Use templateSrv to interpolate timeFrom and timeTo variables.

[carvid]

I realized that timeFrom and timeTo variables can be used to access the overridden time range values at the panel level (Query Options). Those variables were interpolated using a regex instead of using templateSrv, thus preventing custom date formats to be used. With this change, it's now possible to specify a custom date format for timeFrom and timeTo variables if running on Grafana >= v7.2. For example:

query {
  data:submissions(
    where: {
      submitTime: {_gte: "${timeFrom:date}", _lte: "${timeTo:date}"},
    }
  ) {
    Time:submitTime
  }
}

[retrodaredevil]

I meant to make this PR a long time ago but I never got around to it. It looks good to me, we might consider removing timeFrom and timeTo altogether unless we want to keep backwards compatibility with older queries since we just use __from and __to now.

But this is definitely much better than what we had before.

[retzkek]

Date formats are fully supported using the builtin $__from and $__to variables, which are the recommended/documented variables to use now. I do think we should keep the legacy variables for backwards comparability, but I don't think we should add new features to them.

[carvid]

@retrodaredevil and @retzkek I might getting this wrong since I'm not a Grafana expert, but Isn't timeFrom and timeTo meant to access the overridden time range from the panel's "Query Options"?. I'm asking that because the builtin $__from and $__to always return the dashboard's time range.

[retzkek]

isn't timeFrom and timeTo meant to access the overridden time range from the panel's "Query Options"?.

No, they were just internal variables, from before the global builtins were added in Grafana 7.

the builtin $__from and $__to always return the dashboard's time range.

It looks like that's a bug grafana/grafana#20147

[carvid]

@retzkek thanks for the clarifying that. It seems that bug is there since Grafana v6.4.3. Other datasource plugins provide a different ways to access the time range so I guess that's the reason the bug is not fixed yet (e.g. MySQL and Postgres datasource provide __timeFilter, __timeFrom and __timeTo among other macros).

For now, I guess timeFrom and timeTo are the only workaround to get the panel's relative time for this plugin.

[retzkek]

I've tested this, sorry for the delay. It seems to work OK, although unfortunately the date format options that are provided for __from and __to don't seem to work, but the behavior doesn't change from what we had before, so 🤷. Presumably this is some limitation of templateSrv, but documentation here is scarce.

[retzkek]

LGMT. Thanks for contributing!