Firebase Firestore 在文档删除失败时返回 true [英] Firebase Firestore returning true on failed document delete

问题描述

我有一个使用 Firebase 的 Firestore 进行持久化的应用.我正在使用 Material 的 Snackbar 进行通知.我有我的服务..

I have an app which uses Firebase's Firestore for persistence. I am using Material's Snackbar for notifications. I have in my service..

deleteProvider(data) {
    return this.db.collection(data.table).doc('xzc').delete();
  }

其中数据参数只是一个对象，其中包含我要对其执行操作的表和我要删除的文档的 ID.

Where the data param is simply an object containing the table which I want to perform the action on and the id of the document I wish to delete.

data: { table: 'providers', id: 'some firebase identifier'}

在我的组件中

onDeleteEntry(event) {
    if (event.table === 'providers') {
      this.providerService.deleteProvider(event)
        .then(() => {
          this.snackBar.open('Provider deleted');
        })
        .catch((error) => {
          this.snackBar.open('Error deleting provider', error);
        });
    }
  }

这完美地删除了文档，但在测试失败的情况时，它返回真.

This deletes the document perfectly, but on testing the failed case, it returns true.

例如，如果我将 'xyz' 硬编码到 .doc('xyz') 方法中.响应调用我的 next() 方法，而不是我的 catch().

For example, if I hard-code 'xyz' into the .doc('xyz') method. The response calls my next() method, rather than my my catch().

deleteProvider(data) {
    return this.db.collection(data.table).doc('xyz').delete();
  } // returns true on a non-existent document

Firebase 文档强调嵌套集合在删除后仍将保留的事实，但除此之外，删除文档的基本功能很简单，除了

The Firebase docs emphasise the fact that nested collections will remain after deletion but other than that, the basic functionality of deleting a document is simple and doesn't give very much information other than

db.collection("cities").doc("DC").delete().then(function() {
    console.log("Document successfully deleted!");
}).catch(function(error) {
    console.error("Error removing document: ", error);
});

我错过了什么?

TIA

推荐答案

目前，如果文档不存在，delete 不会不会失败.在某种程度上，这与 create 不一致，如果事先存在，它确实会失败.

Currently, delete does not fail if a document doesn't exist. In a way, this is inconsistent with create, which does fail if it exists beforehand.

但是，此功能似乎是/曾经计划的.在 Java SDK 中，delete 可以带一个 Precondition 对象:

However, it looks like this feature is/was planned. In Java SDK, delete can take a Precondition object:

  /**
   * Deletes the document referred to by this DocumentReference.
   *
   * @param options Preconditions to enforce for this delete.
   * @return An ApiFuture that will be resolved when the delete completes.
   */
  @Nonnull
  public ApiFuture<WriteResult> delete(@Nonnull Precondition options) {
    WriteBatch writeBatch = firestore.batch();
    return extractFirst(writeBatch.delete(this, options).commit());
  }

在Precondition中，有一个辅助方法:

In Precondition, there is a helper method:

  /**
   * Creates a Precondition that enforces that a document exists.
   *
   * @param exists Whether the document should exist.
   * @return A new Precondition
   */
  // TODO: Make public once backend supports verify.
  @Nonnull
  static Precondition exists(Boolean exists) {
    return new Precondition(exists, null);
  }

请注意，这不是公开的.评论说它缺乏后端支持.只有 Firestore 团队知道它的当前状态.

Note that is not public. The comment says it lacks backend support. Only Firestore team knows the current status of it.

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