mergeMap函数在Angular 5中给出错误

Question

错误：AngularFireObject <{}>无法分配为类型ObservableInput<{}>

这是示例功能代码

getAuthenticatedUserProfile(){

return this.auth.authState
    .map(user => user.uid)
    .mergeMap(authId => this.afDatabase.object('/profile/'+authId))
    .take(1)
}

Answer 1

mergeMap期望返回类型为ObservableInput<{}>的值。您正在呼叫this.afDatabase.object('/profile/'+authId)，这将返回AngularFireObject<{}>

调用valueChanges()会将其转换为可观察的：

return this.auth.authState
    .map(user => user.uid)
    .mergeMap(authId => this.afDatabase.object('/profile/'+authId).valueChanges())
    .take(1)
}