Incorrect storage of some data

[jteg68]

Hi,

I think this is a MxChartDB bug as I couldn't see any corresponding log messages in z-way.

When configuring trends yesterday, with the MxChartDB version from the app store, there were some measurments stored incorrectly in the database. Instead of for example the temperature 25.4, a string "25.4" was stored. The trend display issued error messages like this one:
sensor=2, point=35, Time=2025-07-13 11:46:30: you cannot mix numeric and text labels! 25.4 >< 24.98

At a quick glance this seemed to happen when a new signal was added, but not for everyone of them. An example from the database below:

sqlite> select * from MxChartDB18 where val like '%"25%';
1752399721257|[1752399721257, 25.16, "25.4"]
1752399792046|[1752399792046, 25.16, "25.4"]
1752399852310|[1752399852310, 25.16, "25.4"]
1752399911587|[1752399911587, 25.16, "25.4"]
1752399971851|[1752399971851, 25.16, "25.4"]
1752399978651|[1752399978651, 24.6200016, "25.4"]

In the data view the numbers are shown correctly as numbers, not strings, but with the same font colour as the timestamp (string). Maybe that is the caused by the browser.

The error messages appear with the latest version from github as well as with the one from app store.

Thanks,
Jörgen

[piet66-peb]

Hi Jörgen,
I will explain how this comes about. I admit it's a bit complicated.
It has to do with the fact that MxChartDB is able to process and display both types, numeric and alphanumeric values. And it tries to automatically determine what type the values are.
In this case, it appears that some of the sensor readings are stored as strings.
Please compare the two types of 25.4 >< 24.98.

As a workaround, I recommend recoding the value into the numeric type in Arithmetic operation for the display, e.g. with 'x-0'. With this command, Javascript will convert x to a number, if it's a string.

[jteg68]

Thanks, this is not a real problem as it seems only a few datapoints in the beginning was stores as strings.

[piet66-peb]

Thanks for the response.
To make it clear: I think it's a problem of Z-Way. Probably it has stored these numbers in string format instead of numeric format in the virtual device.
MxChartDB takes the values from the devices and stores them into the database without change. It's only a simple function, and I see no reason why this sometimes shouldn't work correctly. I have never seen such an effect.

If you nevertheless notice a case where something like this happens, I have to investigate this. In this case, I would be grateful for any information. Please include the contents of the virtual device in addition to the extract from the database.
Please add also both version numbers, of MxChartDB and of MxChartDB_API.py.