[db] remove non-working trigger to manage it into python code

db/pyheatpump.sql

@@ -21,7 +21,7 @@ CREATE TABLE IF NOT EXISTS variable (
 CREATE TABLE IF NOT EXISTS var_value (
   type CHAR(1) NOT NULL,
   address INT NOT NULL,
-  time INT DEFAULT CURRENT_TIMESTAMP,
+  time INT DEFAULT (strftime('%s', datetime('now'))),
   value INT NOT NULL,
 
   FOREIGN KEY (type) REFERENCES variable(type)
@@ -38,24 +38,6 @@ INSERT INTO var_type (slabel, label, type, start_address, end_address) VALUES (
 INSERT INTO var_type (slabel, label, type, start_address, end_address) VALUES (
   'D', 'Digital', 'bool', 1, 2048);
 
-CREATE TRIGGER variable_insert BEFORE INSERT ON var_value
-FOR EACH ROW
-WHEN
-  NOT EXISTS (
-    SELECT MAX(time) FROM var_value
-    WHERE
-      NEW.type = type
-      AND
-      NEW.address = address
-      AND
-      NEW.value = value
-  )
-BEGIN
-  INSERT INTO var_value
-  (type, address, value)
-  VALUES (NEW.type, NEW.address, NEW.value);
-END;
-
 CREATE TRIGGER variable_last_update AFTER INSERT ON var_value
 FOR EACH ROW
 BEGIN

pyheatpump/models/variable_value.py

@@ -27,14 +27,24 @@ class VariableValue(RowClass):
 
     def insert(self):
 
+        try:
+            old_value = VariableValue.get(
+                self.type,
+                self.address)
+            if old_value.value == self.value:
+                # last variable value is equal to current value
+                # so do not insert
+                return False
+        except StopIteration:
+            # variable value was never inserted
+            pass
+
         try:
             sql(
-            """
-            INSERT INTO var_value
+            """INSERT INTO var_value
             (type, address, value)
             VALUES
-            ('{}', {}, {})
-            """.format(
+            ('{}', {}, {})""".format(
                 self.type, self.address, self.value
             ))
             return True
@@ -50,15 +60,13 @@ class VariableValue(RowClass):
     def get(type, address, time=datetime.now()):
         try:
             row = next(sql(
-            """
-                SELECT * FROM var_value
-                WHERE
-                    type = '{}'
-                    AND address = {}
-                    AND time <= {}
-                ORDER BY time DESC
-                LIMIT 1
-            """.format(
+            """SELECT * FROM var_value
+            WHERE
+                type = '{}'
+                AND address = {}
+                AND time <= {}
+            ORDER BY time DESC
+            LIMIT 1""".format(
                 type, address, int(time.strftime('%s'))+1
             )))
             return VariableValue(**dict(row))