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DataClassAttribute

Dataclass attributes are available as properties of their respective classes. Par exemple :

 nameAttribute:=ds.Company.name //référence à un attribut de classe
 revenuesAttribute:=ds.Company["revenues"] //méthode alternative

This code assigns to nameAttribute and revenuesAttribute references to the name and revenues attributes of the Company class. Cette syntaxe ne retourne PAS les valeurs contenues dans l'attribut, mais retourne plutôt des références aux attributs eux-mêmes. To handle values, you need to go through Entities.

DataClassAttribute objects have properties that you can read to get information about your dataclass attributes.

Dataclass attribute objects can be modified, but the underlying database structure will not be altered.

Sommaire

.autoFilled : Booléen     contains True if the attribute value is automatically filled by 4D
.fieldNumber : Entier     contains the internal 4D field number of the attribute
.fieldType : Integer     contains the 4D database type of the attribute
.indexed : Booléen     contains True if there is a B-tree or a Cluster B-tree index on the attribute
.inverseName : Text     returns the name of the attribute which is at the other side of the relation
.keyWordIndexed : Boolean     contains True if there is a keyword index on the attribute
.kind : Text     returns the category of the attribute
.mandatory : Boolean     contains True if Null value input is rejected for the attribute
.name : Text     retourne le nom de l'objet dataClassAttribute en chaîne
.relatedDataClass : Text     retourne le nom de la dataclass associée à l'attribut
.type : Texte     contient le type de valeur conceptuelle de l'attribut
.unique : Booléen     contient True si la valeur d'attribut doit être unique

.autoFilled

Historique

Version	Modifications
v17 R5	Ajoutées

.autoFilled : Booléen

Description

The .autoFilled property contains True if the attribute value is automatically filled by 4D. This property corresponds to the following 4D field properties:

• "Autoincrement", for numeric type fields
• "Auto UUID", for UUID (alpha type) fields.

This property is not returned if .kind = "relatedEntity" or "relatedEntities".

For generic programming, you can use Bool(dataClassAttribute.autoFilled) to get a valid value (false) even if .autoFilled is not returned.

.fieldNumber

Historique

Version	Modifications
v17 R5	Ajoutées

.fieldNumber : Entier

Description

The .fieldNumber property contains the internal 4D field number of the attribute.

This property is not returned if .kind = "relatedEntity" or "relatedEntities".

For generic programming, you can use Num(dataClassAttribute.fieldNumber) to get a valid value (0) even if .fieldNumber is not returned.

.fieldType

Historique

Version	Modifications
v17 R5	Ajoutées

.fieldType : Integer

Description

The .fieldType property contains the 4D database type of the attribute. It depends on the attribute kind (see .kind).

Valeurs possibles :

dataClassAttribute.kind	fieldType	Commentaire
storage	Corresponding 4D field type	Voir la commande Type
relatedEntity	38 (Is object)
relatedEntities	42 (Is collection)

.indexed

Historique

Version	Modifications
v17 R5	Ajoutées

.indexed : Booléen

Description

The .indexed property contains True if there is a B-tree or a Cluster B-tree index on the attribute.

This property is not returned if .kind = "relatedEntity" or "relatedEntities".

For generic programming, you can use Bool(dataClassAttribute.indexed) to get a valid value (false) even if .indexed is not returned.

.inverseName

Historique

Version	Modifications
v17 R5	Ajoutées

.inverseName : Text

Description

The .inverseName property returns the name of the attribute which is at the other side of the relation.

This property is not returned if .kind = "storage". It must be of the "relatedEntity" or "relatedEntities" kind.

For generic programming, you can use String(dataClassAttribute.inverseName) to get a valid value ("") even if .inverseName is not returned.

.keyWordIndexed

Historique

Version	Modifications
v17 R5	Ajoutées

.keyWordIndexed : Boolean

Description

The .keyWordIndexed property contains True if there is a keyword index on the attribute.

This property is not returned if .kind = "relatedEntity" or "relatedEntities".

For generic programming, you can use Bool(dataClassAttribute.keyWordIndexed) to get a valid value (false) even if .keyWordIndexed is not returned.

.kind

Historique

Version	Modifications
v17 R5	Ajoutées

.kind : Text

Description

The .kind property returns the category of the attribute. Returned value can be one of the following:

• "storage": storage (or scalar) attribute, i.e. attribute storing a value, not a reference to another attribute
• "relatedEntity": N -> 1 relation attribute (reference to an entity)
• "relatedEntities": 1 -> N relation attribute (reference to an entity selection)

Exemple

Given the following table and relation:

 var $attKind : Text
 $attKind:=ds.Employee.lastname.kind //$attKind="storage"
 $attKind:=ds.Employee.manager.kind //$attKind="relatedEntity"
 $attKind:=ds.Employee.directReports.kind //$attKind="relatedEntities"

.mandatory

Historique

Version	Modifications
v17 R5	Ajoutées

.mandatory : Boolean

Description

The .mandatory property contains True if Null value input is rejected for the attribute.

This property is not returned if .kind = "relatedEntity" or "relatedEntities".

For generic programming, you can use Bool(dataClassAttribute.mandatory) to get a valid value (false) even if .mandatory is not returned. Warning: This property corresponds to the "Reject NULL value input" field property at the 4D database level. It is unrelated to the existing "Mandatory" property which is a data entry control option for a table.

.name

Historique

Version	Modifications
v17 R5	Ajoutées

.name : Text

Description

La propriété .name retourne le nom de l'objet dataClassAttribute en chaîne.

Exemple

 var $attName : Text
 $attName:=ds.Employee.lastname.name //$attName="lastname"

.relatedDataClass

Historique

Version	Modifications
v17 R5	Ajoutées

.relatedDataClass : Text

Description

Cette propriété n'est disponible qu'avec les attributs de la propriété "relatedEntity" ou "relatedEntities" .kind.

La propriété .relatedDataClass retourne le nom de la dataclass associée à l'attribut.

Exemple

Considérons les tableaux et relations suivants :

 var $relClass1; $relClassN : Text
 $relClass1:=ds.Employee.employer.relatedDataClass //$relClass1="Company"
 $relClassN:=ds.Employee.directReports.relatedDataClass //$relClassN="Employee"

.type

Historique

Version	Modifications
v17 R5	Ajoutées

.type : Texte

Description

La propriété .type contient le type de valeur conceptuelle de l'attribut, utile pour la programmation générique.

Le type de valeur conceptuelle dépend de l'attribut .kind.

Valeurs possibles :

dataClassAttribute.kind	type	Commentaire
storage	"number", "date", "object", "bool", "image", ou "string"	"nombre" est rertourné pour tous les types numériques, y compris la durée. "string" est retourné pour les types de champs uuid, alpha et text
relatedEntity	nom de dataClass associé	Ex : "Companies"
relatedEntities	nom de dataClass associé + suffixe "Selection"	Ex : "EmployeeSelection"

.unique

Historique

Version	Modifications
v17 R5	Ajoutées

.unique : Booléen

Description

La propriété .unique contient True si la valeur d'attribut doit être unique. Cette propriété correspond à la propriété de champ 4D "Unique".

This property is not returned if .kind = "relatedEntity" or "relatedEntities".

Pour la programmation générique, vous pouvez utiliser Bool (dataClassAttribute.unique) pour obtenir une valeur valide (false) même si .unique n'est pas retourné.