You are viewing the documentation for Blueriq 16. Documentation for other versions is available in our documentation directory.

Learn more about the functions ISNULL, ISUNKNOWN, IFUNKNOWN, IS A, TYPE OF, ISACTIVE, GUID. 

Overview 

FunctionDescription
ISNULLChecks whether a value is unknown. 
ISUNKNOWNReplaces a value if that value is unknown.
IFUNKNOWNAlternative notation of the ISUNKNOWN function, which increases readability especially for long expressions.
IS AChecks the entity type of an instance.
TYPE OFDetermines the entity type of an instance.
ISACTIVEDetermines if an instance of a specific entity type is currently active.
GUIDGenerates a globally unique identifier which can later be used to uniquely mark and recognize a desired element. 

Functions

ISNULL


Checks whether a value is unknown. 


Syntax

ISNULL ( expression )



Input
  • 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


Replaces a value if that value is unknown.


Syntax

ISUNKNOWN ( expression , value )



Inputs
  • expression- Expression of which the value has to be returned if that value is known.
  • value - Value to return if the expression value is unknown.


Return type

  • any type, equals the expression 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


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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IFUNKNOWN


Alternative notation of the ISUNKNOWN function, which increases readability especially for long expressions. This function replaces a value if that value is unknown.


The IFUNKNOWN function takes precedence over any other binary operator (except for the "NOT" operator). For example, this means that the expression A.B AND C.D IFUNKNOWN FALSE will be interpreted as A.B AND (C.D IFUNKNOWN FALSE). You can use parentheses to influence this behavior, e.g. by writing (A.B AND C.D) IFUNKNOWN FALSE. For the "NOT" operator the following expression "X AND NOT B IFUNKNOWN FALSE", can also be read as "X AND ((NOT B) IFUNKNOWN FALSE)"


Syntax

expression IFUNKNOWN value


Inputs

  • expression- Expression of which the value has to be returned if that value is known.

  • value - Value to return if the expression value is unknown.


Return type

  • any type, equals the expression type


Examples

Suppose the following data model.


Person.namePerson.SequenceNumberPerson.HasDrivingLicense
“Bob”654true
“Jane”?true
“Mary”667false
“Rick”??
“Ron”?false
“Jenny”765true
?111true
Active PersonExpressionResultType
Jane - ? - truePerson.SequenceNumber IFUNKNOWN 999 999Integer
Mary - 667 - falsePerson.SequenceNumber IFUNKNOWN 999667Integer
? - 111 - truePerson.Name IFUNKNOWN "customer""customer"String
"Rick" - ? - ?NOT Person.HasDrivingLicense IFUNKNOWN falsefalseBoolean

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

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

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IS A


Checks the entity type of an instance. The function returns TRUE if the selected instance is of the specified entity. 


Syntax

instance IS A entity_name



Inputs
  • 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


Determines the entity type of an instance. The function returns the name of the entity.


Syntax

TYPE OF base_entity


Input

  • 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


Determines if an instance of a specific entity type is currently active.


ISACTIVE instances [WHERE condition]


Inputs

  • 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

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


Generates 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

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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3 Comments

  1. Ronald Peterson

    Jul 11, 2018

    What is the best use of the GUID function? Should I make an attribute userset with the result?

    1. Unknown User (m.schadd)

      Feb 15, 2021

      Ronald Peterson Well that depends. The trueth maintenance mechanism will not create a new guid unless something else in the expression changes (e.g., system.currentPage + GUID(), which is discouraged). So as long as your session is alive, the guid stays the same. In case that you send the guid to an external service, the external service can store and use the guid. In case you want to store the guid value in an aggregate, then you might want to make it user-set. As only user-set values are stored in an aggregate, you would get a new guid when reading the aggregate. In case this is not desired, you should make the attribute user set first (using the Service call type: AQ_Instance_Update). This is similar to the consideration when using NOW or TODAY.

  2. Pieter Lubbers

    Aug 08, 2018

    Can you confirm that the ISACTIVE function works the same as a reusable expression? That is: without context.

    I tried the following function (in a repeat box on a container) without success:
    COLLECT A FROM ALL A WHERE( ISACTIVE( B ) AND A.isTrue)
    The error states: ALIAS must be specified for each/exists/isactive expressions when the from type is not of entity time.

    I recall that the following reusable expression doesn't work with the same error:
    {RE} = A.isTRUE
    COLLECT A FROM ALL A WHERE( A.Number = COLLECT B FROM ALL B WHERE( {RE} AND B.Number = A.Number)

     

    Or more simply:

    {RE} = ISACTIVE(A)  → Works
    {RE} = ISACTIVE(A) AND TRUE  → Error

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