Question

我有下面的代码段在Angular 6中不起作用。编译器显示错误，因为内部map函数的类型为“ {}”的属性“ map”不存在”。有人可以指导我如何从快照更改中获取有效负载和ID。

代码：

this.postCollection.snapshotChanges().pipe(
      map(actions => actions.map(a => {      //this inner map throws error >Property 'map' does not exist on type '{}'
        const data = a.payload.doc.data() as Post;
        const id = a.payload.doc.id;
        return { id, ...data };
      }))
    );

依赖性：

"dependencies": {
    "@angular/animations": "^6.0.0",
    "@angular/cdk": "^6.3.1",
    "@angular/common": "^6.0.0",
    "@angular/compiler": "^6.0.0",
    "@angular/core": "^6.0.0",
    "@angular/forms": "^6.0.0",
    "@angular/http": "^6.0.0",
    "@angular/material": "^6.3.1",
    "@angular/platform-browser": "^6.0.0",
    "@angular/platform-browser-dynamic": "^6.0.0",
    "@angular/router": "^6.0.0",
    "angularfire2": "^5.0.0-rc.11",
    "core-js": "^2.5.4",
    "firebase": "^5.1.0",
    "rxjs": "^6.0.0",
    "zone.js": "^0.8.26"
  },

谢谢。

Answer 1

编辑真实答案

我发现了问题。您需要将postCollection声明为AngularFirestoreCollection。这是我为下面的代码所做的操作：

    updatedb: AngularFirestoreCollection<item>;

然后我可以使用它而不会出现地图错误。希望这会有所帮助！

过去（可行，但不是最好的）答案

我遇到了同样的问题。我认为这与您的postCollection变量有关。当我把完整的db.collection ...调用放到那里时，它对我有用。不确定是否声明该变量（我只是将我作为通用变量，未分配在文件顶部。

这不起作用：

export class DataService {

items$: Observable<any>;
selectedItem$: Observable<any>;
selected3x3: item = new item();
timeout;
email: string;
updatedb;

get3x3s(){
    if(!this.email){
        this.items$ = this.updatedb.snapshotChanges().pipe(
            map(changes => {
                return changes.map(doc => {
                    return{
                        id: doc.payload.doc.id,
                        data: doc.payload.doc.data()
                    }
                })
            })
        );

但这确实可以编译：

export class DataService {

items$: Observable<any>;
selectedItem$: Observable<any>;
selected3x3: item = new item();
timeout;
email: string;
updatedb;

get3x3s(){
    if(!this.email){
        this.items$ = this.db.collection(this.email).snapshotChanges().pipe(
            map(changes => {
                return changes.map(doc => {
                    return{
                        id: doc.payload.doc.id,
                        data: doc.payload.doc.data()
                    }
                })
            })
        );

Answer 2

解决方案：

this.afStore.collection(`${uid}/ingresos-egresos/items`)
    .snapshotChanges()
    .pipe(
      map(docData => {
        return docData.map( doc => {
          let data = doc.payload.doc.data() as IngresoEgreso; //here solutions
          return {
            uid: doc.payload.doc.id,
            ...data
          };
        });
      })
    )
    .subscribe(docData => {
      console.log(docData);                  
    });

如何从角度6中的snapshotChanges获取有效负载和文档ID？

2 个答案: