first handler writing to database

src/udi/database/abstract_database.go

@@ -3,15 +3,20 @@ package database
 import "time"
 import "gorm.io/gorm"
 
+
+type VariableType struct {
+  Label string `json:"label"`
+  Variable string `json:"variable"`
+  Unit string `json:"unit"`
+  Value interface{} `json:"value,omitempty"`
+}
+
 type Measurement struct {
   Time time.Time `gorm:"not null;primary_key"`
   Application string `gorm:"not null"`
-  SensorType string `gorm:"not null"`
-  Sensor string `gorm:"not null"`
-  Variable string `gorm:"not null"`
-  Unit string
-  Value float32 `gorm:"not null"`
+  Device string
   Attributes map[string]string `gorm:"serializer:json;type:jsonb"`
+  Values map[string]VariableType `gorm:"serializer:json;type:jsonb"`
 }
 
 type Application struct {
@@ -20,21 +25,21 @@ type Application struct {
   Attributes map[string]string `gorm:"serializer:json;type:jsonb"`
 }
 
-type SensorType struct {
+
+type DeviceType struct {
   gorm.Model
   Label string `gorm:"not null"`
-  Variable string `gorm:"not null"`
-  Unit string
+  ModelIdentifier string
   Attributes map[string]string `gorm:"serializer:json;type:jsonb"`
 }
 
-type Sensor struct {
+type Device struct {
   gorm.Model
   Label string `gorm:"not null"`
   ApplicationID int `gorm:"not null"`
   Application Application
-  SensorTypeID int `gorm:"not null"`
-  SensorType SensorType
+  DeviceTypeID int `gorm:"not null"`
+  DeviceType DeviceType
   Attributes map[string]string `gorm:"serializer:json;type:jsonb"`
 }
 

src/udi/database/database.go

@@ -1,28 +1,45 @@
 package database
 
+
 import (
   "log"
-  "time"
+  //"time"
   "gorm.io/driver/postgres"
   "gorm.io/gorm"
 )
 
-func Test() {
-  dsn := ""
-  db, err := gorm.Open(postgres.Open(dsn))
-  log.Printf("Database: %s, %s", db, err)
-
-  db.AutoMigrate(&Application{})
-  db.AutoMigrate(&SensorType{})
-  db.AutoMigrate(&Sensor{})
-  db.AutoMigrate(&Measurement{})
-
-  n := time.Now()
-  m := Measurement { Time: n, Application: "bla", SensorType: "bla", Sensor: "bla", Variable: "bla", Unit: "bla", Value: 1.0 }
-  db.Create(&m)
-  m = Measurement { Time: n, Application: "bla", SensorType: "bla", Sensor: "bla", Variable: "bla", Unit: "bla", Value: 1.0 }
-  db.Create(&m)
-
-
+type DatabaseHandle struct {
+  initialized bool
+  dbh *gorm.DB 
 }
 
+func NewDatabaseHandle(dsn string) *DatabaseHandle {
+  var db DatabaseHandle
+  conn, err := gorm.Open(postgres.Open(dsn))
+  if err != nil {
+    log.Printf("Unable to open database connection: %s", err)
+    db.initialized = false
+  } else {
+    db.dbh = conn
+    db.initialized = true
+    log.Println("Database connection opened")
+  }
+  return &db
+}
+
+func (dbh *DatabaseHandle) StoreMeasurement(measurement *Measurement) {
+  if ! dbh.initialized {
+    log.Println("Database connection not initialized, can not store, measurement lost")
+    return
+  }
+
+  result := dbh.dbh.Create(measurement)
+  if result.Error != nil {
+    log.Printf("Unable to insert measurement: %s", result.Error)
+    return
+  }
+
+  log.Println("Successfully stored measurement")
+}
+
+

src/udi/database/migrate_database.go

@@ -0,0 +1,55 @@
+package database
+
+import (
+  "log"
+  //"time"
+  "gorm.io/driver/postgres"
+  "gorm.io/gorm"
+)
+
+func Migrate() {
+  dsn := ""
+  db, err := gorm.Open(postgres.Open(dsn))
+  if err != nil {
+    log.Fatalf("Unable to open database connection: %s", err)
+  }
+
+  db.AutoMigrate(&Application{})
+  log.Println("Application created")
+
+  db.AutoMigrate(&DeviceType{})
+  log.Println("DeviceType created")
+
+  db.AutoMigrate(&Device{})
+  log.Println("Device created")
+
+  db.AutoMigrate(&Measurement{})
+  log.Println("Measurement created")
+
+  log.Println("Remember to call create_hypertable on measurements, sowhat I can't do that for you.")
+
+  /*
+  m := Measurement { 
+    Time: time.Now(), 
+    Application: "app", 
+    Attributes: nil,
+    Values: []SensorType {
+      { Variable: "Temperature", Unit: "Degree Celsius", Value: 1.0 },
+      { Variable: "Temperature", Unit: "Degree Celsius", Value: 3.0 },
+    },
+  }
+  db.Create(&m)
+
+  m = Measurement { 
+    Time: time.Now(), 
+    Application: "app", 
+    Attributes: nil,
+    Values: []SensorType {
+      { Variable: "Temperature", Unit: "Degree Celsius", Value: 10.0 },
+      { Variable: "Temperature", Unit: "Degree Celsius", Value: 30.0 },
+    },
+  }
+  db.Create(&m)
+  */
+}
+