Failed restoring a JSON from v9.3.1 onto a 9.5.0.8 device

[tasmota]

Failed restoring a JSON from v9.3.1 onto a 9.5.0.8 device

[curzon01]

This is one of the rare examples where the data structure has changed so structurally that you have to choose one of two options:

• convert the data manually within your JSON backup
• ignore the warning using -w. This will restore all except the changed structure

There is currently no functional conversion from old to new data in decode-config. Since data is simply read in on the basis of JSON identifiers, the data structures of old systems must basically be the same. A field can become larger and smaller, a variable can take on a different size, all that's handled.
This system weakens when there are structural changes. In the past, I used new JSON identifiers for the few changes of this kind (there were maybe 2 or 3), with the result that this procedure simply did not convert these fields because the new identifier did not exist in the old JSON.

I never wanted to have too much functional data dependency in decode-config, because for this I would not only have to keep track of the data structure changes in the past, but also functional dependencies. That means a lot of work when maintaining the Tasmota cmnds (-T cmnds), because I do not only track the file changes in setting.h, setting.ino and tasmota.h, but also have to pay attention to command implementations in the history. I didn't really want to add more.

[barbudor]

Thanks for the details.
Unless I missed it, this is not detailed in the manual. Worth a word and a link to this issue ?
So far the workaround I found is probably the only good one:

• Install the firmware matching the JSON backup (could be on a nodemcu if not possible on the device itself)
• Restore the backup
• Upgrade the device with the target version
• Backup JSON

[curzon01]

Install the firmware matching the JSON backup (could be on a nodemcu if not possible on the device itself)

Unnecessary, take it easy:
use your old backups and restore it on new device. Use parameter -w if warning occurs. This does what intuitively you would expect except what it can't - here it restores all from your backup from the previous release config data except sensors. This will be output during restore:

./decode-config.py -s v9_5_0_8_device  -i 9_5_0.json -w
Load data from device 'v9_5_0_8_device'
WARNING 9 (@4247): file './ 9_5_0.json' array 'sensors[3]' exceeds max number of elements [2]
WARNING 9 (@4247): file './ 9_5_0.json' array 'sensors[10]' exceeds max number of elements [4]
WARNING 9 (@4261): file './ 9_5_0.json' array 'sensors' couldn't restore, format has changed! Restore value contains <class 'str'> but an array of size [4] is expected
WARNING 9 (@4247): file './ 9_5_0.json' array 'sensors[10]' exceeds max number of elements [4]
WARNING 9 (@4261): file './ 9_5_0.json' array 'sensors' couldn't restore, format has changed! Restore value contains <class 'str'> but an array of size [4] is expected
Restore successful to device 'v9_5_0_8_device' from './ 9_5_0.json'

these are just warnings, not errors

[curzon01]

As I said, there have been two or three objects during the entire Tasmota life since v5.10 that have had such a structural change, sensors is now the fourth.
I think we can live with either adapting this single object manually in JSON or skipping it with the -w parameter.

[barbudor]

Thanks