var allPrices = [];
allProductsFirebase.child(category).once('value', (snapshot) => {
snapshot.forEach((childSnapshot) => {
if(childSnapshot.key == category){
allPrices.append(childSnapshot.val().brand);
}
});
return allPrices;
})
}
So basically, I want to loop through the allProductsFirebase in an attempt to first identify the brand of the product, and if it matches with the brand that has been used as a parameter in fetchStartingPrice() and fetchPrises(), I want to store the specific price of that product in an array of numbers (prices). After I have looped through the whole snapshot, I want to return the full array containing only product prices, and then through fetchStartingPrice(), I want to use Math.min(promises) to grab the lowest number in that array. However, I am having a really hard time doing this. Could someone please help me with this?
I want to be able to then, after all of this, return the value in fetchStartingPrice().
fetchPrices() must return Promise or be Promise. you are returning nothing from fetchPrices() ( you are returning allPrices in the .once() scope ). try to return the result ( if it returns Promise ) that .once() returns.
fetchPrices(category){
var allPrices = [];
return allProductsFirebase.child(category).once('value', (snapshot) => {
snapshot.forEach((childSnapshot) => {
if(childSnapshot.key == category){
allPrices.append(childSnapshot.val().brand);
}
});
return allPrices;
})
}

Underscore / Backbone filtering of collection

I'm trying to filter a collection and return the new list so I can render to the page.
I have created a new function on the collection itself but try as I may I cannot get the 2nd IF statement to evaluate TRUE even though I know for sure that there is a match (static match).
I've even tried typeof to make sure that wasn't tripping things up.
Can anyone let me know what I'm missing.
var DisciplinesCollection = Backbone.Collection.extend({
model: Discipline,
filterByCategory: function(cat){
this.each(function(item){
var category = item.attributes.category
console.log(category, cat)
if ('intermediate' == cat){
console.log('static match')
}
if (category == cat){
console.log('dynamic match')
}
});
}
});
I think my issue was the category parameter was a string with a list of potential categories separated by a space. Once I moved these items into a nested object my code was working correctly. Final code example for anyone interested:
var DisciplinesCollection = Backbone.Collection.extend({
model: Discipline,
filterByCategory: function(cat){
return _(this.filter(function(data) {
return _.contains(data.get("category"), cat);
}));
}
});

$.grep to return property after match

I couldn't find any instances where this was being done so I'm asking you brainy people out there if there's a nice easy way to do what I'm wanting.
Trying to map two arrays together. One array has a list of the IDs (Foos), and the other array has all the properties (bars) for those IDs. Want to keep everything in my angular controller.
Here's a snippet. I'm trying to match on ID and map into the Name property.
$scope.Foos = $.map($scope.Foos, function (foo) {
return {
ID: foo.ID,
Name: $.grep($scope.bars, function(b){
return b.ID === foo.ID;
}).Name,
Property: $.grep($scope.bars, function(b){
return b.ID === foo.ID;
}).Property
};
});
What I understand is that $.grep will return the object based on the criteria, can I then call properties of that returned object?
Update:
Foos is ID (guid)
Bars is ID(guid), Name & Property
$.grep returns an array, not an object, so to do what you are wanting you would need to do something like:
Name: $.grep($scope.bars, function(b){
return b.ID === foo.ID;
})[0].Name
The problem here however is if there is no match , $.grep will return an empty array and you will end up throwing an error trying to get the first element from that empty array.
You really should look the properties up first, not while trying to build a more complex object
Something like:
$scope.Foos = $.map($scope.Foos, function (foo) {
// first filter the array
var bars = $.grep($scope.bars, function (b) {
return b.ID === foo.ID;
});
// now test we have result, if not make it ... empty string???
var name = bars.length ? bars[0].Name : '';
// do similar for `Property`
return {
ID: foo.ID,
Name: name,
......
};
});
This could also be modified to have some utility functions like getNameFromBars() and put the $.grep in there and return value found or the default.
If you wanted to get rid of jQuery you could use Array.prototype.map() and Array.prototype.filter() to replace $.map and $.grep.
Also $filter could be used.

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);
});

Backbone - trying to make a filter on a collection with nested object

i'm trying to filter a collection which has models with some nested object. Unfortunately, my result are always empty.
So my models returned in the collection are build like this:
My goal is simple:
I have a view with a list of tag and a content view with all the questions. When a user click on tag, for example, "c#", i want to filter my collection to just return questions with tag "c#"
Before i was doing a fetch on my server and it was working fine, but it was not optimize.
I already have a collection with all the questions so why make a new call, a filter is a better solution i think.
But i didn't succeded with my filter and i don't know if it's possible to do. For now i put my filter in my router because it's more easy to test.
i can't make a filter like this because i have an array of object
getQuestionsByTags: function(query) {
var test = this.questionsCollection.filter(function(model) {
return model.attributes.tags.name == query;
})
console.log('result');
console.log(test);
},
So i was thinking to make a loop but my result is always an empty array.
getQuestionsByTags: function(query) {
var test = this.questionsCollection.filter(function(model) {
_.each(model.attributes.tags, function(tag) {
return tag.name == query;
})
})
console.log('result');
console.log(test);
},
It's maybe simple, but i don't know what to do.
Thanks in advance :)
i've just found a solution that work.
getQuestionsByTags: function(query) {
var flag;
var test2 = this.questionsCollection.filter(function(model) {
flag = false;
_.each(model.attributes.tags, function(tag) {
if(tag.name == query) {
flag = true;
}
})
if(flag) {
return model.attributes;
}
})
console.log('result');
console.log(test2);
},
i put a flag. If he turn true inside the loop, the model has this tag so i return it.
I think it's not very conventional, so if someone have another solution, feel free to post it :)

Resources