我有以下课程：

import 'package:equatable/equatable.dart';
import 'package:objectbox/objectbox.dart';

@Entity()
/*
All fields of a class which extends Equatable should be immutable, but ObjectBox
requires the `id` field to be mutable because its value is set after an instance of
the class has been created.  Because of this, we ignore the linter rule
"must_be_immutable" on all ObjectBox entities.
*/
// ignore: must_be_immutable
class Foo extends Equatable {
  int id;
  final String fooProp;

  // I don't need a backlink yet, but very likely will in the future
  // @Backlink()
  // final ToMany<Bar> bars;

  Foo(
    this.fooProp,
    {
      this.id=0,
    }
  );

  @override
  List<Object> get props => [fooProp];
}

import 'package:equatable/equatable.dart';
import 'package:objectbox/objectbox.dart';

@Entity()
/*
All fields of a class which extends Equatable should be immutable, but ObjectBox
requires the `id` field to be mutable because its value is set after an instance of
the class has been created.  Because of this, we ignore the linter rule
"must_be_immutable" on all ObjectBox entities.
*/
// ignore: must_be_immutable
class Bar extends Equatable {
  int id;
  final String barProp;
  final ToMany<Foo> foos;

  Bar(
    this.barProp,
    this.foos,
    {
      this.id=0,
    }
  );

  @override
  List<Object> get props => [barProp, foos];
}

这就是我要做的

import 'package:foo_bar/objectbox/objectbox.dart';

// Get previously stored instance of Foo
Foo foo = ObjectBox.fooBox.get(1);

// Print foo.fooProp
print(foo.fooProp);  // Prints "asdf"

// Change foo.fooProp to something else
foo.fooProp = 'fdsa';

// Update foo
ObjectBox.fooBox.put(foo);

// Get the same instance of Foo again
foo = ObjectBox.fooBox.get(1);

// Check foo.fooProp to make sure it updated
print(foo.fooProp);  // Prints "fdsa", good so far

// Get previously stored instance of Bar which has Foo instance with ID of 1 in its foos
Bar bar = ObjectBox.barBox.get(1);

// Get our foo from bar.foos
foo = bar.foos[0];

// Verify the ID of foo to make sure it is the same object
print(foo.id);  // Prints "1", exactly what we expect

// Print foo.fooProp
print(foo.fooProp); // Prints "asdf", not the expected "fdsa"

该文件对这一问题作了如下说明：
请注意，to-many关系在第一次访问时被延迟解析，然后缓存在ToMany对象内的源实体中。因此，对任何方法（如ToMany对象的size（））的后续调用都不会查询数据库，即使关系在其他地方发生了更改。要获取最新数据，请再次获取源实体或在ToMany对象上调用reset（）。
reset()方法在ObjectBox的Flutter风格中似乎不可用，并且我们可以从我的示例中看到，即使获取ToMany关系的双方也不会导致预期的更新。
我错过了什么？

• • 失败的解决方法：**

我试着用下面这段糟糕的代码来解决这个问题，但即使这样也不起作用。ObjectBox完全忽略了实际的bar.foos，并且为foos持久化的内容仍然存在，不会更新。

final List<Bar> oldBars = ObjectBox.barBox.getAll();
List<Bar> newBars = [];
for(Bar oldBar in oldBars) {
  if(oldBar.foos.isNotEmpty) {
    List<int> oldFooIds = oldBar.foos.map((foo) => foo.id).toList();
    List<Foo> newFoos = foos.where((foo) => oldFooIds.contains(foo.id)).toList();
    Bar newBar = oldBar.copy(foos: ToMany<Foo>(items: newFoos));
    newBars.add(newBar);
  }
}

ObjectBox.barBox.putMany(newBars);

这让我觉得我的关系设置方式有问题，但是当ObjectBox生成器运行时没有错误

CALL flutter pub run build_runner build --delete-conflicting-outputs

• • 更新日期：**

我现在可以工作了，但是没有清理它。我设置了Bar构造函数来接受Foo对象的集合，但是传入Foo的示例是导致关系中断的原因。如果我创建Bar的示例，然后使用bar.foos.add(foo)，则结果与预期的一样。无论如何，这就是文档中的例子如何显示与关系的交互，我只是不认为它是字面上的，因为用这种方式创建新的对象是一件麻烦的事。我认为可以在构造函数中做一些工作，使事情变得更容易。