问题描述
ObjectBox 是否支持多个多对多关系 (M:N)? 例如:
// MIX with @Backlink and no @Backlink --> causes Error in this class
@Entity()
class Exercise {
int id;
String title;
String description;
final unitTypes = ToMany<UnitType>();
// Many To Many with Equipment
@Backlink()
final equipments = ToMany<Equipment>();
... Constructor etc.
}
// NO mix with @Backlink and no @Backlink --> no Error in this class
@Entity()
class UnitType{
int id;
String title;
@Backlink()
final exercises = ToMany<Exercises>();
@Backlink()
final units = ToMany<Unit>();
... Constructor etc.
}
@Entity()
class Unit{
int id;
String title;
String short;
final unitType = ToOne<UnitType>();
... Constructor etc.
}
就我的测试而言,我在一个类中使用多个多对多关系尝试的所有构建都失败了。抛出类似这样的错误:
Could not format because the source Could not be parsed:
line 1078,column 212 of .: Expected to find '}'.
╷
1078 │ toManyRelations: (Exercise object) => {RelInfo<Exercise>.toMany(27,object.id): object.unitTypesRelInfo<ExerciseEquipment>.toOneBacklink(3,object.id,(ExerciseEquipment srcObject) => srcObject.exercise): object.exerciseEquipments,
那么有没有办法在 ObjectBox 中完成这项工作,或者我是否必须使用另一个具有一对多关系的 Binder 类,例如在运动和 UnitType 之间 --> ExerciseUnitType (此解决方法对我有用,但并不美观,并且显着增加了对额外类和额外存储数据的需求)
@Entity()
class ExerciseUnitType{
int id;
String title;
@Backlink()
final exercise= ToOne<Exercise>();
@Backlink()
final unitType = ToOne<UnitType>();
... Constructor etc.
}
解决方法
could not format because the source could not be parsed:
line 1078,column 212 of .: Expected to find '}'.
╷
1078 │ toManyRelations: (Exercise object) => {RelInfo<Exercise>.toMany(27,object.id): object.unitTypesRelInfo<ExerciseEquipment>.toOneBacklink(3,object.id,(ExerciseEquipment srcObject) => srcObject.exercise): object.exerciseEquipments,
是 objectbox-generator 代码中的一个错误 - 它为您的配置创建了一个语法错误的代码(缺少逗号)。显然,在同一实体中同时拥有链接和反向链接并不是集成测试的一部分。我已经解决了这个问题,你可以更新你的 pubspec.yaml 以临时使用来自 github 的最新 objectbox-generator(使用 dependency_override
),或者等到修复在下一个 ObjectBox 版本中推出。要使用 Git 的固定版本:只需在 pubspec.yaml 的末尾添加以下代码
dependency_overrides:
objectbox_generator:
git:
url: https://github.com/objectbox/objectbox-dart.git
ref: 461a948439dcc42f3956b7d21b232eb9c2bc26e1
path: generator