Code examples

These examples assume an initialized runtime and an open model, as in Hello, world!. They use the entity graph directly, including forward and inverse attributes.

Get all entities

model.ids lists the STEP ids in ascending order:

for (const id of model.ids) {
  const entity = model.byId(id);
  {
    if (!entity) continue;
    console.log(entity.id(), entity.isA());
    if (entity.attributes().includes('Name')) console.log(entity.get('Name'));
  }
}

Get all wall types

const types = model.byType('IfcWallType');
{
  for (const type of types) console.log(type.id(), type.get('Name'));
}

Find the type of an occurrence

An IFC4 occurrence refers to its type through IsTypedBy. Follow the relationship and read its RelatingType:

const walls = model.byType('IfcWall');
{
  for (const wall of walls) {
    const relations = wall.inverse('IsTypedBy');
    {
      for (const relation of relations) {
        const type = relation.get('RelatingType');
        if (type instanceof ifcopenshell.EntityInstance) {
          {
            console.log(wall.get('Name'), type.get('Name'));
          }
        }
      }
    }
  }
}

For IFC2X3, type relationships are among IsDefinedBy; select those whose class is IfcRelDefinesByType.

Find the spatial container of an element

The following finds the immediate containment relationship. An element can also inherit containment through an aggregate, which requires following its Decomposes relationships.

const walls = model.byType('IfcWall');
{
  for (const wall of walls) {
    const relations = wall.inverse('ContainedInStructure');
    {
      for (const relation of relations) {
        const container = relation.get('RelatingStructure');
        if (container instanceof ifcopenshell.EntityInstance) {
          {
            console.log(wall.id(), container.isA(), container.get('Name'));
          }
        }
      }
    }
  }
}

Read property sets

For occurrence property sets, follow IfcRelDefinesByProperties from IsDefinedBy. This example reads single-value properties; quantities, complex properties, and type-level property sets have their own IFC attributes.

const walls = model.byType('IfcWall');
{
  for (const wall of walls) {
    const relations = wall.inverse('IsDefinedBy');
    {
      for (const relation of relations) {
        if (!relation.isA('IfcRelDefinesByProperties')) continue;
        const pset = relation.get('RelatingPropertyDefinition');
        if (!(pset instanceof ifcopenshell.EntityInstance)) continue;
        {
          if (!pset.isA('IfcPropertySet')) continue;
          const properties = pset.get('HasProperties');
          if (!Array.isArray(properties)) continue;
          try {
            for (const property of properties) {
              if (!(property instanceof ifcopenshell.EntityInstance)) continue;
              if (!property.isA('IfcPropertySingleValue')) continue;
              const value = property.get('NominalValue');
              {
                console.log(pset.get('Name'), property.get('Name'),
                  value instanceof ifcopenshell.EntityInstance ? value.get(0) : value);
              }
            }
          } finally {
            for (const property of properties) {
            }
          }
        }
      }
    }
  }
}

Navigate references

model.getInverse(entity) returns a set of referring entities, deduplicated by IFC identity. model.traverse(entity, maxDepth) follows forward references; use -1 for unlimited depth or traverseBreadthFirst for breadth-first order. Traversal returns an ordinary JavaScript array.

const entity = model.byId(model.ids[0]);
{
  if (entity) {
    const referring = [...model.getInverse(entity)];
    const referenced = model.traverse(entity, 1);
    {
      console.log('Referenced by:', referring.map(item => item.id()));
      console.log('Forward traversal:', referenced.map(item => item.id()));
    }
  }
}

Query units

getUnit() returns the unit magnitude for a unit type. For example, a millimetre-based model has a length magnitude of 0.001 relative to metres:

console.log(model.getUnit('LENGTHUNIT'));

See Geometry processing for extracting transformed geometry and Schema querying for querying attribute declarations.