What is the best way to retrieve multiple entities in single custom UI state card?

Development
1

I am trying to use multiple entities in a custom google chart state card. However, I suck at Polymer.
I’ve read a bit, but I simply don’t get it. Probably I am missing something small.
Starting from the standard example below, how could I retrieve and use the state or attribute of a secondary entity (or more) in the same state card/script (e.g. calculating something inside the script - the average brightness of two light bulbs)?
@andrey has a bunch of examples in his CustomUI git, but they are quite complex and I fail to understand.
Thank you in advance.

homeassistant:
  customize:
    light.bedroom:
      custom_ui_state_card: state-card-my-custom-light

frontend:
  extra_html_url:
    - /local/custom_ui/state-card-my-custom-light.html

<dom-module id='state-card-my-custom-light'>
  <template>
    <style>

    </style>
    <textarea>[[_toStr(StateObj)]]</textarea>
  </template>
</dom-module>

<script>
class StateCardMyCustomLight extends Polymer.Element {
  static get is() { return 'state-card-my-custom-light'; }
  
  static get properties() {
    return {
      // Home Assistant object
      hass: Object,
      // inDialog is true if shown as more-info-card
      inDialog: {
        type: Boolean,
        value: false,
      },
      // includes state, config and more information of the entity
      stateObj: Object,
    };
  }

  _toStr(obj) {
    return JSON.stringify(obj);
  }
}
customElements.define(StateCardMyCustomLight.is, StateCardMyCustomLight);
</script>
3

@eddi89 Thanks for the reply. I tried discord but I didn’t get a reply. Would you happen to have an example with the hass.states?

5

Thanks a lot. I completely forgot to stringify it. :frowning:
I have what I need.