Implement Database.update() to change only modified columns

lib/nntp/tiny/db.py

@@ -110,6 +110,21 @@ class Database():
 
         setattr(obj, table.key, cr.lastrowid)
 
+    def update(self, obj):
+        if not obj.__dirty__:
+            return
+
+        dirty = [k for k in obj.__dirty_columns__ if obj.__dirty_columns__[k] > 0]
+        table = type(obj)
+        sql  = f"update {table.name} set "
+        sql += ", ".join([f"{k} = ?" for k in dirty])
+        sql += f" where {table.key} = ?"
+
+        values = [getattr(obj, k) for k in dirty]
+        values.append(getattr(obj, table.key))
+
+        self.db.execute(sql, values)
+
     def query_sql(self, table, sql, values=list()):
         cr = DatabaseTableCursor(table, self.db.cursor())
         cr.execute(sql, values)