Question

I have a Erlang webapp, based on Mochiweb and Mnesia, which consumes and emits JSON. It makes sense to store records in Mnesia; however Mochiweb/Mochijson require data in proplist format. So I end up with a large amount of boilerplate code:

-record(foobar, {name, value}).

record_to_proplist(Record)->  
  [{name, Record#foobar.name},  
   {value, Record#foobar.value}].  

proplist_to_record(Props)->  
  #foobar{name=proplists:get_value("name", Props),  
          value=proplists:get_value("value", Props)}.  

Fine with a single small record, a pain with lots of large records. Can anyone suggest a way round all this boilerplate code ? I guess I need some way of inspecting a record’s fields dynamically; and since records are a compile-time construct, I’m guessing [assuming it’s possible] this means injecting code via a macro ..

Thanks!

Answer 1

It sounds like exprecs is what you’re looking for:

http://forum.trapexit.org/viewtopic.php?p=21790

Reading from the description:

The module is a parse transform
allowing you to export records. The
transform adds accessor functions for
instantiating, inspecting and
modifying records, without having to
introduce compile-time dependencies
between modules.

See if this helps.