Rrd4j presistence not working with itemsname included '_'

I discovered a problem with rrd4j presistense.

If I name the item
Number DoorSensor06Luminance
it is working, if I name it
Number DoorSensor06_Luminance
for better reading, it is not working.

mapdb presistence does not care about this character and works with both correctly.

Just to know it.

I played around a litte bit. And what I discovered before is wrong.

The problem ist the item naming bit in a different way:

This one works:
Number DoorSensor06_Luminance “Luminance [%d %%]” {channel=“zwave:device:15a7a49f3a6:node9:sensor_luminance”}

This one not:
Number DoorSensor06_Luminance “[%d %%]” {channel=“zwave:device:15a7a49f3a6:node9:sensor_luminance”}

It looks like the chart does not know how to name the chart because no name in available in the item definition.

Thats it.

to give the chart a hint with label does not help the chart

Chart item=DoorSensor06_Luminance label=“DoorSensor06Luminance” period=D refresh=30000 service=“rrd4j”

is working only if
Number DoorSensor06_Luminance “Luminance [%d %%]” {channel=“zwave:device:15a7a49f3a6:node9:sensor_luminance”}

and the label will be “Luminance” not “DoorSensor06Luminance” as given in the Chart definition

Chart Items do need unique labels for every item involved. For example, if you have a chart item

Group MyChart
Number MyItem1 "My Item 1 [%d %%]" (MyChart)
Number MyItem1 "My Item 2 [%d %%]" (MyChart)
Number MyItem1 "My Item 3 [%d %%]" (MyChart)
Number MyItem1 "My Item 4 [%d %%]" (MyChart)
Chart item=MyChart period=D refresh=30000 service="rrd4j"

this would draw 4 different lines in a Chart. But the Chart then needs 4 different labels for each line, for generating a caption.

In question of providing a label to the Chart item itself, this wouldn’t affect the caption inside the chart, but the chart itself (well, this label is hidden…)

So, you have to define unique labels for each item, together used in a chart, and this label has to be set in *.items file. The label can’t be null, because it would lead into a null string for caption.

my inital goal was to change z-wave config in item files as less as possible. Because if I change a zwave item, all values got lost. Every cosmetic around label and text should be done outside of this file.

My idea was:

Number DoorSensor06_Luminance “[%d %%]” {channel=“zwave:device:15a7a49f3a6:node9:sensor_luminance”}
No text in item, only format syntax. If I need a text I will put it in the site map

Text item=DoorSensor06_Luminance label=“Luminance”

But chart uses text from Item, if no text, chart crashes. This is why I thought to put wished chart label in the chart description. This is not working as you wrote.