Polymer if-template with filter: filter not updating

StackOverflow https://stackoverflow.com/questions/23659300

Question

I am using an if-template to show or hide items in a list, within a Polymer-element. My template is based on a list of values, and filtered using a reference list.

Updating the list of values yields the desired effect. However, changing the filter reference list (here removing one element) does not yield an update of the template.

<!DOCTYPE html>
<html>
<head>
<script src="//cdnjs.cloudflare.com/ajax/libs/polymer/0.2.3/platform.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/polymer/0.2.3/polymer.js"></script>
  <meta charset="utf-8">
  <title>JS Bin</title>
</head>
<body>
  <test-component></test-component>
</body>
</html>

<polymer-element name='test-component' attributes='itemlist filterlist'>
  <template>
    <style>
    </style>
    <table id='table'>
      <tr template repeat="{{item in itemlist}}">
        <template if="{{item | applyFilter(filterlist)}}">
          <td>test</td>
        </template>
      </tr>
    </table>
    <input type='button' value='remove 1 element' on-click={{clicked}}></input>
    <div id='msg'></div>  
  </template>
  <script>
    Polymer('test-component', {
      itemlist: [1,2,3],
      filterlist: [1,2],
      applyFilter: function(item, filterlist) {
        var test = false;
        if (filterlist) {
          filterlist.forEach(function(filteritem) {
            test = test || ((new RegExp(filteritem)).test(item));
          });
        }
        return test;
      },
  clicked: function() {
    this.$.msg.innerHTML = 'Filter list was ' + this.filterlist;
    this.filterlist.splice(1,1);
    this.$.msg.innerHTML += ', now it\'s ' + this.filterlist;
  }
});

See http://jsbin.com/vuvikare/4/edit?html,output for runnable code.

Is there a way to trigger this update (for example using filterChanged observer)?

Thanks

Was it helpful?

Solution

This is very much a hack, but I got it to work by adding this method:

filterlistChanged: function() {
  Array.prototype.forEach.call(this.$.table.querySelectorAll('template[if]'), function(t) {
    t.iterator_.updateIteratedValue();
  });
},

Basically, it finds all the inner template elements in the table and forces them to update (using a private method).

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