· Sep 27, 2019 2m read

Error Handling Techniques : Tips & Tricks

At least three different ways to process errors (status codes, exceptions, SQLCODE etc is given in ObjectScript. Most systems have status, but for a range of reasons exceptions are more convenient to manage. You spend some time translating between the various techniques dealing with legacy code. For reference, I use several of these excerpts. It is hoped that they will also support others.

///Status from SQLCODE:
set st = $$$ERROR($$$SQLError, SQLCODE, $g(%msg))  //embedded SQL
set st = $$$ERROR($$$SQLError, rs.%SQLCODE, $g(rs.%Message)) //dynamic SQL
///Exception from SQLCODE:
throw ##class(%Exception.SQL).CreateFromSQLCODE(SQLCODE,%msg) //embedded SQL
throw ##class(%Exception.SQL).CreateFromSQLCODE(rs.%SQLCODE,rs.%Message) //dynamic SQL
throw:(SQLCODE'=0)&&(SQLCODE'=100) ##class(%Exception.SQL).CreateFromSQLCODE(SQLCODE,%msg) //don't throw if query succeeds or finds no data 
///Exception from status:
///Status from exception:
set st = err.AsStatus()
///Creating a custom error status:
set st = $$$ERROR($$$GeneralError,"Custom error message")
///Throwing a custom exception:
$$$ThrowStatus($$$ERROR($$$GeneralError,"Custom error message"))
///Handling a SOAP error with a status:
try {
  //SOAP request code
} Catch err {
  If err.Name["ZSOAP" {
    Set st = %objlasterror
  } Else {
    Set st = err.AsStatus()
return st
///Defining a custom exception class
Class App.Exceptions.SomeException Extends %Exception.AbstractException
Method OnAsStatus() As %Status
  return $$$ERROR($$$GeneralError,"Custom error message")
///Throwing and catching a custom exception
try {
  throw ##class(App.Exceptions.SomeException).%New()
} catch err {
  if err.%ClassName(1) = ##class(App.Exceptions.SomeException).%ClassName(1) {
    //some handling unique to this type of exception
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