Is it possible to query by backlink relation?


I have 2 classes set up with these relations, with Faults only having 1 equipment, and equipment having many faults.

class Equipment {
  int? id;
  String adminNumber;

  final faults = ToMany<Fault>();

class Fault {
  /// Let objectbox handle ID assigning
  int? id;
  String uuid;

  final equipment = ToOne<Equipment>();

I’m attempting to utilize the backlink to find all equipment that has a connection to a fault, (as equipment can be created without a fault).

But I can’t seem to access the faults property of the equipment

final testQuery = _localDbBaseService.faultsBox.query()
  ..backlink(Equipment_.faults, Equipment_.faults.notNull());
final test =;

return test;

"The getter ‘faults’ isn’t defined for the type ‘Equipment_’."

I’m pretty sure I have the query backward, but I’m just attempting to figure out how to correctly use backlink. I know I could walk through this forward by querying all faults and then querying all equipment and filtering them like that, but I feel as if backlink should function this way….or am I completely misunderstanding its intention? I can’t seem to find many examples relating to Backlinks, especially with in Dart


Oh man, the rubber ducky method helps again, I feel like an idiot. Anyway, for anyone else that stumbles upon this working with backlinks in flutter, you do indeed query the "parent" object

final builder = _localDbBaseService.equipmentBox
final query =;
final items = query.find();

return items;

Answered By – Swisscheese

Answer Checked By – Robin (FlutterFixes Admin)

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