Querying OCB from JavaScript (WireCloud)

Question

I'm trying to get type fields for each attribute of my entities. Quering Orion and getting entities is not the problem (I do this through NGSI Source widget) but the way getting these parameters.

From NGSI Source (usual suscription to Orion instance):

 var doInitialSubscription = function doInitialSubscription() {

    this.subscriptionId = null;

    this.ngsi_server = MashupPlatform.prefs.get('ngsi_server');
    this.ngsi_proxy = MashupPlatform.prefs.get('ngsi_proxy');
    this.connection = new NGSI.Connection(this.ngsi_server, {
        ngsi_proxy_url: this.ngsi_proxy
    });

    var types = MashupPlatform.prefs.get('ngsi_entities').split(new RegExp(',\\s*'));
    var entityIdList = [];
    var entityId;
    for (var i = 0; i < types.length; i++) {
        entityId = {
            id: '.*',
            type: types[i],
            isPattern: true
        };
        entityIdList.push(entityId);
    }
    var attributeList = null;
    var duration = 'PT3H';
    var throttling = null;
    var notifyConditions = [{
        'type': 'ONCHANGE',
        'condValues': MashupPlatform.prefs.get('ngsi_update_attributes').split(new RegExp(',\\s*'))
    }];
    var options = {
        flat: true,
        onNotify: handlerReceiveEntity.bind(this),
        onSuccess: function (data) {
            this.subscriptionId = data.subscriptionId;
            this.refresh_interval = setInterval(refreshNGSISubscription.bind(this), 1000 * 60 * 60 * 2);  // each 2 hours
            window.addEventListener("beforeunload", function () {
                this.connection.cancelSubscription(this.subscriptionId);
            }.bind(this));
        }.bind(this)
    };
    this.connection.createSubscription(entityIdList, attributeList, duration, throttling, notifyConditions, options);
};
 var handlerReceiveEntity = function handlerReceiveEntity(data) {
    for (var entityId in data.elements) {
        MashupPlatform.wiring.pushEvent("entityOutput", JSON.stringify(data.elements[entityId]));
    }
};

To MyWidget:

MashupPlatform.wiring.registerCallback("entityInput", function (entityString) {
    var entity;
    entity = JSON.parse(entityString);
    id = entity.id;
    type = entity.type;
    for(var attr in entity){
        attribute = entity[attr];
    }

I'm trying to code something similar to obtain the value of type fields. How can I do that? (I'm sure it's quite easy...)

Answer 1

You cannot make use of the current NGSI source operator implementation (at least v3.0.2) if you want to get the type metadata of attributes as the NGSI source makes use of the flat option (discarding that info).

We are studying updating this operator to allow creating subscriptions without using the flat option. The main problem here is that other components expect the data provided by this operator being provided in the format returned when using the flat option. I will update this answer after analysing deeper the issue.