Crash when iterating table with nil data returned?

[srclosson]

For some reason, the following scenario causes a crash:

Data returned from influxdb 2.0

	csvRows := []string{
		`#group,false,false,true,true,true,true,true,true,false,false`,
		`#datatype,string,long,dateTime:RFC3339,dateTime:RFC3339,string,string,string,string,double,dateTime:RFC3339`,
		`#default,mean,,,,,,,,,`,
		`,result,table,_start,_stop,_field,_measurement,cpu,host,_value,_time`,
		`,,0,2020-04-30T19:58:15.018029201Z,2020-04-30T20:58:15.018029201Z,usage_guest,cpu,cpu-total,084469dbdc49,,2020-04-30T19:58:20Z`,
		`,,0,2020-04-30T19:58:15.018029201Z,2020-04-30T20:58:15.018029201Z,usage_guest,cpu,cpu-total,084469dbdc49,0,2020-04-30T19:58:30Z`,
		`,,0,2020-04-30T19:58:15.018029201Z,2020-04-30T20:58:15.018029201Z,usage_guest,cpu,cpu-total,084469dbdc49,0,2020-04-30T19:58:40Z`,
		`,,0,2020-04-30T19:58:15.018029201Z,2020-04-30T20:58:15.018029201Z,usage_guest,cpu,cpu-total,084469dbdc49,0,2020-04-30T19:58:50Z`,
		`,,0,2020-04-30T19:58:15.018029201Z,2020-04-30T20:58:15.018029201Z,usage_guest,cpu,cpu-total,084469dbdc49,0,2020-04-30T19:59:00Z`,
	}

To reproduce, simply call
dr := ExecuteQuery(ctx, models.QueryModel{}, runner)

With the csv returned above and the error looks like this:

anic(0xbcd080, 0x134a4b0)
        /go1.14.2/src/runtime/panic.go:969 +0x166
github.com/influxdata/influxdb-client-go.(*FluxTableMetadata).Column(...)
        /go1.14.2/global/pkg/mod/github.com/influxdata/[email protected]/table.go:59
github.com/influxdata/influxdb-client-go.(*QueryTableResult).Next(0xc000246af0, 0xd15d00)
        /go1.14.2/global/pkg/mod/github.com/influxdata/[email protected]/query.go:307 +0x851

I've not looked into it with more detail, but I suspect it has something to do with the face that in the first line of data the value is or empty?

Let me know

[vlastahajek]

@srclosson, such crash has been already fixed in the master with 6ac10dcc.
The flux result parser currently requires the datatype annotation as the first annotation row, and the Query method asks for it.
How did you manage to get such a result?
Do you query on your own and manually use QueryTableResult for parsing?
If yes, just make sure the datatype annotation is the first among annotations

[srclosson]

That did fix one problem, but there is another. The data was a query returned from influxdb 2.0. Notice the first line, the value column has no value. I expect this is because we used a grouping, and the first value was nil.

The query looks like this:

from(bucket: "grafana")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["_measurement"] == "cpu")
  |> aggregateWindow(every: v.windowPeriod, fn: mean)
  |> yield(name: "mean")

The error I get now is the strconv.ParseFloat failed.

Ideas?

[vlastahajek]

It's a bug. Unfortunately, empty values are not yet supported. You can work around this using the fill function in Flux

[vlastahajek]

You can now try version in the master, where this is fixed.

[srclosson]

Will try it out.

[srclosson]

Confrimed @vlastahajek. Thank-you!

[vlastahajek]

Just to let you know, that custom order of annotations is now supported since #134. Only the datatype annotation is required.