Fix v8 tableresult empty

[peishaofeng]

Overview

• auto-convert DataFrame query format to TimeSeries on Grafana v8.*
• fix prettier/eslint errors
• upgrade @grafana SDK to ~8.2.5

What this PR does / why we need it

To fix issue #227 Empty results in status map panel post grafana version upgrade from v7.4 to v8.1. #227

Special notes for your reviewer

1. auto-convert data format according Grafana version

on v7 keep existing data format, no conversion.

on v8 made changes below:

• listen on new event PanelEvents.dataFramesReceived for DataFrame format
• convert DataFrame to TimeSeries format with DataProcessor
• copy data_processor.ts from Grafana graph panel plugin with minor modification

${GRAFANA}/public/app/plugins/panel/graph/data_processor.ts

I have verified the same plugin package build on both Grafana v8.0.6 and v7.4.2, it works fine.

2. SDK 8.3.0 report fail

@grafana SDK 8.3.0 report error, so i use 8.2.5 instead

✖ PostCSS plugin postcss-discard-comments requires PostCSS 8.
Migration guide for end-users:
https://github.com/postcss/postcss/wiki/PostCSS-8-for-end-users
  Trace: Error: PostCSS plugin postcss-discard-comments requires PostCSS 8.
  Migration guide for end-users:
  https://github.com/postcss/postcss/wiki/PostCSS-8-for-end-users

Does this PR introduce a user-facing change?

NONE

[diafour]

Thank you for this PR! DataFrames support is a long-awaited feature.

I've got some findings about data frames and Grafana versions (not precise, sorry):

1. Panels plugins with dataFrames are supported since Grafana 6.7.
2. @grafana/data module appears in plugins with migration to PanelEvents.
3. Adding import @grafana/data make plugin not working in Grafana <=6.3. It is not possible to check if module is not injected and change plugin behavior for that older versions.

How these facts affect your PR?

1. Update README.md: set minimum supported version to Grafana 6.7.
2. V8 detection is not needed, use data frames for data handling. Set this.useDataFrames = true and remove onDataReceived.
3. Import PanelEvents and CoreEvents from @grafana/data, no need to fallback to string-based events. Remove all Polygrafill hackery: fallbackToStringEvents, ./util/grafana/events, etc.

Do you have time to make these changes?

[peishaofeng]

Yes, I'd like to be of help to make this panel plugin better.
Also need to prepare both v6 & v7 environment to verify modification, next week should have spare time to do further optimization as you mentioned above.

[peishaofeng]

submit changes according your suggestion, the same plugin build are verified on v6.7.1/v7.4.2/v8.2.5

1. convert DataFrame to series list

• useDataFrames for version > v7.0
• add DataProcessor to convert query result in type of DataFrame to series list(TimeSeries2)
• register new data events handler dataFramesReceived & dataSnapshotLoad for DataFrame type
• remove prefixed column name in series tag name in v8.0+, keep compatible with v7.x series name

2. remove string-based events polyfill

• replace all self-defined PanelEvents (refresh/render/dataReceived etc) with @grafana/data PanelEvents
• remove fallbackToStringEvents
• prefix self-defined event names(graphHover and graphHoverClear) with statusmap

Grafana v6.* has built-in graphHover and graphHoverClear defined which cause event name conflict with self-defined events.

3. move renderComplete to utils/grafana/events/events.ts

• collect all self-defined events in utils/grafana/events/events.ts

4. fix prettier warnings

• fix arrowParens warning

5. README.md

• Supported Grafana versions:
  • 6.7+ to 8.2+
  • prior 6.7 will cause plugin load fail (no support or incompatible @grafana/data and @grafana/runtime package)

6. plugin.json

  "dependencies": {
    "grafanaDependency": ">=6.7.0",
    "grafanaVersion": "6.7+",
    "plugins": [ ]
  }

[diafour]

OK, my eyes see no critical issues. I change README to something more user-friendly. I want to run some tests on different versions before merging.

[diafour]

Grafana 6.7 doesn't work if plugin sets this.useDataFrames = true?

[peishaofeng]

on v6.7 although MetricsPanelCtrl has member useDataFrames defined, but PanelEvents.dataFramesReceived still not emerge, register this event will raise exception, neither onDataFramesReceived nor onDataReceived can receive query result, I guess DataFrame is formally released from v7.0?