Re: [Erlyaws-list] JSON formatted data

[<wd...@fr...>]

Hello steve,

>> Hi all,
>>
>>  I'm trying to return JSON data from Yaws.
>
>As always, it would be good to indicate which version of Yaws you're using.
>
>>  But I got an error when I parse the result with Javascript on the client browser side.
>>
>>  For example :
>>
>>  The string to return is : <<"t\"est">>
>
>Note that that's a binary, not a string.

Yes sorry for this confusion.


>
>>  The json encoding process : json:encode({struct,[{variable,<<"t\"est">>}]})
>
>Running the latest svn version of yaws under R12B-4, I get:
>
>Eshell V5.6.4  (abort with ^G)
>1> json:encode({struct,[{variable,<<"t\"est">>}]}).
>** exception exit: {json_encode,{bad_term,<<"t\"est">>}}
>     in function  json:encode/1
>     in call from lists:foldl/3
>     in call from json:encode_object/1
>
>If I make it a string, then it works:
>
>2> json:encode({struct,[{variable,"t\"est"}]}).
>[123,["\"variable\"",58,"\"t\\\"est\""],125]
>3> lists:flatten(json:encode({struct,[{variable,"t\"est"}]})).
>"{\"variable\":\"t\\\"est\"}"
>
>Are you using a json module that's different from what yaws supplies?
>

Yes, i added a case for the encode function :

"encode(B) when is_binary(B) -> encode(binary_to_list(B));"



>>  After json encoding we have :
>>
>>  <<"{\"variable\":\"t\\\"est\"}">>
>
>That too is a binary. We actually have:
>
>"{\"variable\":\"t\\\"est\"}"
>
>>  Note the "triple" \ to respect the json format
>
>Indeed. Note also that it's needed only because the whole thing is
>within double quotes. Look what happens when you print it:
>
>4> io:format("~s~n",
>[lists:flatten(json:encode({struct,[{variable,"t\"est"}]}))]).
>{"variable":"t\"est"}
>
>>  The yaws page :
>>
>>  <erl>
>>         out(Arg) ->
>>                 {html, json:encode({struct,[{variable,<<"t\"est">>}]})}.
>>  </erl>
>
>Or better yet:
>
><erl>
>       out(Arg) ->
>               {content, "application/json",
>json:encode({struct,[{variable,"t\"est"}]})}.
></erl>
>
>>  Finally I received on the client side this string :
>>
>>  {"variable":"t\"est"}
>
>which is exactly right.
>
>>  This format do not respect the JSON standard.
>
>Sure it does.

You are right. 
>
>>  How could I handle this case ?
>
>There's nothing to handle, as it's already correct:
>
>First, from my bash shell I create the same .yaws file as above:
>
>$ cat > tmp/foo.yaws
><erl>
>out(Arg) ->
>    {content, "application/json", json:encode({struct,[{variable,"t\"est"}]})}.
></erl>
>

>I then run the Rhino JavaScript interpreter:
>
>$ rhino
>Rhino 1.7 release 1 2008 03 06
>js> eval("var json = " + readUrl("http://localhost/tmp/foo.yaws"));
>js> json
>[object Object]
>js> json.variable
>t"est
>
>which is exactly what I'd expect to get.
>

Yes it works, my parser on the client side was badly used.



>>  Thank you for your help.
>
>No problem.
>
>--steve
>

Thank you.