check object json

[david31]

Hello

I would if it's possible to test if an object exist on response json

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{
"tickets": [],
"links": [],
"disruptions": [],
"notes": [],
"feed_publishers": [],
"context": {
"timezone": "Europe/Paris",
"current_datetime": "20180402T213237"
},
"error": {
"message": "no solution found for this journey",
"id": "no_solution"
},
"exceptions": []
}

When no data, the field error exist
when data exist, the field error don't exist

i have test

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jsonLocation.error.id == "no_solution"

but i have

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[string "commandArray = {} ..."]:43: attempt to index field 'error' (a nil value)

when the field don't exist

[david31]

i have found this and it work fine

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string.match(jsondevices, "error", 1)