50 lines
1.2 KiB
Go
50 lines
1.2 KiB
Go
package db
|
|
|
|
import (
|
|
"context"
|
|
"fmt"
|
|
"time"
|
|
)
|
|
|
|
// Datum is a single measurement - it is more granular than a packet.
|
|
// the classic example is bms_measurement.current
|
|
type Datum struct {
|
|
Timestamp time.Time `db:"timestamp"`
|
|
Value any `db:"val"`
|
|
}
|
|
|
|
// GetValues queries the database for values in a given time range.
|
|
// A value is a specific data point. For example, bms_measurement.current
|
|
// would be a value.
|
|
func (tdb *TelemDb) GetValues(ctx context.Context, packetName, field string, start time.Time,
|
|
end time.Time) ([]Datum, error) {
|
|
// this fragment uses json_extract from sqlite to get a single
|
|
// nested value.
|
|
const SqlFrag = `
|
|
SELECT
|
|
datetime(ts /1000.0, 'unixepoch', 'subsec') as timestamp,
|
|
json_extract(data, '$.' || ?) as val
|
|
FROM bus_events WHERE name IS ? AND timestamp IS NOT NULL
|
|
`
|
|
fmt.Print(start, end, packetName, field)
|
|
|
|
rows, err := tdb.db.QueryxContext(ctx, SqlFrag, field, packetName, start, end)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer rows.Close()
|
|
data := make([]Datum, 0, 10)
|
|
for rows.Next() {
|
|
var d Datum
|
|
err = rows.StructScan(&d)
|
|
if err != nil {
|
|
fmt.Print(err)
|
|
return data, err
|
|
}
|
|
data = append(data, d)
|
|
}
|
|
fmt.Print(data)
|
|
|
|
return data, nil
|
|
}
|