cheatsheet-errors

MDL Common Errors Cheatsheet

Quick fixes for common MDL syntax errors.

Variable Errors

"Variable 'X' is not declared"

Problem: Using SET on a variable that wasn't declared.

-- WRONG
if $value > 10 then
  set $IsValid = false;  -- ERROR: $IsValid not declared
end if;

Fix: Add DECLARE before SET.

-- CORRECT
declare $IsValid boolean = true;
if $value > 10 then
  set $IsValid = false;
end if;

"Selected type is not allowed" (CE0053)

Problem: Declaring an object (entity) or list variable. A declare maps to a Create Variable activity, which only accepts primitives (String/Integer/Long/Decimal/Boolean/DateTime/Enumeration). Declaring an object or list is rejected (CE0053/CE0038, plus CE7247 on any later set) — bare or initialized. The as keyword is also a parse error in mxcli. mxcli check flags an object declare as MDL043 and a list declare as MDL040.

-- WRONG: declaring an object — there is no "empty object variable" (MDL043)
declare $Product Module.Product = empty;
declare $Product as Module.Product;         -- AS is also a parse error
-- WRONG: declaring a list (MDL040)
declare $Products list of Module.Product = empty;

Fix: Objects and lists can't be declared — get them from a source that produces one.

-- object: a microflow parameter, a retrieve, a create, or a loop iterator
retrieve $Product from Module.Product where Code = $Code limit 1;  -- retrieve
$Product = create Module.Product (Name = $Name);                   -- create
-- or: create microflow M.Save ($Product: Module.Product) ... / loop $Product in $Products ...

-- list: a parameter, a retrieve, or a create list
$Products = create list of Module.Product;   -- empty list to accumulate into
retrieve $Products from Module.Product where ...;  -- or populate from the database

Expression Errors

"Error in expression" (CE0117)

Problem 1: Using unqualified association name in XPath.

-- WRONG: Missing module qualification
set $Name = $Order/Customer/Name;