BeepBeep and ErlyDB integration issue

Question

Further to my adventures with Erlang and ErlyDB. I am attempting to get ErlyDB working with BeepBeep

My ErlyDB setup works correctly when run outside of the BeepBeep environment (see Debugging ErlyDB and MySQL). I have basically take the working code and attempted to get it running inside BeepBeep.

I have the following code in my controller:

handle_request("index",[]) ->
  erlydb:start(mysql,Database),
  erlydb:code_gen(["thing.erl"],mysql), 
  NewThing = thing:new_with([{name, "name"},{value, "value"}]),
  thing:save(NewThing),
  {render,"home/index.html",[{data,"Hello World!"}]};

When I call the URL, the response outputs "Server Error". There is no other error or exception information reported.

I have tried wrapping the call in try/catch to see if there is an underlying error - there is definitely an exception at the call to thing:new_with(), but no further information is available.

The stacktrace reports:

{thing,new,[["name","value"]]}
{home_controller,create,1}
{home_controller,handle_request,3}
{beepbeep,process_request,4}
{test_web,loop,1}
{mochiweb_http,headers,4}
{proc_lib,init_p_do_apply,3}

Answer 1

Use pattern matching to assert that things work up to the call to thing:new/1:

ok = erlydb:start(mysql,Database),
ok = erlydb:code_gen(["thing.erl"],mysql),

You include only the stack trace, look at the exception message as well. I suspect that the error is that you get an 'undef' exception. But check that it is so. The first line in the stack trace indicates that it is a problem with calling thing:new/1 with ["name", "value"] as argument.

It is slightly odd that you show one clause of handle_request that is not calling home_controller:create/1 as per {home_controller,create,1} in the stack-trace. What do the other clauses in your handle_request/2 function look like?