Useful template examples relating to lights that I wish I had known earlier:

[petro]

@DefenestrateIT

The only code i have out write copied so far is Petro’s line ‘| rejectattr ( ‘attributes.entity_id’ , ‘defined’ )’, which i still don’t full understand how that works. But there’s a link to it at the bottom in ‘Counts the lights on’.

Read up on state objects

Last_updated State and last-changed in Lovelace

Ok, so this is where things get funky. You should familiarize yourself with home assistant state objects. This is what home assistant passes around when doing pretty much anything. These state objects contain 8 or so properties. Do not get these properties confused with the devices attributes. These properties are: Field Description state.state String representation of the current state of the entity. Example off. state.entity_id Entity ID. Format: .<object_id>. Example: light.…

@DefenestrateIT

rejectattr

Rejects items from a collection based on an attribute of the object (In python, they aren’t attributes, they are properties). Do not confuse the attr of rejectattr with attributes on the state object.

@DefenestrateIT

‘attributes.entity_id’

This is the attribute of the states object that you’re rejecting.

@DefenestrateIT

‘defined’ )

Does that attribute exist.

Putting it all together. You’re rejecting lights that have the entity_id attribute. Which specifically targets light groups as they are the only lights that have the entity_id attribute.