Attributes

The IFC schema differentiates between attributes, directly attached to an object, and properties, grouped in a propertyset and assigned to the object by a number of relations. Height and width are attributes, directly related to a door and not difficult to retrieve.

Select ?Var1
Where ?Var1.Attribute.GlobalId = “87d87dffn47a90z”
Select ?Var2 := ?Var1.Attribute.OverallHeight

Properties

A material is a property and not directly related to the object. To find the material of a door not one, but multiple nodes need to be past first. To find a property BimQL can be used.

Select ?Var1
Where ?Var1.Attribute.GlobalId = “87d87dffn47a90z”
Select ?Var2 := ?Var1.Attribute.IsDefinedBy
Select ?Var3 := ?Var2.Attribute.RelatingPropertyDefinition
Select ?Var4 := ?Var3.Attribute.HasProperties
Where ?Var1.Attribute.Name = “Material”
Select ?Var5 := ?Var4.Attribute.NominalValue

Query shortcut

The example above can be used to retrieve a property, however it is not very user-friendly. Therefore a query shortcut was introduced to streamline this process.

Select ?Var1
Where ?Var1.Attribute.GlobalId = “87d87dffn47a90z”
Select ?Var2 := ?Var1.Property.Material