tempestas

commit 0d6c3e32ae774ba0a91ae1a76df13f0b280f03a7
parent 643d13b91062e6bbd86bf9b93adffdfb47350b1b
Author: Chris Bracken <chris@bracken.jp>
Date:   Thu, 11 Nov 2021 16:45:41 -0800

Add JSON API to query readings

Adds an HTTP GET endpoint at /sensor/reading/ to query readings from
storage.

Diffstat:
M
http/http.go
 | 
18
++++++++++++++++++
M
storage/storage.go
 | 
39
++++++++++++++++++++++++++++++++++-----

2 files changed, 52 insertions(+), 5 deletions(-)
diff --git a/http/http.go b/http/http.go
@@ -25,6 +25,7 @@ func CreateServer(ds storage.DataStore) *HttpServer {
 func (s HttpServer) ListenAndServe(addr string) error {
 	mux := goji.NewMux()
 	mux.HandleFunc(pat.Post("/sensor/airrohr/"), s.PostAirrohr)
+	mux.HandleFunc(pat.Get("/sensor/reading/"), s.QueryReadings)
 	return http.ListenAndServe(addr, mux)
 }
 
@@ -52,6 +53,23 @@ func (s HttpServer) PostAirrohr(w http.ResponseWriter, r *http.Request) {
 	errorResponse(w, "Success", http.StatusOK)
 }
 
+func (s HttpServer) QueryReadings(w http.ResponseWriter, r *http.Request) {
+	start := time.Now().Add(time.Hour * -24)
+	end := time.Now()
+	// TODO: extract start/end from r.URL.Query() with a default if not present.
+	readings, err := s.ds.QueryReadings(start, end)
+	if err != nil {
+		fmt.Println("Error: failed to query sensor data: " + err.Error())
+		errorResponse(w, "Bad Request. "+err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	jsonResp, _ := json.Marshal(readings)
+	w.Write(jsonResp)
+}
+
 func errorResponse(w http.ResponseWriter, message string, httpStatusCode int) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(httpStatusCode)
diff --git a/storage/storage.go b/storage/storage.go
@@ -11,19 +11,22 @@ const (
 	INSERT_READING = "INSERT INTO " +
 		"sensor_data(sensor_id, sw_version, reading_time, reading_type, reading_value) " +
 		"VALUES($1, $2, $3, $4, $5)"
+	QUERY_READINGS = "SELECT sensor_id, sw_version, reading_time, reading_type, reading_value " +
+		"FROM sensor_data WHERE reading_time >= $1 AND reading_time < $2"
 )
 
 type Reading struct {
-	SensorId        string
-	SoftwareVersion string
-	Time            time.Time
-	Type            string
-	Value           float64
+	SensorId        string    `json:"sensor_id"`
+	SoftwareVersion string    `json:"sw_version"`
+	Time            time.Time `json:"time",string`
+	Type            string    `json:"type"`
+	Value           float64   `json:"value"`
 }
 
 type DataStore interface {
 	Close()
 	StoreReading(r *Reading) error
+	QueryReadings(start time.Time, end time.Time) ([]Reading, error)
 }
 
 type PostgresDataStore struct {
@@ -59,6 +62,27 @@ func (s *PostgresDataStore) StoreReading(r *Reading) error {
 	return err
 }
 
+func (s *PostgresDataStore) QueryReadings(start time.Time, end time.Time) ([]Reading, error) {
+	rows, err := s.db.Query(QUERY_READINGS, start, end)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var readings []Reading
+	for rows.Next() {
+		var r Reading
+		if err := rows.Scan(&r.SensorId, &r.SoftwareVersion, &r.Time, &r.Type, &r.Value); err != nil {
+			return readings, err
+		}
+		readings = append(readings, r)
+	}
+	if err = rows.Err(); err != nil {
+		return readings, err
+	}
+	return readings, nil
+}
+
 type NullDataStore struct {
 }
 
@@ -72,3 +96,8 @@ func (s *NullDataStore) Close() {
 func (s *NullDataStore) StoreReading(r *Reading) error {
 	return nil
 }
+
+func (s *NullDataStore) QueryReadings(start time.Time, end time.Time) ([]Reading, error) {
+	var readings []Reading
+	return readings, nil
+}