[erlang-questions] JSON Parser

[Michael Truog]

On 07/15/2015 11:24 AM, Bob Ippolito wrote:
> Records are a compile time construct, so in order to parse as records you'd need to define the records in advance and provide a schema and record definition to the parser for the document. This could be done in a layer above the JSON parser.
>
One approach which is possible for the record approach, is to use the parse transform https://github.com/okeuday/record_info_runtime/ with a function the parse transform adds: record_info_fieldtypes/1. So, then the Erlang type spec information is accessible along with the fields based on the record name, to determine any details for encoding into JSON or decoding from JSON.  The nice part of that approach is then that the type spec information allows validation to catch problems, if there are any, like with nested record structures.  Not sure about the best way to encapsulate that approach, but I know it has worked in the past.

>
> Maps are the data structure you're looking for. Most of the JSON implementations provide backwards compatibility to versions of Erlang before maps, so other data structures (such as dicts or proplists) are more common.
>
> On Wednesday, July 15, 2015, Kannan <vasdeveloper@REDACTED <mailto:vasdeveloper@REDACTED>> wrote:
>
>     Is any of them supporting Erlang 'record' as their base for encoding/decoding. I see many of them are doing it with just list of tuples of binaries.Erlang records best match the structure of JSON format.
>
>     JSON
>     ----------
>     {"name": "Theepan",
>       "work": "Coding",
>       "salary": "0"
>     }
>
>     Matching Erlang record
>     -----------------------------------
>     -record( json_record,
>     {
>       'name' = "Theepan",
>       'work' = "Coding",
>       'salary' = "0"
>     }
>     }
>
>     Thanks,
>     Theepan
>
>     On Wed, Jul 15, 2015 at 2:33 PM, Jesper Louis Andersen <jesper.louis.andersen@REDACTED <javascript:_e(%7B%7D,'cvml','jesper.louis.andersen@REDACTED');>> wrote:
>
>
>         On Tue, Jul 14, 2015 at 10:06 PM, Kannan <vasdeveloper@REDACTED <javascript:_e(%7B%7D,'cvml','vasdeveloper@REDACTED');>> wrote:
>
>             I come across many JSON libraries. Once from MochiWeb, Other one from Yaws. Third one from CouchDB. And some others through Googling.
>
>
>         There are two very popular JSON parsers in Erlang: jsx and jiffy.
>
>         jsx is written in plain Erlang. It is fast, correct and since it is written in Erlang, it will also automatically yield for other processes in the system.
>
>         jiffy is written as a C NIF. It is about 10 times faster than jsx, but the caveat is everything that has to do with C NIFs: blocking a scheduler, C code having errors, security considerations, etc.
>
>         I tend to run with `jsx` in my projects, and then I switch away from JSON when it gets to slow. JSON is a bad format that should never have existed in the first place. We are stuck with it because it's historic alternative, XML, was far worse in every aspect.
>
>
>         -- 
>         J.
>
>
>
>
> _______________________________________________
> erlang-questions mailing list
> erlang-questions@REDACTED
> http://erlang.org/mailman/listinfo/erlang-questions

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://erlang.org/pipermail/erlang-questions/attachments/20150715/0118a8e9/attachment.htm>