如何使用数组splice（）函数删除对象中的子数组？

Question

I have written a code that successfully inserts an array (called: "wishlistArray") into an existing Object using the array push() function.

As you can already guess, its triggered when a user wants to add an item to his/her Wish list .

Find below my Object architecture for clarity, that indicates that a user with user ID: "udEnfEmy5DSBvDsSy" has already added the Object to his/her "Wish List"

_id: "DFhcAYAtMBviczogo"
createdDate: "04/12/2017"
expiryDate: "04/22/2017"
noOfViews: 125

   wishListArray: Array[1]
   0: Object
      wishedBy: "udEnfEmy5DSBvDsSy"

To avoid inserting duplicates in the wishlistArray array, I check if the current user ID already exists in the wishlistArray array, as per code below:

var selectedItemIDSet = Session.get('selectedItemIDSet');
var addToWishList = buyList.find(selectedItemIDSet);
var currentUser = [Meteor.user()._id ];

var wheatherWishListedOrNot = buyList.find({ _id:selectedID, 'wishListArray.wishedBy': {$in: currentUser } } ).count();

addToWishList.forEach(function(itemName){

 var currentObjectID = itemName._id; 

        //### If wishListArrayArray array already exists in then...
        if (itemName.wishListArray) {

               var wishListArray = [,...itemName.wishListArray];

                    //### If current user hasnt wish listed item then add to Wish List (wishListArray) array
                if (wheatherWishListedOrNot == "0") { 

                        wishListArray.push({ wishedBy: Meteor.user()._id });
                        Session.set('wishListArrayToGo',wishListArray );

                        }
                else if(wheatherWishListedOrNot == "1") {
                        //### Else if WishedListed by current user, Do absolutely nothing!

                        }   
                }                                  

        var wishListArray = Session.get('wishListArrayToGo');  

        buyList.update(currentObjectID, {$set: {wishListArray: wishListArray} }); 

    });    

Having explained how I've achieved this, I am having issues doing the reverse? How do I remove the user from the wishListArray array?

I have tried the code below without any success.

var selectedItemIDSet = Session.get('selectedItemIDSet');
var removeFromWishList = buyList.find(selectedItemIDSet);

var currentUser = [Meteor.user()._id ];

wheatherWishListedOrNot = buyList.find({ _id:selectedID, 'wishListArray.wishedBy': {$in: currentUser } } ).count();


removeFromWishList.forEach(function(itemName){

 var currentObjectID = itemName._id; 

        //### If wishListArrayArray array already exists in then...
        if (itemName.wishListArray) {

               var wishListArray = [,...itemName.wishListArray];

                    //### If current user current user is on **WishedListArray**, then remove from **WishedListArray** array.
                if (wheatherWishListedOrNot == "1") { 

                        wishListArray.splice({ wishedBy: Meteor.user()._id });
                        Session.set('wishListArrayToGo',wishListArray );

                        }
                else if(wheatherWishListedOrNot == "0") {
                        //### Else if current user isnt on WishedListArray, Do absolutely nothing!

                        }   
                }                                  

        var wishListArray = Session.get('wishListArrayToGo');  

        buyList.update(currentObjectID, {$set: {wishListArray: wishListArray} }); 

    });     

The code where I attempt to remove seems logical to me, but fails to remove the user id from the WishlistArray . Can someone kindly point out where I am going wrong?

Thanks in advance!

Answer 1

You could achieve what you want using simple mongo operators. To make it even simpler you can use an array of Strings as wishList (The userIds).

To insert a user:

buyList.update(currentObjectID, { $addToSet: { wishList: userId} });

addToSet will only insert the userId if not already in there.

and to remove it again:

buyList.update(currentObjectID, { $pull: { whishList: userId } });

How about it?