Group objects in collection with Meteor

Question

I have a collection with fields type and number .

Right now I'm printing docs in the collection with

{{#each myRows}}
  <tr>
    <td>{{type}}</td>
    <td>{{number}}</td>
  </tr>
{{/each}}

Many rows has the same type value so I want to 'group' rows by type . How can I obtain this? I need something like

{{#types}}
  <tr>
    <th>{{type}}</th>
  </tr>
  {{#each numbersInType}}
  <tr>
    <td>{{type}}</th>
  </tr>
  {{/each}}
{{/each}}

Answer 1

Give something like this a try:

Template.myTemplate.helpers({
  types: function() {
    // fetch your rows somehow
    var rows = Collection.find().fetch();

    // hash of type data
    var types = {};

    _.each(rows, function(row) {
      var type = row.type

      // initialize each type in the hash if it isn't defined
      if (types[type] == null)
        types[type] = {type: type, numbers: []};

      // add the numbers to the array for this type
      types[type].numbers.push(row.number);
    });

    // the values of the has contain an array of properly formed data
    return _.values(types);
  }
});

The result of the helper will look like this:

[ { type: 'a', numbers: [ 1, 2, 3 ] },
  { type: 'b', numbers: [ 10, 11, 12 ] },
  { type: 'c', numbers: [ 100 ] } ]

Here's a sample template fragment:

{{#each types}}
  <tr>
    <th>{{type}}</th>
  </tr>
  {{#each numbers}}
    <tr>
      <td>{{this}}</th>
    </tr>
  {{/each}}
{{/each}}