javascript - Polymer + Firebase (Polymerfire): Cannot read property 'push' of undefined': 'this.$.query.ref.push(...)'

Question

I'm following a Polymer + Firebase tutorial video using the Polymer App Tool Kit (initiated with the polymer CLI).

When I try to push data to a Firebase collection, I get the following error:

Cannot read property 'push' of undefined'

Here's my code (firebase app is initiated in my-app.html with name "firebase-app"):

<dom-module id="add-model">
    <!-- Defines the element's style and local DOM -->
    <template>
        <firebase-auth user="{{user}}" app-name="firebase-app"></firebase-auth>
        <firebase-query
                app-name="firebase-app"
                id="query"
                path="/users/[[user.uid]]/models"
                data="{{model}}">
        </firebase-query>
        <paper-input id="modelName" label="Model Name" "></paper-input>
        <paper-button class="create" id="create" on-tap="create" raised>Create</paper-button>
    </template>
    <!-- Creates the element's prototype and registers it -->
    <script>
        Polymer({
            is: 'add-model',
            properties: {
                data: {
                    type: Object
                }
            },
            create: function() {
               this.$.query.ref.push({
                   name: this.$.modelName.value
                });
            }
        });
    </script>
</dom-module>

Answer 1

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