value property

E? value

Obtains the single E value of this relationship (null if not present).

Implementation

E? get value => _iterable.isNotEmpty ? _iterable.first : null;

void value=(E? newValue)

Sets the single E value of this relationship, replacing any previous value.

Passing in null will remove the existing value from the relationship.

Implementation

set value(E? newValue) {
  final isAddition = value == null && newValue != null;
  final isUpdate = value != null && newValue != null;
  final isRemoval = value != null && newValue == null;

  if (isRemoval || isUpdate) {
    super._remove(value!, notify: false);
  }
  if (isAddition || isUpdate) {
    super._add(newValue, notify: false);
  }

  // handle events
  DataGraphEventType? eventType;
  if (isAddition) eventType = DataGraphEventType.addEdge;
  if (isUpdate) eventType = DataGraphEventType.updateEdge;
  if (isRemoval) eventType = DataGraphEventType.removeEdge;

  if (eventType != null) {
    _graph._notify(
      [_ownerKey!, if (newValue != null) newValue._key!],
      metadata: _name,
      type: eventType,
    );
  }
  assert(_iterable.length <= 1);
}