deleteNodesByTimestamp doesn't work with '$key' as 'timestampNode' parameter

[Sulomus]

Hello,
few month ago I created an discussion here in GitHub repository pointing out that the method deleteNodesByTimestamp doesn't work correctly with $key as a timestampNode parameter.

In a few days you pushed new update for the Firebase ESP32 library where this issue would be resolved. Unfortunately I didn't had time to look into this until today ...

I have updated my Firebase ESP32&ESP8266 library to the newest version: Firebase Client v3.1.5

Tried to run this code:

Serial.printf("Deleting old data... %s\n", Firebase.RTDB.deleteNodesByTimestamp(&fb_do, "/trends/GC01", "$key", 10, 20) ? "ok" : fb_do.errorReason().c_str());

And I get this error back:

Deleting old data... The device time was not set.

My firebase code setup is OK because I can write data to the database without any problem.

I am setting the time for my ESP32 as follows:

WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP, "0.cz.pool.ntp.org");
...
timeClient.begin();
timeClient.setTimeOffset(3600);

This is my database structure to which I am trying to use the deleteNodesByTimestamp:

Can you post somewhere example code with working deleteNodesByTimestamp function? Or tell me what am I doing wrong in my code so I can get this working ...

Thank you for your awesome work!
With regards,
Jakub Szlaur

[mobizt]

That is because the device system time was not set before calling that function.

The system time get from this should be a valid timestamp.

time_t now = time(nullptr);

The function description is here and the arguments are described clearly.

There is no example code for this function unless it used here to delete the log data.

[Sulomus]

Could you please point me to some docs where I can see how to correctly set up the time for my ESP32? So that the function would work correctly?

[mobizt]

You just call this to get time from NTP server (low precision).

configTime((timezone_in_seconds, daylight_offset_in_seconds, "pool.ntp.org", "time.nist.gov");

Then you need to wait until the time get from this is valid

time_t now = time(nullptr);

NTP library may be suitable for high precision internet time synching.

If you get time from RTC chip, you can set the device time with this function.

[mobizt]

I don't know how the NTP library sets the device time, if you get timestamp from it, and to make sure the system time was set properly, you can pass that timestamp to this function too.