Dynamic icons, set over mqtt?

[zagi988]

Is there a way to set "text" field of a button to an icon, like "\uE40A"?
I'm trying using this configuration.yaml code but I get text displayed, not icon.

• obj: "p1b24"
  properties:
  "text": >
  {% if is_state('media_player.thinkcentre_ha', 'playing') %}
  \uE3E4
  {% else %}
  \uE40A
  {% endif %}

[zagi988]

Works like this:

• obj: "p1b24"
  properties:
  "text": >
  {% if is_state('media_player.thinkcentre_ha', 'playing') %}
  {{ "\uE3E4" }}
  {% else %}
  {{ "\uE40A" }}
  {% endif %}