Defining array of values in Collection in Meteor

Question

I have defined the following Collection in my application:

Projects = new Mongo.Collection("projects")

In this Collection, I have inserted:

Projects.insert({
    source: "https://upload.wikimedia.org/wikipedia/commons/7/7f/Pug_portrait.jpg",
    title: "pug",
    artist: "pug",
    description: "This piece shows the duality of pug",
    price: "priceless"
});

Projects.insert({
    source: "https://i.sstatic.net/D2ABD.gif",
    title: "doge",
    artist: "doge",
    description: "much doge, many deal with it, wow",
    price: "bout tree fiddy"
})

I am attempting to create an array of the sources of the images using the following helper function:

sourceArray : function () {
          // returns array of sources
          var sources = [];
          for (var i = 0; i < Projects.find().count(); i++) {
            sources.push(images[i].source);
          }
          return sources;

      }

the "images variable is previously defined as: images = Projects.find().fetch();

I then call the helper function in my HTML.

<p>{{sourceArray}}</p>

On the page, the first source appears fleetingly, but disappears within a few seconds. In the browser console the following is shown:

meteor.js:888 Exception in template helper: TypeError: Cannot read property 'source' of undefined
    at Object.Template.body.helpers.sourceArray (http://localhost:3000/art.js?913b8578eb54cde21abc07c994f6b29267232bc5:61:28)
    at http://localhost:3000/packages/blaze.js?a5c324925e5f6e800a4c618d71caf2848b53bf51:2880:16
    at http://localhost:3000/packages/blaze.js?a5c324925e5f6e800a4c618d71caf2848b53bf51:1651:16
    at http://localhost:3000/packages/blaze.js?a5c324925e5f6e800a4c618d71caf2848b53bf51:2928:66
    at Function.Template._withTemplateInstanceFunc (http://localhost:3000/packages/blaze.js?a5c324925e5f6e800a4c618d71caf2848b53bf51:3476:12)
    at http://localhost:3000/packages/blaze.js?a5c324925e5f6e800a4c618d71caf2848b53bf51:2927:27
    at Spacebars.call (http://localhost:3000/packages/spacebars.js?7bafbe05ec09b6bbb6a3b276537e4995ab298a2f:172:18)
    at Spacebars.mustacheImpl (http://localhost:3000/packages/spacebars.js?7bafbe05ec09b6bbb6a3b276537e4995ab298a2f:109:25)
    at Object.Spacebars.mustache (http://localhost:3000/packages/spacebars.js?7bafbe05ec09b6bbb6a3b276537e4995ab298a2f:113:39)
    at null._render (http://localhost:3000/template.art.js?30aa5e2d0b6d3de2f69b7341296ae51b8ce737ba:27:22)

The exception refers to this line of code:

sources.push(images[i].source);

How can this be fixed?

I suspect that you are not publishing and subscribing to the Projects collection. As you create the projects they temporarily exist on the client but are then removed. — Michel Floyd
– Michel Floyd, Commented Jul 21, 2015 at 20:21

GPicazo · Accepted Answer · 2015-07-21 19:43:53Z

1

Try:

sourceArray : function () {
      var images = Projects.find().fetch();

      var sources = [];
      for (var i = 0; i < images.length; i++) {
        sources.push(images[i].source);
      }
      return sources;

  }

If as you said, you defined images as a template helper property, you may need

this.images[i].source

answered Jul 21, 2015 at 19:43

GPicazo

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1 Comment

GPicazo Over a year ago

Not sure I understand what you mean.

David Weldon · Accepted Answer · 2015-07-21 23:09:43Z

1

Just redefine it in your helper. That's probably what you want to anyway so it will be reactive. Here's an implementation that should work:

sourceArray: function() {
  return _.pluck(Projects.find().fetch(), 'source');
}

edited Jul 21, 2015 at 23:09

answered Jul 21, 2015 at 19:44

David Weldon

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