Set unit metadata & state description pattern when creating UoM Item

[florian-h05]

Related to openhab/openhab-core#3481.
Closes #2108.

• Ensures that the internal unit is set when an Item is created, so that in case the system unit changes (i.e. measurement system changes) persisted data does not get corrupted.
  By default, the unit metadata is set to the system default unit, however the user can easily change that on Item creation.

  The unit can also be changed later as it is just normal metadata, however this can corrupt persisted data.

• Adds the ability to set state description pattern when creating a UoM Item.

• Shows the group type for groups, e.g. Group (Number:Temperature) instead of just the Item type.

This applies to both the Items and the model page.

[florian-h05]

This was actually discussed somewhere, but I cannot find this discussion now.
Maybe @J-N-K finds that discussion?

[relativeci]

Job #1218: Bundle Size — 15.8MiB (+0.23%).

16c6c02(current) vs b7270d2 main#1158(baseline)

Warning

Bundle contains 16 duplicate packages – View duplicate packages

Warning

Bundle introduced 13 new packages: @jsep-plugin/regex, @jsep-plugin/arrow, @jsep-plugin/object and 10 more – View changed packages

Bundle metrics   10 changes 5 regressions 1 improvement

	Current Job #1218	Baseline Job #1158
Initial JS	1.85MiB(+11%)	1.67MiB
Initial CSS	608.95KiB(+0.01%)	608.89KiB
Cache Invalidation	93.81%	93.95%
Chunks	217(-0.91%)	219
Assets	683(-0.87%)	689
Modules	2987(+75.71%)	1700
Duplicate Modules	173(+92.22%)	90
Duplicate Code	1.61%(-17.44%)	1.95%
Packages	152(+10.14%)	138
Duplicate Packages	16(+6.67%)	15

Bundle size by type   3 changes 3 regressions

	Current Job #1218	Baseline Job #1158
JS	9.28MiB (+0.28%)	9.25MiB
Other	4.74MiB (+0.21%)	4.73MiB
CSS	860.19KiB (+0.08%)	859.49KiB
Fonts	526.1KiB	526.1KiB
Media	295.6KiB	295.6KiB
IMG	140.74KiB	140.74KiB
HTML	1.23KiB	1.23KiB

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View job #1218 report View florian-h05:item-fix-unit branch activity

[J-N-K]

This has been discussed several times. I'm not sure if fixing the unit is a good idea, while I agree that fixing the dimension is. The difference is: if you create an item, you have an idea what you want to use it for. This fixes the dimension, but not necessarily the unit.

IMO the unit should be editable, but there should be a warning that this might be a bad idea when persistence is involved.

[florian-h05]

IMO the unit should be editable, but there should be a warning that this might be a bad idea when persistence is involved.

The unit metadata is still editable through metadata edit, where a big orange warning is shown that this can corrupt persisted data. This PR only sets the unit metadata to the system default when creating an Item, so that there is unit metadata.

This is how it looks when creating an Item:

And this is how it looks when you want to change unit metadata later:

[rkoshak]

Does it make sense to merge this with #2108? Those are other places where Items are created and giving the users the option to set the unit before the Item is created right there in those respective forms (i.e. Model and add equipment to model) seems like more of the same as what's being implemented here.

[ghys]

This is how it looks when creating an Item:

I'm sorry to say it, but this description is absolutely preposterous; it's 4 lines long which is probably 2 too many and seriously:

All processed values are internally normalized to the specified unit. The normalized value is used to propagate the value to external integrations (e.g. persistence, REST API, WebSocket) so these values will always have the specified unit and scale.

You couldn't be as cryptic and obscure if you tried.

[florian-h05]

@ghys I have updated the description, I am open for suggestions!

@rkoshak I have tried to address #2108, please have a look at the PR description.

[spacemanspiff2007]

How about:

"Used internally, for persistence and external systems. It is independent from the state visualization in the GUI which is defined through the state description".

[rkoshak]

I'm not good at translating this code to what it will look like but based on "This applies to both the Items and the model page" it's not clear this also impacts "create equipment from thing" and "add points to model".

If I missed that I'd say it looks good. If It didn't then that's an important place to make suer we can set the unit too.

[florian-h05]

I'm not good at translating this code to what it will look like but based on "This applies to both the Items and the model page" it's not clear this also impacts "create equipment from thing" and "add points to model".

Those fields were displayed on both pages, but not pre-filled. I have fixed this.

"Used internally, for persistence and external systems. It is independent from the state visualization in the GUI which is defined through the state description".

Thanks for the suggestion!

[florian-h05]

@J-N-K @spacemanspiff2007 @rkoshak:
Should this PR be merged in the current state or is there anything left to be changed?

[rkoshak]

Based on my understanding the unit can be set by the end user in all the places and ways an Item can be created in MainUI so I'm happy to merge it.

[florian-h05]

@ghys Can you please review?

[ghys]

Yep sorry I had this one on the backburner for some time.
Let's say I'm not happy with the added complexity but I'm happy with the solution and implementation.

A big thank you for the work involved!