Merge pull request #1167 from ingoratsdorf/db-work

DB result iteration fix on empty result

server/db/db_helper.py

@@ -6,7 +6,8 @@ INSTALL_PATH="/app"
 sys.path.extend([f"{INSTALL_PATH}/server"])
 
 from helper import if_byte_then_to_str
-from logger import mylog  
+from logger import mylog
+
 
 #-------------------------------------------------------------------------------
 #  Return the SQL WHERE clause for filtering devices based on their status.
@@ -41,7 +42,6 @@ def get_device_condition_by_status(device_status):
     return conditions.get(device_status, 'WHERE 1=0')
 
 
-
 #-------------------------------------------------------------------------------
 #  Creates a JSON-like dictionary from a database row
 def row_to_json(names, row):
@@ -71,6 +71,7 @@ def row_to_json(names, row):
 
     return rowEntry
 
+
 #-------------------------------------------------------------------------------
 def sanitize_SQL_input(val):
     """
@@ -116,7 +117,6 @@ def get_date_from_period(period):
     return period_sql
 
 
-
 #-------------------------------------------------------------------------------
 def print_table_schema(db, table):
     """
@@ -193,15 +193,21 @@ def get_table_json(sql, sql_query):
     """
     try:
         sql.execute(sql_query)
-        column_names = [col[0] for col in sql.description]
         rows = sql.fetchall()
+        if (rows):
+            # We only return data if we actually got some out of SQLite
+            column_names = [col[0] for col in sql.description]
+            data = [row_to_json(column_names, row) for row in rows]
+            return json_obj({"data": data}, column_names)
     except sqlite3.Error as e:
+        # SQLite error, e.g. malformed query
         mylog('verbose', ['[Database] - SQL ERROR: ', e])
-        return json_obj({}, [])  # return empty object
-
-    result = {"data": [row_to_json(column_names, row) for row in rows]}
-    return json_obj(result, column_names)
-
+    except Exception as e:
+        # Catch-all for other exceptions, e.g. iteration error
+        mylog('verbose', ['[Database] - Unexpected ERROR: ', e])
+        
+    # In case of any error or no data, return empty object
+    return json_obj({"data": []}, [])
 
 #-------------------------------------------------------------------------------
 class json_obj: