如何获取带有 id 的特定文档数据?|AngularFire 5.1.1 |云防火墙 |文件 [英] How to get particular document data with id ? | AngularFire 5.1.1 | Cloud Firestore | Documents

问题描述

我正在使用数据访问服务从 firebase firestore 获取数据.

I am using Data access service to get the data from firebase firestore.

如何使用snapshotChanges()方法获取带有id的特定文档数据

How to use snapshotChanges()method for getting particular document data with id

getProduct(id: number): Observable<Product> {
    this.productsDocuments = this.angularfirestore.doc<Product>('products/' + id);
    this.product = this.productsDocuments.snapshotChanges().pipe(
      map(changes => changes.map(a => {
        const data = a.payload.doc.data() as Product;
        const id = a.payload.doc.id;
        return { id, ...data };
      }))
    );
    return this.product

我希望 this.product 返回文档值和文档 ID

I want this.product returns the document value and document id

谢谢！！

推荐答案

文档只是一个对象 {[field]: value}集合是文档[document]的容器.

A document is simply an object {[field]: value} and a collection is a container for documents [document].

您正在尝试获取单个文档/对象，但问题是您无法直接映射到它.我认为您想要获取整个集合，然后映射所有文档.

You are trying to get a single document/object and the problem is that you cannot map to it directly. I think that you want to get the entire collection, and then map over all of the documents.

getProduct(id: number): Observable<Product> {
    const productsDocuments = this.db.doc<Product>('products/' + id);
    return productsDocuments.snapshotChanges()
      .pipe(
        map(changes => {
          const data = changes.payload.data();
          const id = changes.payload.id;
          return { id, ...data };
        }))
  }

一个集合

getProduct(id: string): Observable<Product[]> {
    const productsDocuments = this.db.collection<Product[]>('products');
    return productsDocuments.snapshotChanges()
      .pipe(
        map(changes => changes.map(({ payload: { doc } }) => {
          const data = doc.data();
          const id = doc.id
          return { id, ...data };
        })),
        map((products) => products.find(doc => doc.id === id)))
  }

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