Qualify_GenericAt0() is an internal fallback operator that MDriven uses when bracket qualifier syntax [ ] is applied to an association that has no explicit Qualify implementation. It retrieves a single object by index position from a named role defined on the model root (SysSingleton / ECOModelRoot).

Important

This operator can only be called on the root class (SysSingleton). Calling it on any other class will throw: Second param must be a valid multilink name as string literal for class of root.

The second parameter must be the association role name as shown in the Roles panel of the OCL Editor not an attribute name.

Syntax

SysSingleton.allInstances.Qualify_GenericAt0( <index> , '<roleName>' )

Parameter	Type	Description
index	Int32	Zero-based position of the element to retrieve
roleName	String	Exact association role name defined on the root class

Example

First, link an object to the root via an Action:

SysSingleton.allInstances->first().ApiSearchResults->add(Articles1.allInstances->first())

Then retrieve it by index:

SysSingleton.allInstances.Qualify_GenericAt0( 0 ,'ApiSearchResults' )

This returns the Articles1 object at index 0 from the ApiSearchResults role on SysSingleton.

Preferred alternatives

-- Bracket syntax (recommended)

SysSingleton.allInstances->first().ApiSearchResults[0]

-- Standard OCL

SysSingleton.allInstances->first().ApiSearchResults->first()

Notes

• Returns null if the collection is empty or no object has been linked at runtime — even if instances of the target class exist independently
• The role name must match exactly what appears under Roles in the OCL Editor right panel when SysSingleton is selected
• Index is zero-based: 0 = first element