support query device data from old db (#64)

cmd/server/config/config.go

@@ -16,6 +16,7 @@ type Config struct {
 	ServiceEndpoint          string     `env:"HTTP_SERVICE_ENDPOINT"`
 	PrvKey                   string     `env:"PRIVATE_KEY,optional"`
 	DatabaseDSN              string     `env:"DATABASE_DSN"`
+	OldDatabaseDSN           string     `env:"OLD_DATABASE_DSN"`
 	ChainEndpoint            string     `env:"CHAIN_ENDPOINT,optional"`
 	BeginningBlockNumber     uint64     `env:"BEGINNING_BLOCK_NUMBER,optional"`
 	IoIDProjectID            uint64     `env:"IOID_PROJECT_ID,optional"`

cmd/server/main.go

@@ -31,7 +31,7 @@ func main() {
 		log.Fatal(errors.Wrap(err, "failed to parse private key"))
 	}
 
-	db, err := db.New(cfg.DatabaseDSN)
+	db, err := db.New(cfg.DatabaseDSN, cfg.OldDatabaseDSN)
 	if err != nil {
 		log.Fatal(errors.Wrap(err, "failed to new db"))
 	}

db/device_record.go

@@ -43,15 +43,29 @@ func (d *DB) QueryDeviceRecord(latitude, longitude string) (*DeviceRecord, error
 	if err := d.db.Raw(fmt.Sprintf(sql, longitude, latitude)).Scan(&ids).Error; err != nil {
 		return nil, errors.Wrap(err, "failed to query device record geo data")
 	}
-	if len(ids) == 0 {
+	if len(ids) != 0 {
+		t := &DeviceRecord{}
+		if err := d.db.Where("id IN ?", ids).Order("timestamp DESC").First(&t).Error; err != nil {
+			if err == gorm.ErrRecordNotFound {
+				return nil, nil
+			}
+			return nil, errors.Wrap(err, "failed to query device record")
+		}
+		return t, nil
+	}
+	oldIDs := []string{}
+	if err := d.oldDB.Raw(fmt.Sprintf(sql, longitude, latitude)).Scan(&ids).Error; err != nil {
+		return nil, errors.Wrap(err, "failed to query device record geo data from old db")
+	}
+	if len(oldIDs) == 0 {
 		return nil, nil
 	}
 	t := &DeviceRecord{}
-	if err := d.db.Where("id IN ?", ids).Order("timestamp DESC").First(&t).Error; err != nil {
+	if err := d.oldDB.Where("id IN ?", oldIDs).Order("timestamp DESC").First(&t).Error; err != nil {
 		if err == gorm.ErrRecordNotFound {
 			return nil, nil
 		}
-		return nil, errors.Wrap(err, "failed to query device record")
+		return nil, errors.Wrap(err, "failed to query device record from old db")
 	}
 	return t, nil
 }

db/postgres.go

@@ -8,10 +8,11 @@ import (
 )
 
 type DB struct {
-	db *gorm.DB
+	db    *gorm.DB
+	oldDB *gorm.DB
 }
 
-func New(dsn string) (*DB, error) {
+func New(dsn, oldDSN string) (*DB, error) {
 	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{
 		Logger: logger.Default.LogMode(logger.Silent),
 	})
@@ -32,5 +33,14 @@ func New(dsn string) (*DB, error) {
 	); err != nil {
 		return nil, errors.Wrap(err, "failed to migrate model")
 	}
-	return &DB{db}, nil
+	oldDB, err := gorm.Open(postgres.Open(oldDSN), &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Silent),
+	})
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to connect old postgres")
+	}
+	return &DB{
+		db:    db,
+		oldDB: oldDB,
+	}, nil
 }