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ISNULL

This function checks whether a value is unknown

Syntax

Code Block
ISNULL ( expression )
  • expression - Expression that is checked.

Return type

  • boolean - TRUE of the attribute is unknown, FALSE otherwise

Examples

Suppose the following data model.


 

Person.namePerson.SequenceNumber
“Bob”654
“Jane”?
Active PersonExpressionResultType
BobISNULL ( Person.SequenceNumber )FALSEBoolean
JaneISNULL ( Person.SequenceNumber )TRUEBoolean
 


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ISUNKNOWN

This function replaces a value if that value is unknown.

Syntax

Code Block
ISUNKNOWN ( expression , value )
  • expression- Expression of which the value has to be returned if that value is known.
  • value - Value to return if the attribute value is unknown.

Return type

  • any type, equals the attribute type

Examples

Suppose the following data model.

...


Person.namePerson.SequenceNumber
“Bob”654
“Jane”?
“Mary”667
“Rick”?
“Ron”?
“Jenny”765
?111
Active PersonExpressionResultType
Jane - ?ISUNKNOWN ( Person.SequenceNumber , 999 )999Integer
Mary - 667ISUNKNOWN ( Person.SequenceNumber , 999 )667Integer
? - 111ISUNKNOWN ( Person.Name , "customer" )"customer"String
UI Text Box
typenote

Both parameters of the ISUNKNOWN function must be of the same datatype. If they differ in datatype, you get this validation error in studio:

Could not find function: ISUNKNOWN matching arguments System.Collections.ArrayList

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IS A

Use this function to check the type of an instance. The function returns TRUE if the selected instance is of the specified entity.

Syntax

Code Block
instance IS A entity_name
  • instance - Instance to check.
  • entity_name - Name of the entity as string.

Return type

  • boolean

Examples

Suppose a domain model in which there is a singleton entity Residence that has a multivalued relation hasRooms with Room. Room is the base entity for singleton Kitchen and not singletons Bedroom and Bathroom.

If you want to determine the number of bedrooms is the residence:

  • COUNT ( COLLECT Room FROM Residence.hasRooms WHERE ( Room IS A “Bedroom” ) )

If you want to determine the number of bathrooms is the residence:

  • COUNT ( COLLECT Room FROM Residence.hasRooms WHERE ( Room IS A “Bathroom” ) )

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TYPE OF

Use this function to determine the type of an instance. The function returns the name of the entity.

Syntax

Code Block
TYPE OF base_entity
  • base_entity - Name of the instance's base entity.

Return type

  • string

Examples

Suppose a domain model in which there is a singleton entity Residence that has a multivalued relation hasRooms with Room. Room is the base entity for singleton Kitchen and not singletons Bedroom and Bathroom.

  • for the Kitchen instance the expression ( TYPE OF Room ) = “Kitchen”
  • for the Bedroom instances the expression ( TYPE OF Room ) = “Bedroom”

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ISACTIVE

Use this function to determine if an instance of a specific type is currently active.

Code Block
ISACTIVE instances [WHERE condition]
  • instances - instances to search
  • condition - optional condition to limit the collection of instances to check

Return type

  • boolean - TRUE if one of the instances is active, FALSE otherwise

    UI Text Box
    typenote

    Singletons are always active, so ISACTIVE <singleton> will always return TRUE 

Examples

Suppose the following data model.


 

instance_idPerson.namePerson.Age
Person_1“Bob”14
Person_2“Jane”25
Person_3“Mary”30
    
Active PersonExpressionResultTypeNote
NoneISACTIVE PersonFALSEBoolean
Person_1ISACTIVE PersonTRUEBoolean
Person_1ISACTIVE Person WHERE Person.Age >= 18FALSEBoolean
NoneISACTIVE systemTRUEBoolean
NonePerson.Age >= 18Error 
No Person is active
None( ISACTIVE Person ) AND Person.Age >= 18FALSEBooleanThe expression is evaluated left-to-right and fails on ( ISACTIVE Person ) instead of giving an error
 



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GUID

This function is able to generate a globally unique identifier which can later be used to uniquely mark and recognize a desired element.

The GUIDs are represented as 32 hexadecimal digits, displayed in five groups separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters.

 


Syntax

Code Block
GUID()

Return type

  • String - the generated GUID

Examples

 


ExpressionResult
GUID()4a18d6a7-03c1-47f9-b6aa-eae7d746050e
GUID()91d37298-23ec-4bd4-8523-9c7e7745cb9d

 

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