Instead of calculated item try dependent item. I think it should work.

No, unfortunately Dependent Item - Doesn't see "webscenario items"

is your regexp missing closing parenthesis, and incorrectly anchoring to the end of the string ?

No, it was a typo. Regex: ^.([0-9])+$
and I always check first with online regex validators.
Besides, regex alternative, Trim Left/Right, should have worked anyway.

To me, the logic in this case looks the following:

1)
Regular expression with capture group support and Trim functions - are Exactly made for stripping out the required part of Strings.
Regular expressions and Trim - are by idea designed for string manipulation.

2)
If these functions are available - then you should be able to use them. They should work.

3)
If pre-processing block is available then it should be working as its name says: PRE - means - before - means processing Before.
Before final evaluation against Numeric or Float data type.

4) Evaluation against Numeric or Float data type should be initiated only when required.

It it required:
1) before any MATH operation in "Calculated item" body ( last(ItemName) - this function is not a Math operation ! )
2) before any MATH operation in Pre-processing block ( Regex capture groups and Trim - are not Math operations ! )
3) and finally evaluation against numeric - should be At The END - just before actual item creation, so this makes possibility for zabbix users to fulfill Regex/Trim manipulations BEFORE -
to get actual needed numeric part from the string.

Here, I found a comment that confirms my thoughts:

In Ticket: ZBX-13230

https://support.zabbix.com/browse/ZBX-13230?focusedCommentId=255558&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-255558

From documentation: https://www.zabbix.com/documentation/3.4/manual/config/items/itemtypes/calculated

The correct syntax of a simple formula is:
func(<key>|<hostname:key>,<parameter1>,<parameter2>,...)
, Where:
func One of the functions supported in trigger expressions: last, min, max, avg, count, etc

now if we check functions link:
https://www.zabbix.com/documentation/3.4/manual/appendix/triggers/functions

we find this definition:
last (sec|#num,<time_shift>)
Supported value types: float, int, str, text, log

and at the bottom of page we see:
1) All functions return numeric values only (Whaat ??!). Comparison to strings is not supported, for example
P.S: if so, then Trigger functions would never work for any String item and .last() function.

This is confusing.
Looks like some things are messed up.

Let me do some explanation... First of all, I strongly recommend you read a beautiful piece of documentation describing operation of item preprocessing.

1) I agree, applying regexps and trimming numbers does not make much sense. Usually. But since Zabbix really lacks mathematical operations, regexp can save you someday.
2) They work, but they are applied to the end result of calculation.
3) Pre- means "before". Before saving the value into DB and putting it into triggers. But from another perspective it's postprocessing since it's done after data gathering (which in case of calculated items is formula calculation).
4) Not sure what you mean by that.

You completely miss the fact that there could be many items in calculated item formula and it would be strange to apply same preprocessing to all of them.

As I said, for your use case you should create a Dependent item. I know it is not possible at the moment, but maybe it's a bug. I'll try to figure out why such decision was made and will get back to you later. Stay tuned.

P.S: if so, then Trigger functions would never work for any String item and .last() function.

They only work if your Character, Text or Log item for some reasons stores numbers, see ZBX-10449.

"But from another perspective it's postprocessing"

That's it.
The name of this feature is confusing.

Pre - processing - is logically - apply some specific action, that happens over data - Before actual data processing.
Actual data processing is - Formula.

But this really is - Post-processing. - means - apply some specific action - AFTER we have acquired and made manipulations on data.

"You completely miss the fact that there could be many items in calculated item formula and it would be strange to apply same preprocessing to all of them."

I agree, this makes sense.

But this name "pre-processing" - is incorrect then.

what about last() function which in documentation said: supports - num, float, str, text types
and it fails because of string value in this Formula block.
however what it does - just gets the last value from the item - nothing else.
Its not a math function, not an avg, not min. max, not any calculation.

"Processing" is triggers, for all item types. Formula is a kind of "data gathering" for calculated items. "Preprocessing" means "before processing triggers". I hope this starts to make sense if you think of it this way.

this ZBX-10449 doesn't throw a light on this behavior.

as documentation says: Supported value types: float, int, str, text, log

why it then evaluates on numeric and fails?
this is a bug?

"I hope this starts to make sense if you think of it this way."
But this is a hack.

Because pre-processing of data - literally means - apply some changes - before actual data manipulation.
In triggers - you do not manipulate this data, you do not process it, as the data - remains unchanged.
Triggers, graphs - is a reaction or display of data.

I have worked in DSP (Digital Signal Processing) laboratory so I exactly understand the term of "processing"

and that " a beautiful piece of documentation "
was made, I suppose, exactly because "Preprocessing" in Zabbix Items - was (and possibly still is) - confusing for many people

Hello,

any updates on why "web monitoring" items are not available for "dependent items" ?
maybe developers just forgot about them

I've noticed this thing is controlled by an URL, which is popped when I press "select" dependent item.

http:/zabbix.server/popup.php?srctbl=items&srcfld1=itemid&dstfld1=master_itemid&dstfrm=itemForm&srcfld2=master_itemname&dstfld2=master_itemname&only_hostid=32&with_webitems=0&excludeids[]=

as you can see, the argument value "with_webitems=0" possibly is the key to how web items were hidden.

Yes, I confirm, that opening this url with with_webitems=1 - does Unhide web items.
However, the opened page has no reference to parent page, where it should pass selected item.
Maybe it is possible to modify somewhere in zabbix sources to make this parameter "with_webitems=1" or use CURL to create this item, but CURL would be hard and will take a lot of time, since there are needed many actions and clicks to add one item.

Discussed and the conclusion is that Web scenario items should be available for selection as master item.

I tried to trick the system, changed hardcoded setting with_webitems to "1", then changed passed HTTP headers, but Zabbix system designed smarter.
It said: I have no permissions to this object

Thanks, that may help some day to those who want to reflect web scenario failures or web page load speed on a graph, for example, or those who want to get and process error of web scenarios.

I just wanted to read Ink levels on a web page from HTTP enabled printer, which does not have SNMP. And create numeric items from obtained ink levels on a printer web page.
I can successfully strip out Ink Level, say 83% for example, in my web scenario, using these nice Regexp Capture groups. But there was no option to return acquired and processed value.
So I found out a way to return captured numeric value - through the web.error item.
But, it unfortunately appended it with text, so there are no way to turn it into new numeric item and by coincidence web items were not available in "dependent items".

(1) translation string changes

Strings added:

• Item "%1$s" has master item and cannot be copied.

Strings deleted:

• Item "%1$s" have master item and cannot be copied.

sasha RESOLVED

iivs Thanks! CLOSED

RESOLVED in svn://svn.zabbix.com/branches/dev/ZBX-13424

Hi,

Do you add these web items to be visible in "Calculated items" as well?
Because there was at least one numeric item, I guess site loading latency/speed, something, that could be used in Calculated items via last(web.test.time) or last(web.test.in)

Fixed in:

• pre-3.4.8rc1 r78686 (corrected ChangeLog r78687)
• pre-4.0.0alpha5 r78688

(5) [D] API documentation updated.

sasha CLOSED