[elephant-devel] Help with an error on app startup/initialization

[Yarek Kowalik]

I've converted my weblocks app to use elephant.  One of the first things I
do is to initialize some variables.  One of the variables is a "demo" item,
that I use as a placeholder until the user choses something more specific.
I'm having trouble initializing the dummy.  Here is my code:

(defun init-dummy-item ()
  (let* ((ref-type 0)
         (ref-id "dummy-item"))
    (setf *dummy-item*
          (unless-use (awhen (elephant:get-instances-by-value 'product-item
'reference-id ref-id)
                        (find-if (lambda (item)
                                   (eql (product-item-reference-type item)
ref-type))
                                 it))
                      (make-instance
                       'product-item
                       :reference-type    ref-type
                       :reference-id    ref-id
                       :title        "No Item selected"
                       :url        "/pub/static/dummy.html"
                       :image-url    "/pub/images/dummy.png")))))

(The UNLESS-USE macro simply does unless, and if results are nil uses the
second sexp.)

The problem is that I get an error (see trace below) when calling
GET-INSTANCES-BY-VALUE.  What am I doing wrong?

The nearest that I can gather is that GET-VALUE is called with the secondd
argument as  NIL, but it's supposed to be something reasonable, i.e a
controller-index-table held by the controler.  For whatever raeson that's
NIL.   What's the deal here?  Am I not alowed to call the get-instances-by-*
methods until I create at least one item for each class I'm querying about?

Yarek

THE ERROR:

There is no applicable method for the generic function
  #<STANDARD-GENERIC-FUNCTION ELEPHANT:GET-VALUE (3)>
when called with arguments
  ((FASHION-ORIGAMI::PRODUCT-ITEM
    . FASHION-ORIGAMI::REFERENCE-ID)
   NIL).
   [Condition of type SIMPLE-ERROR]

Restarts:
 0: [TERMINATE-THREAD] Terminate this thread (#<THREAD
"hunchentoot-worker-4" RUNNING {10029A0321}>)

Backtrace:
  0: ((LAMBDA (SWANK-BACKEND::DEBUGGER-LOOP-FN)) #<FUNCTION (LAMBDA #)
{1003F6A4C9}>)
  1: (SWANK::DEBUG-IN-EMACS #<SIMPLE-ERROR {1002E3A1A1}>)
  2: ((LAMBDA (SWANK-BACKEND::HOOK SWANK-BACKEND::FUN)) #<FUNCTION
SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA #) {1002E3A9D9}>)
  3: (SWANK::CALL-WITH-REDIRECTED-IO #<SWANK::CONNECTION {10037B86D1}>
#<CLOSURE (LAMBDA #) {1002E3A9F9}>)
  4: (SWANK::CALL-WITH-CONNECTION #<SWANK::CONNECTION {10037B86D1}>
#<CLOSURE (LAMBDA #) {1002E3A9D9}>)
  5: (SWANK:INVOKE-SLIME-DEBUGGER #<SIMPLE-ERROR {1002E3A1A1}>)
  6: ((LAMBDA (SWANK-BACKEND::HOOK SWANK-BACKEND::FUN)) #<FUNCTION
SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA #) {1002E3A999}>)
  7: (INVOKE-DEBUGGER #<SIMPLE-ERROR {1002E3A1A1}>)
  8: (INVOKE-DEBUGGER #<SIMPLE-ERROR {1002E3A1A1}>)[:EXTERNAL]
  9: ((SB-PCL::FAST-METHOD HUNCHENTOOT:MAYBE-INVOKE-DEBUGGER (T))
#<unavailable argument> #<unavailable argument> #<SIMPLE-ERROR
{1002E3A1A1}>)
 10: (SIGNAL #<SIMPLE-ERROR {1002E3A1A1}>)[:EXTERNAL]
 11: (ERROR #<SIMPLE-ERROR {1002E3A1A1}>)[:EXTERNAL]
 12: ((FLET #:LAMBDA43) #<SIMPLE-ERROR {1002E3A1A1}>)
 13: ((FLET #:LAMBDA43) #<SIMPLE-ERROR {1002E3A1A1}>)[:EXTERNAL]
 14: (SIGNAL #<SIMPLE-ERROR {1002E3A1A1}>)[:EXTERNAL]
 15: (ERROR "~@<There is no applicable method for the generic function
~2I~_~S~\n          ~I~_when called with arguments ~2I~_~S.~:>")[:EXTERNAL]
      Locals:
        SB-DEBUG::ARG-0 = 3
        SB-DEBUG::ARG-1 = "~@<There is no applicable method for the generic
function ~2I~_~S~\n      ..
 16: ((SB-PCL::FAST-METHOD NO-APPLICABLE-METHOD (T)) #<unavailable argument>
#<unavailable argument> #<STANDARD-GENERIC-FUNCTION ELEPHANT:GET-VALUE
(3)>)[:EXTERNAL]
      Locals:
        SB-DEBUG::ARG-0 = 5
        SB-DEBUG::ARG-1 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-2 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-3 = #<STANDARD-GENERIC-FUNCTION ELEPHANT:GET-VALUE
(3)>
 17: (ELEPHANT::ENSURE-SLOT-DEF-INDEX #<unavailable argument> #<unavailable
argument>)
      Locals:
        SB-DEBUG::ARG-0 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-1 = :<NOT-AVAILABLE>
 18: ((SB-PCL::FAST-METHOD ELEPHANT:FIND-INVERTED-INDEX
(ELEPHANT:PERSISTENT-METACLASS T)) #<unavailable argument> #<unavailable
argument> #<unavailable argument> #<unavailable argument>)[:EXTERNAL]
      Locals:
        SB-DEBUG::ARG-0 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-1 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-2 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-3 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-4 = :<NOT-AVAILABLE>
 19: (ELEPHANT:MAP-INVERTED-INDEX #<unavailable argument> #<unavailable
argument> #<unavailable argument>)[:EXTERNAL]
      Locals:
        SB-DEBUG::ARG-0 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-1 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-2 = :<NOT-AVAILABLE>
        SB-DEBUG::ARG-3 = :<NOT-AVAILABLE>
 20: (FASHION-ORIGAMI::INIT-DUMMY-ITEM)
      Locals:
        #:G137 = :<NOT-AVAILABLE>
        ANAPHORA:IT = :<NOT-AVAILABLE>
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