我试图检索给定documentID的文档字段值。我已经解决了db调用部分，但无法将数据发送回去。就好像下面的函数this.userDbService.getVendorNameFromUserId根本没有被调用一样。
下面是父函数：

async getVendorName() {
  let name;

  //blindtiger not going here.

  //calling to 'private userDbService: UserDbService'
   name = await this.userDbService.getVendorNameFromUserId('2OD1yTnMrecMgqljvHFHDjug1VT2');
   console.log(name);
   return name.toString();}

下面是函数getVendorNameFromUserId（''）：

async getVendorNameFromUserId(id: string): Promise<string> {
    let vendorName = '';
    const userCollectionRef = await doc(this.store, 'clients/' + id);

    await docData(userCollectionRef, {idField: 'id'}).forEach(el => {

      //correctly is 'blindtiger' from db call.
      console.log(el['user'].companyName.toString())
      return el['user'].companyName.toString();
    });
    //parent function doesn't yield any results - as if this is not called.
    // It should yield 'blindtiger' here.
    return 'NOT FOUND';
  }

getVendorName（）是在一个类型脚本文件的构造函数中调用的，这个函数结果的值将用于获取该供应商名称的所有产品。

constructor(private shopifyService: ShopifyService, private userDbService: UserDbService, private modalService: NgbModal, private userAuthService: UserAuthService, private itemDb: ItemDbService) {
    let vendorName: string;

    const name = this.getVendorName();
    console.log(name);
    this.getAllProducts(name).then(result => {
      console.log(result);
      this.itemsToSell = result;
    });
  }`

我有一种感觉，我错过了一些与异步相关的东西-- buy会喜欢任何关于为什么“blindtiger”的价值甚至没有被传递到链上的建议。
我尝试过在函数调用- getVendorNameFromUserId（）中添加异步等待，如果我在docData（）的from中删除了等待关键字：

await docData(userCollectionRef, {idField: 'id'}).forEach(el => {

      //correctly is 'blindtiger' from db call.
      console.log(el['user'].companyName.toString())
      return el['user'].companyName.toString();
    });`

我得到的结果是'NOT FOUND' --这意味着它正确地将数据向上传递。我认为调用函数没有等待这个函数是有问题的，看起来像这样：

async getVendorName() {
    let name;

    //blindtiger not going here.

    //calling to 'private userDbService: UserDbService'
    name = await this.userDbService.getVendorNameFromUserId('2OD1yTnMrecMgqljvHFHDjug1VT2');
    console.log(name);
    return name.toString();
  }

docData返回一个可观察对象。

const data = await docData(userCollectionRef, {idField: 'id'}).pipe(take(1)).subscribe(user => {
  vendorName = user['user'].companyName;

  //does not yield blind tiger
  console.log({dataDone: vendorName});
})

//does yield blind tiger
console.log({dataAfter: vendorName})
return vendorName['user'].companyName

}