duplicate key

[ilyasamraoui]

Hi,
DesrializationError validate json char array that has duplicate key

[bblanchon]

Hi @ilyasamraoui,

Indeed, the goal of ArduinoJson is to offer a lightweight parser for embedded platforms and not a JSON validator.
I don't think it's worth increasing the size of the code for such an edge case.

Do you have a use case where detecting duplicate keys is crucial?

Best Regards,
Benoit

[bblanchon]

I just made the test and the code grew by only 26 bytes; so that may be worth it.
But do we really need this?

[bblanchon]

Looking at this question on stackoverflow, I realized that duplicate keys are not illegal and are accepted by most implementations.

All major implementations keep the last value:

• Chrome 77: JSON.parse('{"a":1,"a":2}') -> {a: 2}
• IE 11: JSON.parse('{"a":1,"a":2}') -> {a: 2}
• Edge 44: JSON.parse('{"a":1,"a":2}') -> {a: 2}
• Firefox 68: JSON.parse('{"a":1,"a":2}') -> {a: 2}
• Python 3.6.8: json.loads('{"a":1,"a":2}') -> {'a': 2}
• Ruby: JSON.parse('{"a":1,"a":2}') -> {"a"=>2}

So deserializeJson() should return Ok, but the JsonDocument should contain the last value.

[ilyasamraoui]

ok i see, i used jsonlint.com to validate json object with duplicate key and it didn't validate it

[bblanchon]

Fix published in ArduinoJson 6.13.0