Enable and disable subscriptions in real-time to control the amount of cached data and prevent the error message "Uncaught TypeError: Converting circular structure to JSON"

In an attempt to control the cache on the client side, we had the idea of toggling the subscription to a specific Collection on and off by placing the Meteor.subscribe call within a reactive context as recommended in the Meteor documentation - "In addition, calling Meteor.subscribe in a reactive context sets up a subscription which is automatically stopped when the context is invalidated."

However, we encountered the error "Uncaught TypeError: Converting circular structure to JSON" repeatedly.

The sequence of events in our program goes like this:

Appliances = new Meteor.Collection 'appliances'
Alerts = new Meteor.Collection 'alerts'

On the client side

During Meteor.startup, we subscribe to the collection 'appliances'
Meteor.subscribe ('appliances')
We use Appliances.find{}.observe to track changes

When a new item in Appliances is detected, we dynamically subscribe to alerts using Meteor.render and display all alerts associated with that item

Meteor.render(function() {Meteor.subscribe(Alerts); .....}

Can you spot where I may have made a mistake? Open to any suggestions!

Answer №1

I'm not sure about the source of your error message, but you can manage the "only when necessary" subscription easily by utilizing Deps.autorun() along with a Session variable:

You can place this code snippet anywhere on the client:

Deps.autorun(function () {
  if (!Session.get('isViewingAlerts')) Meteor.subscribe('alerts');
});

If you use

Session.set('isViewingAlerts', false)
, it will invalidate the code in the autorun function and trigger its re-execution.

Furthermore, you have the option to subscribe to a specific subset of alerts by including a parameter in the 'alerts' publish function.

EDIT:
I encountered an issue where a Template wasn't reactive when utilizing dynamic subscriptions. We resolved this problem by implementing a callback for Metor.subcribe that updates a Session variable, ensuring that the rendering of the Template is dependent on the subscription being ready for enhanced reactivity.

-Regards, Jan

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