cheatsheet-errors

name	cheatsheet-errors
description	MDL Common Errors Cheatsheet — quick fixes for variable, expression, control flow, syntax, and reference errors with Studio Pro error code reference
compatibility	opencode

MDL error reference — quick lookup for common MDL syntax and runtime errors with corrected code examples.

> Quick fixes for common MDL syntax errors. Covers variable declaration errors, expression errors, control flow errors, syntax errors, reference errors, and a Studio Pro error code table.

Load when: - An MDL script produces a syntax or compile error - Debugging CE0053, CE0104, CE0105, CE0117, or CW0094 errors - Looking up the correct syntax for a specific pattern

<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: Wrong syntax for entity type declaration.

-- WRONG: Missing AS keyword
declare $Product Module.Product = empty;

Fix: Use AS keyword for entity types.

-- CORRECT
declare $Product as Module.Product;

</variable_errors>

<expression_errors>

"Error in expression" (CE0117)

Problem: Using unqualified association name in XPath.

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

Fix: Use fully qualified association name.

-- CORRECT: Module.AssociationName
set $Name = $Order/Shop.Order_Customer/Name;

"Type mismatch" in enum comparison

Problem: Comparing enumeration with string literal.

-- WRONG: String literal instead of enum value
if $task/status = 'Completed' then

Fix: Use qualified enumeration value.

-- CORRECT: Module.Enumeration.Value
if $task/status = Module.TaskStatus.Completed then

</expression_errors>

<control_flow_errors>

"Activity cannot be the last object" (CE0105)

Problem: Missing RETURN statement.

-- WRONG: No RETURN
begin
  declare $Result boolean = true;
  log info 'Done';
  -- Missing RETURN!
end;

Fix: Add RETURN statement.

-- CORRECT
begin
  declare $Result boolean = true;
  log info 'Done';
  return $Result;
end;

"Action activity is unreachable" (CE0104)

Problem: Code after RETURN statement.

-- WRONG: Code after RETURN
if $value < 0 then
  return false;
  log info 'Negative';  -- Unreachable!
end if;

Fix: Move code before RETURN.

-- CORRECT
if $value < 0 then
  log info 'Negative';
  return false;
end if;

</control_flow_errors>

<syntax_errors>

Division operator

-- WRONG: Using / for division
set $average = $Total / $count;

-- CORRECT: Use 'div' keyword
set $average = $Total div $count;

Missing END IF / END LOOP

-- WRONG: Missing END IF
if $value > 0 then
  set $Positive = true;
-- Missing END IF!

-- CORRECT
if $value > 0 then
  set $Positive = true;
end if;

Missing semicolons

-- WRONG: Missing semicolon
declare $count integer = 0
set $count = 1

-- CORRECT
declare $count integer = 0;
set $count = 1;

</syntax_errors>

<reference_errors>

"Module not found"

Problem: Using non-existent module name.

Fix: Check module exists with show modules.

"Entity not found"

Problem: Using non-existent entity name.

Fix:

1. Check entity exists: show entities in ModuleName
2. Use fully qualified name: Module.EntityName

"Microflow not found"

Problem: Calling non-existent microflow.

Fix:

1. Check microflow exists: show microflows in ModuleName
2. Use fully qualified name: Module.MicroflowName

</reference_errors>

<error_code_reference>

Code	Message	Common Cause
CE0053	Selected type is not allowed	Missing AS for entity type
CE0104	Action activity is unreachable	Code after RETURN
CE0105	Must end with end event	Missing RETURN
CE0117	Error in expression	Unqualified association path
CW0094	Variable never used	Unused parameter/variable

</error_code_reference>

<quick_validation_checklist>

Before executing MDL:

• All entity types use declare $var as Module.Entity
• All SET targets have prior DECLARE
• Association paths are qualified: $var/Module.Assoc/attr
• Enum comparisons use Module.Enum.Value
• Every flow path ends with RETURN
• Division uses div not /
• All statements end with ;
• IF/LOOP properly closed with END IF/END LOOP

</quick_validation_checklist>

<output_rules>Output MDL code only in code blocks. Keep explanations concise.</output_rules>