68 lines
1.4 KiB
Go
68 lines
1.4 KiB
Go
package db
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import (
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"context"
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"fmt"
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"time"
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)
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// Modifier augments SQL strings.
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type Modifier interface {
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ModifyStatement(string) string
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}
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type LimitOffsetModifier struct {
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Limit int
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Offset int
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}
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// BusEventFilter is a filter for bus events.
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type BusEventFilter struct {
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Names []string
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TimerangeStart time.Time
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TimerangeEnd time.Time
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}
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// now we can optionally add a limit.
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// Datum is a single measurement - it is more granular than a packet.
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// the classic example is bms_measurement.current
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type Datum struct {
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Timestamp time.Time `db:"timestamp"`
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Value any `db:"val"`
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}
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// GetValues queries the database for values in a given time range.
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// A value is a specific data point. For example, bms_measurement.current
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// would be a value.
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func (tdb *TelemDb) GetValues(ctx context.Context, packetName, field string, start time.Time,
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end time.Time) ([]Datum, error) {
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// this fragment uses json_extract from sqlite to get a single
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// nested value.
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SqlFrag := `
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SELECT
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ts as timestamp,
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json_extract(data, '$.' || ?) as val
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FROM bus_events WHERE name IS ?
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`
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rows, err := tdb.db.QueryxContext(ctx, SqlFrag, field, packetName)
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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data := make([]Datum, 0, 10)
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for rows.Next() {
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var d Datum = Datum{}
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err = rows.StructScan(&d)
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if err != nil {
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fmt.Print(err)
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return data, err
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}
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data = append(data, d)
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}
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fmt.Print(rows.Err())
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return data, nil
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}
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