Parsing JSON in Erlang

Question

I have a piece of JSON string, which I want to parse in Erlang. It looks like:

({ id1 : ["str1", "str2", "str3"], id2 : ["str4", "str5"]})

I looked at mochijson2, and a couple of other JSON parsers, but I really could not figure out how to do it. Any help greatly appreciated!

Solution 1

I once used the erlang-json-eep-parser, and tried it on your data.

7> json_eep:json_to_term("({ id1 : [\"str1\", \"str2\", \"str3\"], id2 : [\"str4\", \"str5\"]})").
** exception error: no match of right hand side value 
                    {error,{1,json_lex2,{illegal,"("}},1}
     in function  json_eep:json_to_term/1

Right, it doesn't like the parentheses.

8> json_eep:json_to_term("{ id1 : [\"str1\", \"str2\", \"str3\"], id2 : [\"str4\", \"str5\"]}").
** exception error: no match of right hand side value 
                    {error,{1,json_lex2,{illegal,"i"}},1}
     in function  json_eep:json_to_term/1

And it doesn't like the unquoted keys:

18> json_eep:json_to_term("{ \"id1\" : [\"str1\", \"str2\", \"str3\"], \"id2\" : [\"str4\", \"str5\"]}").
{[{<<"id1">>,[<<"str1">>,<<"str2">>,<<"str3">>]},
  {<<"id2">>,[<<"str4">>,<<"str5">>]}]}

That looks better.

So it seems that your data is almost JSON, at least as far as this parser is concerned.

Solution 2

you can work on your JSON at the JSONLint validator: http://www.jsonlint.com/

Solution 3

Your input is not quite JSON -- the keys need to be quoted, like this:

{ "id1" : ["str1", "str2", "str3"], "id2" : ["str4", "str5"]}

A good Erlang library for manipulating JSON is jsx

Comments

[cdmckay]

That's not true JSON. The keys need to be quoted and there should be no brackets around it.

[Blauohr]

Sorry I see the erlang-json-parser is "Service Temporarily Unavailable"

[thomas55]

Yes, I saw the RFC4627 implementation, but when I pass the above string as input to the decode() function, I am getting a "badarg" error...