CODEWITHSUNDEEP
meteor
David Andersson
David Andersson

Reputation: 1246

cursor.observe({added}) with Collection.update() breaks Meteor - why?

I'm trying to use cursor.observe({added}) to calculate a new field based on the inserted fields. Using Docs.update() with the added document breaks if observing on added, Meteor seems to get stop in a loop before imploding. However, updating on changed works.

Why? And how would I go about calculating the new field on insertion?

See comments:

Meteor.startup(function () {
  var cursor = Docs.find();
  var handle = cursor.observe({
    added: function (doc) {
      // This breaks Meteor. Meteor gets stuck in a loop and breaks.
      Docs.update(
        doc._id,
        {$set: {metric: getCalculatedMetric( doc.x, doc.y )}}
      );
      // However, this would log once as expected.
      // console.log(doc.name + ' has been added.');
    },

    changed: function (doc, oldDoc) {
      // This works as expected, updates myField.
      Docs.update(
        doc._id,
        {$set: {metric: getCalculatedMetric( doc.x, doc.y )}}
      );
    }
  });
});

Upvotes: 0

Views: 570

Answers (1)

nate-strauser
nate-strauser

Reputation: 2803

not sure why this would be a problem, but i have something very similiar working using methods

CollectionName.find({}).observe({
        added: function(document){
            Meteor.call('doSomething', {
                id: document._id
            });
        },
        changed: function(newDocument, oldDocument){
            Meteor.call('doSomething', {
                id: newDocument._id
            });
        }
});

if this works for you, if would have the added benefit of removing duplicate calculation code

my method does use a more granular query, but that shouldnt be an issue

doSomething : function(data) {
        if(!data.id)
            throw new Meteor.Error(500, "Missing id!");
        CollectionName.update({_id:data.id}, {$set: {
            'field':value
        }});
},

Upvotes: 1

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