Thank you @basdebruin
After checking, status is the columnId and I changed “Sign-Up” to “Done”, which is an existing label.
However, it did not work. Creating an item following the format still returns Internal Server Error.
Trying to update an item using this query also does not work, returning the same Internal Server Error error :
"{\"query\":\"mutation{ change_multiple_column_values(item_id:XXXX, board_id:XXXX, create_labels_if_missing: true, column_values: \"{\"status\" : {\"label\" : \"Done\"}}\"){ id} }\"}"
As for the first part, the function to call the API requires a string, which is why my first two options have quotes. I merely forgot to copy them for the third one. Is that what you meant by “escaping the initial string”? Sorry for the confusion.
And thank you @AlexSavchuk
I had checked those three links, but the StackOverflow one was promising… sadly it didn’t help.
I’m assuming I did something wrong, but I’m not sure what. I based myself on the API Quickstart Guide in Javascript, substituting stringify with its equivalent, but it returns the same Internal Server Error error.
To add some more information, I used this to make the function calling the API :
https://community.monday.com/t/basic-c-api-v2-example/3419?
When using this query :
"{\"query\": \"{boards(limit:1){id name}}\"}"
Or this mutation :
"{\"query\":\"mutation{ create_item(board_id: XXXX, group_id: XXXX, item_name: XXXX){ id} }\"}"
It works just fine
Thank you all for the help 