Prepare for storing device data in database

- create device id from mqtt topic
- implement method for storing device in database

Still todo:
- extract other data (e.g. MAC, SN) from monitoring object
- find a way in mqtt to use global env

models/db.go

@@ -8,6 +8,7 @@ import (
 
 type Datastore interface {
 	AllDevices() ([]*Device, error)
+	InsertDevice(*Device) error
 }
 
 type DB struct {

models/devices.go

@@ -1,36 +1,41 @@
 package models
 
 type Device struct {
-	ID string
-	MAC string
-	SN string
+	ID      string
+	MAC     string
+	SN      string
 	LastMsg string
 }
 
-
-
-
-
 func (db *DB) AllDevices() ([]*Device, error) {
-    rows, err := db.Query("SELECT * FROM devices")
-    if err != nil {
-        return nil, err
-    }
-    defer rows.Close()
+	rows, err := db.Query("SELECT * FROM devices")
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
 
-    devices := make([]*Device, 0)
-    for rows.Next() {
-        device := new(Device)
-        err := rows.Scan(&device.ID, &device.MAC, &device.SN, &device.LastMsg)
-        if err != nil {
-            return nil, err
-        }
-        devices = append(devices, device)
-    }
-    if err = rows.Err(); err != nil {
-        return nil, err
-    }
-    return devices, nil
+	devices := make([]*Device, 0)
+	for rows.Next() {
+		device := new(Device)
+		err := rows.Scan(&device.ID, &device.MAC, &device.SN, &device.LastMsg)
+		if err != nil {
+			return nil, err
+		}
+		devices = append(devices, device)
+	}
+	if err = rows.Err(); err != nil {
+		return nil, err
+	}
+	return devices, nil
 }
 
+func (db *DB) InsertDevice(device *Device) error {
+	sqlStmt := `INSERT OR REPLACE INTO table (id, mac, sn, lastMsg)
+                VALUES($1, $2, $3, $4);`
+	_, err := db.Exec(sqlStmt, device.ID, device.MAC, device.SN, device.LastMsg)
+	if err != nil {
+		return err
+	}
 
+	return err
+}