Is there a list of JSON parse error codes? - ruby-on-rails

Question

I'm trying to provide a good experience to users that are using JSON and the parser is on the backend (Ruby).
Most of the time, when you get a badly formatted JSON payload the error is of the format XXX unexpected token at '<entire payload here>'. That's not very user-friendly nor practical.
My question is: Is there a list of the XXX error codes that could help create better error messages that could be understood by beginners and not-really-tech-people?
Thanks!

Answer 1

XXX in this kind of errors is not a special code of the error. It is just a line number from the file where this error was raised. For example, for Ruby 2.5.1 you'll get JSON::ParserError (765: unexpected token at https://github.com/ruby/ruby/blob/v2_5_1/ext/json/parser/parser.rl#L765

Answer 2

You can find a list in the documentation for the module.
Think this covers it:
JSON::JSONError
JSON::GeneratorError
JSON::GenericObject
# The base exception for JSON errors.
JSON::MissingUnicodeSupport
# This exception is raised if the required unicode support is missing on the system. Usually this means that the iconv library is not installed.
JSON::NestingError
# This exception is raised if the nesting of parsed data structures is too deep.
JSON::ParserError
# This exception is raised if a parser error occurs.
JSON::UnparserError
# This exception is raised if a generator or unparser error occurs.
JSON::JSONError is the parent class, so you can rescue from that and provide per-error-class messages as needed.
I feel it's worth noting that in my experience the vast majority of errors relating to JSON are of the class JSON::ParserError. Another common issue worth considering is getting ArgumentError if nil is passed as an argument.
As an example of how this could be used, you could work with something like the following:
begin
JSON.parse(your_json)
rescue JSON::JSONError, ArgumentError => e
{ error: I18n.t(e.to_s) } # <- or whatever you want to do per error
end
Hope that helps - let me know how you get on :)