task-list.html

<link rel="import" href="components/polymer/polymer.html">
<link rel="import" href="components/core-ajax/core-ajax.html">
<link rel="import" href="task-box.html">

<polymer-element name="task-list">
  <template>
    <core-ajax id="ajax"
      auto
      url="all/"
      on-core-response="{{tasksLoaded}}"
      handleAs="json">
    </core-ajax>

    <div layout vertical center>

      <template repeat="{{task in tasks}}">
        <task-box done="{{task.done}}" dataid="{{task.id}}" assigned="{{task.assigned}}">{{task.description}}</task-box>
      </template>
      
    </div>
  </template>
  <script>
    Polymer({
      tasks: [],
      tasksLoaded: function () {
        this.tasks = this.$.ajax.response.slice(0)
      },
      addTask: function (task) {
        // overrides properties from from in into
        function extend(into, from) {
          for (var prop in from)
            into[prop] = from[prop]
        } 

        var std = {
          id: -1,
          done: false,
          description: '',
          assigned: null
        }
        
        extend(std, task)
        this.tasks.push(task)

        return task
      }
    })
  </script>
</polymer-element>