Question

We’re using Meteor.autorun to look for changes in a ‘filters’ Session variable, make two asynchronous calls to the server for the filtered data and update two ‘list’ Session variables with the results. In another .autorun function, the script waits for changes in the list Session variables, and then turns on applicable templates.

So,

Meteor.autorun(function(){

    set_search_session(Session.get('filters'));

    render_templates(
         Session.get('places'),
         Session.get('awards')
    );

});

var set_search_session = function(filters) {
      Meteor.call('search_places', filters.places, function(error, data) {
          Session.set('places', data);
      };
      Meteor.call('search_awards', filters.awards, function(error, data) {
          Session.set('awards', data);
      };
};

var render_templates = function(places, awards) {
      var filters = Session.get('filters');
      if (!awards && _.isUndefined(filters['neighborhood'])) {
           Session.set('template', 'place_detail');
      };
};

The problem is that the render_templates function is run twice, as it is apparently still dependent on Session.get(‘filters’). So in any autorun function, it looks like you’re unable use a Session.get() function that is separate from the one you’re observing changes on.

Is there a way around this?

Thanks very much for your help.

Answer 1

There are two separate reasons that changing filters calls render_templates. One is that render_templates is called within the same autorun as a Session.get('filters'); the other is that render_templates itself calls Session.get('filters').

To fix the former, split the autorun into two separate autoruns:

Meteor.autorun(function(){
    set_search_session(Session.get('filters'));
});
Meteor.autorun(function(){
    render_templates(
         Session.get('places'),
         Session.get('awards')
    );    
});

To fix the latter, perhaps move the “neighborhoods” field out of Session.get('filters') into its own Session field?