Necessary modifications to the IFC schema

In order for the IFC schema to work with EdgeDB, a few modifications were made to certain element types and specific elements/relationships of elements.

Base Types

All IFC schema objects that are wrapping base types only (i.e. string, float, integers, etc..) are replaced by their respective base types. I.e. IfcLabel is never instantiated, rather it is stored as a string.

Take an arbitrarily chosen class IfcQuantityArea which points to the IFC built-in types IfcAreaMeasure & IfcLabel.

ENTITY IfcQuantityArea
 SUBTYPE OF (IfcPhysicalSimpleQuantity);
	AreaValue : IfcAreaMeasure;
	Formula : OPTIONAL IfcLabel;
 WHERE
	WR21 : NOT(EXISTS(SELF\IfcPhysicalSimpleQuantity.Unit)) OR
   (SELF\IfcPhysicalSimpleQuantity.Unit.UnitType = IfcUnitEnum.AREAUNIT);
	WR22 : AreaValue >= 0.;
END_ENTITY;

These built-in types are in practice a float and string

TYPE IfcAreaMeasure = REAL;
END_TYPE;

TYPE IfcLabel = STRING(255);
END_TYPE;

Consequently, in the EdgeDB ESDL schema declaration, these IFC built-in types are replaced by the native types float and str as shown here

type IfcQuantityArea extending IfcPhysicalSimpleQuantity {
    required property AreaValue -> float64;
    property Formula -> str;
}

Note

For any constraints associated with these base IFC classes, it is possible to assert them directly to the ESDL property statements.

This means, that if the IfcLabel string limit must be enforced, it is possible to do so using the EdgeDB built-in constraint expression and the max_len_value function

type IfcQuantityArea extending IfcPhysicalSimpleQuantity {
    required property AreaValue -> float64;
    property Formula -> str {
        constraint max_len_value(255);
    };
}

Potential improvements

IfcPerson - Make Identification unique

    type IfcPerson  {
        property Identification -> str {
            constraint exclusive;
        }
        property FamilyName -> str;
        property GivenName -> str;
        property MiddleNames -> tuple<str>;
        property PrefixTitles -> tuple<str>;
        property SuffixTitles -> tuple<str>;
        multi link Roles -> IfcActorRole;
        multi link Addresses -> IfcAddress;
    }