Even better than the link @hmerk posted, Battery Level Status (installable from the Marketplace) can solve:
- “Show me a list of all items that run on battery and indicate a ‘low battery’ status if there is one”
- “1) Show me somewhere in the pages a single indicator if at least one item has this problem”
-" 2) also a full blown list where I can lookup which of the items needs a battery replacement."
and Threshold Alert [3.2.0;3.4.9) (also installable from the Marketplace) can solve
- “please report the result from 1) at least once daily into a chat channel at a given time”.”
The only part you’d have to implement is the “into a chat channel” part.
If you don’t just install and use these, they can at least serve as a pretty close example.
That’s not how it works. The UI shows the states of Items. All the information you want therefore is represented as Items. So the only schedule that is needed is to look at the current state of the Items on a schedule and send the chat when necessary. That’s 100% rules. Everything else is just choosing how to represent the current states of the Items which is 100% UI.
Items are a currency of the realm. They are the main abstraction layer in OH. Everything you do in openHAB is going to be using and manipulating Items.
To my knowledge there is no table widget. But you can use a List widget and show different rows and you can configure each row to show different information in “cloumns”. This is best done using the repeater element.
As you can see in the Battery Widget I posted above, if all the batteries are above the threshold it just shows the header with the minimum battery level. Only if one or more batteries are below the threshold are they shown below, one row per battery. So you have one widget which does both jobs.
But if you really need a separate widget, just create a regular old label widget that shows the minimum battery level. Or use visibility to hide an element unless the min batter level is below a threshold. Or create a rule to update a Switch Item to ON when the min battery level is below a certain threshold.