Object Model / API Description

[rlkoshak (Rich Koshak)]

@David_Solbach

How would I know the properties of a Homematic Rollershutter?

ALL Rollershutter Items have the same properties. One of the main purposes of Items is to model your home automation independent of the devices and technologies in use. A Homatic Rollershutter Item is identical to a Zwave Rollershutter Item.

@Bruce_Osborne

You can create an item manually & then “GET” it through the API to figure that out

I’m not sure that actually answers the OP’s question. I think he asking what methods are available on the Rollershutter Item which would not be reflected in the REST API.

@David_Solbach

But how would I know the exact property name?

All Items have a standard set of functions/properties you can call from Rules. See Rules | openHAB for how to specifically access, update, command and use Item’s states in a Rule.

There are other methods available to pull historical data from persistence, check/change Group membership, access members for a Group Item, and the like. They are all in the docs.

@David_Solbach

Or even the language syntax. Is it Java Script? confused

It is a custom Domain Specific Language based on Xtend. You can find info about the syntax here and here.

You appear to be a coder. You might be happier using JSR223 and coding Rules in Jython, JavaScript (Nashorn) or Groovy. Here is the version of your Rule in Jython using the Helper Library.

from core.rules import rule
from core.triggers import when

@rule("Luke zu bei Regen")
@when("Item Rain received update")
def luke(event):
    log.info("Rule triggered {}".format(items["Rain"]))
    if items["Rain"] > DecimalType(0.06): events.sendCommand("Shutter_Bedroom", 0)

@David_Solbach

But what about the description of (for example) the Number or the Rollershutter Object?

For the purposes of Rules, the only difference is the type of MyItem.state. For a Number the type will be DecimalType (which itself is of type Number). Rollershutter is of type PercentType (also of type Number). Both Items have the same properties and methods.

See Items | openHAB for further details.

The easiest way to get the full list of methods available on any Object in Rules DSL is to use VSCode with the openHAB extension. Then you can type MyItem. and a dialog with all the valid completions will pop up. Beyond that you can look at the source code for GenericItem. For the most part you will only care about state, sendCommand and postUpdate.

@David_Solbach

Okay. Now I know how to see the properties of an Item. Seems the “sendCommand()” explicitly sets the state property.

See Rules | openHAB. There are very important distinctions between sendCommand and postUpdate you need to understand.

@David_Solbach

Where would I look for the documentation of a collection / list that contains all items?

There is no such thing in Rules DSL. You can get a dict of all Items and their current state in Jython Rules, called items.

@David_Solbach

Next: I want to cycle through all items of group “gFritzBox” to check if the Contacts are “online” or “offline”. So instead of using the item names in the rule I’d like to select the items based on their group…

Explain more what you are after because there are lots of ways to do this depending on what you are after, some of which don’t even require a Rule.

Get a count of all the OPEN contacts:

Group:Number gFritzBox

Set gFritxBox to OPEN if any member of the Group is OPEN

Group:Contact:OR(OPEN, CLOSED) gFritzBox

Trigger a Rule when any member of gFritzBox changes to OPEN

rule "something opened!"
when
    Member of gFritzBox changed to OPEN
then
    // do something
end

Jython version:

from core.rules import rule
from core.triggers import when

@rule("something opened")
@when("Member of gFritzBox changed to OPEN")
def opened(event):
    # do something

Do something with all OPEN members of gFritzBox when one of them changes to OPEN

rule "something opened!"
when
    Member of gFritzBox changed to OPEN
then
    gFritzBox.members.filter[ i | i.state == OPEN ].forEach[ i |
        // do something on each member that is OPEN
    ]
end

See Design Pattern: Working with Groups in Rules for further details.

from core.rules import rule
from core.triggers import when

@rule("something opened!")
@when("Member of gFritzBox changed to OPEN")
def opened(event):
    for i in filter(lambda i: i.state == OPEN, ir.getItem("gFritzBox").members):
        # do something

Check the group membership of an Item

    if(MyItem.getGroupNames.contains("MyGroup"){

Jython:

    if "MyGroup" in ir.getItem("MyItem").getGroupNames():