How to Store Local Arrays Properly from subsequent requests in AngularJS

Question

I want to have a local array that stores "last messages" (inbox view). In my service i do a GET request that returns a data structure like this:

[{id:1, from_user:1, to_user:2, message:"bar", has_been_read:false}, 
{id:2, from_user:3, to_user:2, message:"foo", has_been_read:false}]

The server only sends last messages with has_been_read == false, this is the code for the service:

$scope.unreadMessages = []

$scope.GetUnreadMessages = function(){

      $localStorage.AllMessages.push($scope.unreadMessages)

       UserService.GetUnreadMessages()
            .success(function (data) {

              data = angular.fromJson(data);
              $scope.unreadMessages.push(data);

              }).
            error(function(error) {         
        //do something
          });
}

$scope.GetUnreadMessages()

Let's say In my given example json above I read id:1 which cause the, has_been_read to become true.. on the next request it will only return the data id:2, which is correct.. but my problem is the new request data replaces ALL my old data. so what i want to happen is, even if i read id:1 unless i deleted it or i have a new message from the same user, I still want to keep it when i make new requests.. I know my code is wrong just don't know how to go about this..

@dfsq can you please give example code im really new to programming — teddybear123
– teddybear123, Commented Jul 1, 2015 at 18:06
@dfsq when i make a Get Request for the conversation of a specific user, the backend sends all of them as true.. so upon clicking the item in my inbox it changes to true.. — teddybear123
– teddybear123, Commented Jul 1, 2015 at 18:12
Ideally the server should send you both read/unread messages, for it is the entity that will keep your clients in sync. With your current implementation each client will exclusively have its own copy of read messages. — Karma
– Karma, Commented Jul 1, 2015 at 18:18

Karma · Accepted Answer · 2015-07-02 07:55:12Z

1

One possible solution is to save the responses grouped by from_user:

.success(function(unreadMessages){
    angular.forEach(unreadMessages, function(unreadMessage){
        // if conversation from a user exists
        if(localStorage.getItem(unreadMessage.from_user)){
            var conversation = JSON.parse(localStorage.getItem(unreadMessage.from_user));
            conversation.push(unreadMessage);
            localStorage.setItem(unreadMessage.from_user, JSON.stringify(conversation));
        } else {
            var conversation = [];
            conversation.push(unreadMessage);
            localStorage.setItem(unreadMessage.from_user, JSON.stringify(conversation));
        }
    });
})

edited Jul 2, 2015 at 7:55

answered Jul 1, 2015 at 18:37

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