ebus-racket: rename db.plt->db.rkt

1 files changed, 19 insertions, 4 deletions

diff --git a/ebus-racket/db.plt b/ebus-racket/db.rkt
index 050eafe..14817e5 100644
--- a/ebus-racket/db.plt
+++ b/ebus-racket/db.rkt
@@ -7,16 +7,31 @@
                          #:password "ebus"
                          #:server "10.2.2.26"))
 
+;; Query ID of sensor given by sensor-name
+;; Returns null if sensor is undefined
+(define (get-sensor-id sensor-name)
+  (with-handlers ([exn:fail?  (lambda (exn) (void))])
+    (db:query-value pgc "SELECT id FROM sensor WHERE name = $1" sensor-name)))
 
-(define (query-sensor-id sensor-name)
-  (db:query-value pgc "select id from sensor where name = $1" sensor-name))
+;; Create Sensor-ID with given name
+;; returns id
+(define (create-sensor-id sensor-name)
+  (db:query-exec "INSERT INTO sensor(name) VALUES ($1)" sensor-name)
+  (get-sensor-id sensor-name))
+
+;; Get ID of sensor given by sensor-name
+;; define sensor if needed
+(define (sensor-id sensor-name)
+  (let ([id (get-sensor-id sensor-name)])
+    (cond ((void? id) (create-sensor-id sensor-id))
+          (else id))))
 
 (define (insert sensor-name value-float value-int value-string)
-  (let ([sensor-id (query-sensor-id sensor-name)]
+  (let ([sensor-id (sensor-id sensor-name)]
         [type (cond ((not (void? value-string)) "string")
                     ((not (void? value-float)) "float")
                     ((not (void? value-int)) "int"))])
     (db:query-exec (string-append "INSERT INTO value(timestamp, sensor_id, type, value_float, value_int, value_string) "
                                   "VALUES (now(), $1, $2, $3, $4, $5)")
                    sensor-id type value-float value-int value-string)))
-  ;(db:query-exec pgc "select 
\ No newline at end of file
+