Use CoordinatorEntity when using the DataUpdateCoordinator

I recently had a user point out that one of my custom components that monitors a user’s Nintendo Wish List was using excessive data. He pointed out the drop in traffic to the domain that is used to search for games on sale in Europe when he disabled the integration as you can see below and in the header image.

I was a bit perplexed as the custom integration utilized Home Assistant’s DataUpdateCoordinator which drastically reduces network calls by fetching all of the data needed by the entities just once. The entities then use the data stored by the coordinator to update their state. The other way to do this is to have each entity (think 10 games on your wish list) and each one individually hits the api to see if it’s on sale. Since all the data comes from the same endpoint we only need to make that call once and the DataUpdateCoordinator helps us manage that.

One of the arguments that is passed to the DataUpdateCoordinator is a datetime.timedelta that specified how often it should update. I have this value configurable through the integration and defaulted to once an hour. After doing some debugging I saw thousands of updates were being made in the first few hours.

The TLDR is if you are using the DataUpdateCoordinator, your entities need to make sure that they return False for the should_poll property. By default this value is True when you sub-class the Entity or BinarySensorEntity. Without this, data will be fetched about every 30 seconds.

While I was investigating this issue I stumbled upon the CoordinatorEntity which was added at some point in the Fall of 2020. This class basically just takes care of defining a few common methods you would normally add to all of your Entity classes when you are using the DataUpdateCoordinator. It also explicitly sets the should_poll property to False which was the hint I needed to figure out why my integration was making so many network calls.

If you are interested in the details, the commit to switch to sub-classing the CoordinatorEntity can be found here. Hopefully this helps someone else out if they run into this issue with their custom component.