services setAlias experiments

[gabor]

when you use query_type=metrics, and add the function setAlias($__zbx_host_name: abcd), this will work.
when you do the same for query_type=services, it does not work.

based on some investigation it seems it will not be easy to make it work for query_type=services.

for query_type=metrics this works, because this is executed as a backend-query, and that handler eventually reaches this line:

grafana-zabbix/src/datasource/datasource.ts

Line 214 in 62a292d

this.applyFrontendFunctions(resp, request);

,

and applyFrontendFunctions calls setAlias.

when query_type=services, it is not a backend query, so the same code is not called.
instead, we call

grafana-zabbix/src/datasource/datasource.ts

Line 488 in 62a292d

async queryITServiceData(target: ZabbixMetricsQuery, timeRange, request) {

, and that codepath does not call applyFrontendFunctions.

in this draft PR, i tried some quick hacks to make things work, you can see i added the applyFrontendFunctions call in datasource.ts.

this will cause setAlias to be called.

but that is not enough.
in setAlias, there is a main IF, which branches based on the field-count, if it's 2 or less, it goes into the first branch. we fall here, but the code looks for a field named Value, which it does not find. so it sets the frame-name and that's all.
my second hack adjusts this, where, if the value-field is not found, it lets the code continue. and this will finally apply the alias.

but that is not enough.
you see, the "happy path", when it works for query_type=metrics, works because of this line:

grafana-zabbix/src/datasource/dataProcessor.ts

Line 10 in 62a292d

alias = getTemplateSrv().replace(alias, valueField?.config?.custom?.scopedVars);

... it will use the dataframe field's valueField.config.custom.scopedVars, so that it has access to variables. this way, when you do setAlias($__zbx_host_name...), the value for zbx_host_name is found there (probably, i'm guessing 😁 ). but in our case, there is no such attribute, so while something like setAlias(abcd), will work, setAlias($__zbx_host_name) will not, because it's unable to find that variable's value.

[gabor]

this was only a test and demonstration, closing it now.