RxJS 5 - websocket array messages

Question

I receive messages via a websocket connection in this format :

    [
      {
        //msg 1
      },
      {
        //msg 2
      },
      ....
    ]

based on some examples I found on the web here is my code:

public messages: Subject<Message> = new Subject<Message>();
//...
        this.messages = <Subject<Message>>this.wsService
            .connect(COMMUNICATION_URL)
            .map((response: MessageEvent): Message => {
                let data = JSON.parse(response.data);
                //data is an array [ {..} , {..}, ...]
                return data;
            });


        this.messages.subscribe(msg => {
            console.log(msg);
            // msg is an array of objects [ {..} , {..}, ...]
            // I want to be just the object
        });

What I want to achieve is to split the message (array) in objects and when I subscribe I want to receive those objects and not the array of objects.

Community · Accepted Answer · 2017-05-23 11:45:23Z

1

Most easily just use concatAll() or mergeAll() that when used with arrays in RxJS 5 reemits all its items.

this.messages = <Subject<Message>>this.wsService
    .connect(COMMUNICATION_URL)
    .map((response: MessageEvent): Message => {
        let data = JSON.parse(response.data);
        //data is an array [ {..} , {..}, ...]
        return data;
    })
    .concatAll();

I didn't test it but I think you could also use shorter variant:

this.messages = <Subject<Message>>this.wsService
    .connect(COMMUNICATION_URL)
    .concatMap((response: MessageEvent): Message => {
        let data = JSON.parse(response.data);
        //data is an array [ {..} , {..}, ...]
        return data;
    })

See similar answers:

edited May 23, 2017 at 11:45

CommunityBot

11 silver badge

answered Feb 9, 2017 at 18:37

martin

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1 Comment

Doua Beri Over a year ago

I've tested the concatMap example and works like a charm. Thanks

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