我在使用AngularFire2的Angular应用程序中有以下代码。
打字稿:
constructor(db: AngularFirestore) {
this.booksCollectionRef = db.collection<Book>('books');
this.books = this.booksCollectionRef.snapshotChanges().map(actions => {
return actions.map(action => {
const data = action.payload.doc.data() as Book;
const id = action.payload.doc.id;
return { id, ...data };
});
});
}
HTML:
<md-list>
<md-list-item *ngFor="let book of books | async">
<h4 md-line>{{book.name}}</h4>
</md-list-item>
</md-list>
此代码按预期检索和绑定数据(在更新集合时删除项目),现在我想按给定列对集合进行排序。我尝试使用firebase orderBy子句,但我无法弄清楚如何将其与snapShotChanges()
方法一起使用。
答案 0 :(得分:22)
以下内容适用于您的用例:
this.booksCollectionRef = db.collection<Book>('books', ref => ref.orderBy('order field'));
请查看documentation of AngularFirestore以获取有关此主题的更多信息。
答案 1 :(得分:5)
this.announcementCollectionRef = afs.collection<Announcement>('announcements', ref => ref.orderBy('createdAt', 'desc'));
this.announcements = this.announcementCollectionRef.snapshotChanges().map(actions => {
return actions.map(a => {
const data = a.payload.doc.data() as AnnouncementId;
const id = a.payload.doc.id;
return { id, ...data };
});
});
答案 2 :(得分:0)
不确定Angular Fire,但您可以尝试直接使用Firebase Firestore库。
以下代码适用于我:
someCollectionRef
.orderBy('columnName')
.onSnapshot((snapshot) => {
snapshot.docChanges.forEach(function (change) {
...doStuff