How to get particular document data with id ? | AngularFire 5.1.1 | Cloud Firestore | Documents

Question

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

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

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

Thank You!!

Answer 1

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

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 };
        }))
  }

for a collection

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)))
  }