readfeatures.go

package main

import (
	"database/sql"
	"time"
)

const querySQL = `
SELECT
   st_x(koordinate),
   st_y(koordinate),
   zeit,
   strom,
   round((st_distance_sphere(koordinate,ST_GeomFromText('POINT(8.3726 48.9992)', 4326))/1000)::numeric,1)  as dist,
   typ
FROM blitz.blitze
  where zeit between '2018-07-17 21:00' and '2018-07-17 22:00'
  and  round((st_distance_sphere(koordinate,ST_GeomFromText('POINT(8.3726 48.9992)', 4326))/1000)::numeric,1) < 10
  order by dist asc
`

type Feature struct {
	Type string `json:"type"`

	Geometry *map[string]interface{} `json:"geometry"`

	Properties *map[string]interface{} `json:"properties,omitempty"`
}

func getFeatures(db *sql.DB) ([]*Feature, error) {

	rows, err := db.Query(querySQL)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var features []*Feature

	for rows.Next() {
		var (
			coords [2]float64
			zeit   time.Time
			strom  float64
			dist   float64
			typ    int
		)

		if err := rows.Scan(
			&coords[0], &coords[1],
			&zeit,
			&strom,
			&dist,
			&typ,
		); err != nil {
			return nil, err
		}

		feature := &Feature{
			Type: "feature",
			Geometry: &map[string]interface{}{
				"type":        "Point",
				"coordinates": coords[:],
			},
			Properties: &map[string]interface{}{
				"zeit":  zeit.String(),
				"strom": strom,
				"dist":  dist,
				"typ":   typ,
			},
		}

		features = append(features, feature)
	}

	return features, rows.Err()
}