Error Handling

If errors occur in your custom action handler, perform the following to route error information back to the UI for display and possible troubleshooting purposes.

The easiest way to demonstrate this is to take a look at the sample below; which generates an error and returns the action-result back to Ballot with associated effects.

Sample:

/-  *plugin, ballot, res=resource, inv=invite-store
|%
++  on
  |=  [=bowl:gall store=state-1:ballot context=[booth-key=@t proposal-key=@t]]
  |%
    ++  action
      |=  [action-data=json payload=json]
      ^-  action-result
      =|  result=action-result
      :: force an error by:
      ::   1) setting the success property to %.n
      ::   2) giving a gift back to the booth owner ship (the one on which
      ::      this custom action is running) with an error reaction/effect
      =.  success.result  %.n
      =.  effects.result  (generate-error "testing custom action error. please ignore.")
      ::  return the action-result back to Ballot so the gift can be delivered
      result
    ++  generate-error
      |=  [err=tape]
      ^-  (list card:agent:gall)
      =/  context=json
      %-  pairs:enjs:format
      :~
        ['booth' s+booth-key.context]
        ['proposal' s+proposal-key.context]
      ==
      =/  error-data=json
      %-  pairs:enjs:format
      :~
        ['error' s+(crip err)]
      ==
      =/  error-effect=json
      %-  pairs:enjs:format
      :~
        ['resource' s+'proposal']
        ['effect' s+'error']
        ['data' error-data]
      ==
      ::  if we assume the custom action was 'invite-member', the error
      ::   should appears as follows:
      =/  effects=json
      %-  pairs:enjs:format
      :~
        ['action' s+'invite-member-reaction']
        ['context' context]
        ['effects' [%a [error-effect]~]]
      ==
      :~  [%give %fact [/booths]~ %json !>(effects)]
      ==
  --
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