child_removed并不总是在firebase上开火-child_removeddoesn'talwaysfireonfirebase

I'm running two tests in firebase. One version passes, the other does not. The child_removed callback works fine if it's attached before the child is actually added. It does not fire when attached after the insert.

我在firebase中运行了两个测试。一个版本通过,另一个版本不通过。如果在实际添加子项之前附加了child_removed回调,则它可以正常工作。插入后连接时不会触发。

Version that passes the test:

通过测试的版本:

it("A) listens to child_removed raw (Before Insert)", function (done) {
  this.timeout(5000);

  let ref = DataServices.database.ref();
  let pushRef = ref.child('test/testChildRemovedA').push();
  let newKey = pushRef.key;
  let insertPath = 'test/testChildRemovedA/' + newKey;

  let callback = (snapshot) => { done(); }
  DataServices.database.ref('test/testChildRemovedA/').on("child_removed", callback);

  let updates = {};
  updates[insertPath] = 'hi';
  DataServices.database.ref().update(updates).then(() => {
      updates[insertPath] = null;
      DataServices.database.ref().update(updates);
    });
});

Version that fails the test:

未通过测试的版本:

it("B) listens to child_removed raw (After Insert)", function (done) {
  this.timeout(10000);

  let ref = DataServices.database.ref();
  let pushRef = ref.child('test/testChildRemovedB').push();
  let newKey = pushRef.key;
  let insertPath = 'test/testChildRemovedB/' + newKey;

  let callback = (snapshot) => { done(); }
  let updates = {};
  updates[insertPath] = 'hi';
  DataServices.database.ref().update(updates).then(() => {
      DataServices.database.ref('test/testChildRemovedB/').on("child_removed", callback);
      updates[insertPath] = null;
      DataServices.database.ref().update(updates);
    });
});

The only difference is where the child_removed event is attached, but both are attached before the data is actually deleted. In both cases, the data is indeed removed from firebase.

唯一的区别是附加了child_removed事件,但在实际删除数据之前都附加了这两个事件。在这两种情况下,确实从firebase中删除了数据。

Is there a race condition when adding the child_removed listener?

添加child_removed监听器时是否存在竞争条件?

1 个解决方案