我正在构建一个使用Firebase和AngularFire2(目前处于alpha版)的实验性(Ionic 2)应用程序.为此,我将遵循Aaron Saunders的教程作为基础：
http://www.clearlyinnovative.com/integrating-firebase-with-angularfire2-into-angular2-ionic2-part-2
https://github.com/aaronksaunders/ionic2-angularfire-sample
以下是我的home.ts和我的home.html.
this.projects = af.list('/items').map( (items) => {
return items.map( item => {
item.Meta = af.object(`/item_Meta/${item.$key}`)
return item
})
})
这种通过AngularFire2嵌套Observables返回的方式在以下演示中得到了证明：https://youtu.be/ngnSOTSS8Q8?t=1h6m37s
这是我的观点：
<ion-card *ngFor="#item of items | async">
<ion-card-header>
{{item.name}}
</ion-card-header>
<ion-card-content>
{{item.description}}
<br>
{{item.Meta.stockPrice | async}}
</ion-card-content>
</ion-card>
与我所遵循的演示中的示例的主要区别在于,我在’list / array’Observable中嵌套了一个’对象’Observable.相反,他们在列表中添加一个列表.这样做的结果是我试图直接在我的视图中渲染{{item.Meta.stockPrice}}而不是嵌套ngFor.
这就是我的数据：
{
"items":
{
"item1":{
"name": "Item 1","description": "1234"
},"item2":{
"name": "Item 2","description": "abcd"
}
}
"items_Meta"{
"item1":{
"stockPrice": 1234,"moarData": "derp"
},"item2":{
"stockPrice": 386,"moarData": "lolz"
}
}
}
我似乎无法弄清楚为什么对象不想渲染.如果我将它输出到JSON,它会显示数据存在.请注意,我是Angular2的新手,仍然围绕着Angular1的变化.我究竟做错了什么？
编辑：我已更新上面的信息并添加了我的数据结构,以使其更清晰
针对您的具体问题……
原文链接：https://www.f2er.com/angularjs/140948.html{{(item.Meta | async)?.stockPrice}}
使用elvis运算符(？)确保异步操作完成,然后访问所需的值
这里的源代码是github：https://github.com/aaronksaunders/afwithngcli
–
script.html
</ion-card>
<ion-card *ngFor="#user of usersWithMessages | async">
<ion-card-header>
{{user.displayName}}
</ion-card-header>
<ion-card-content>
{{ (user.messages | async) | json}}
</ion-card-content>
</ion-card>
script.ts
this.usersWithMessages = this.af.list('/users').map((_users) => {
return _users.map((_user) => {
_user.messages = this.af.object("/userObjects/public-messages/" +_user.$key)
return _user
})
})
数据
"userObjects" : {
"public-messages" : {
"8d75a63e-80cd-40cc-8f8b-87d3d33b0cd0" : {
"message-id-0" : {
"text" : "a public message"
}
},"9c6ea912-ec24-4127-b123-6512ed135f06" : {
"-KFCGp5ojo7JSX2myOPE" : {
"date" : "1460511658442.75","text" : "this should be a. public message"
},"-KFCJc4GtEo_PDWi7hru" : {
"date" : "1460512391529.69","text" : "this is a message that should be public"
},"message-id-100" : {
"date" : "3243245411111","text" : "public for the other user"
}
}
}
},"users" : {
"8d75a63e-80cd-40cc-8f8b-87d3d33b0cd0" : {
"displayName" : "c@mail.com","provider" : "password"
},"9c6ea912-ec24-4127-b123-6512ed135f06" : {
"displayName" : "b@mail.com","cdcf32af-a8cd-467d-a04f-dfc223e890d2" : {
"avatar" : "https://secure.gravatar.com/avatar/d23563ab3014ce965a90c37b22a34da8?d=retro","displayName" : "bryce@mail.com","provider" : 4
}
}
