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我有以下功能是服务提供者。我想分开保留后端和UI部分,因此我使用提供程序来提取所有数据。Apollo Angular2客户端处理承诺
getUserById(id: number) {
return new Promise((resolve, reject) => {
this.apollo.query({
query: UserByIdQueryText,
variables: {
id: id
}
}).subscribe((res: any) => {
let ans = res.data.user;
if (ans) {
console.log(ans);
resolve(ans);
} else {
reject('could not get user');
}
}, (err) => {
console.error(err);
});
});
}
在实际的页面,我有下面的代码来获取数据。
export class UserProfilePage {
public user: User;
public id: number;
constructor(private userService: UserService, private navController: NavController, private params: NavParams) {
this.user = null;
this.id = params.get("id");
this.userService.getUserById(this.id)
.then((user: User) => {
this.user = user;
});
}
}
问题是远程调用迟到,但视图试图显示数据。我得到下面的错误。
Error: Uncaught (in promise): TypeError: Cannot read property 'title' of null
TypeError: Cannot read property 'title' of null
at Object.eval [as updateRenderer] (ng:///AppModule/UserProfilePage.ngfactory.js:273:28)
at Object.debugUpdateRenderer [as updateRenderer] (http://localhost:8100/build/main.js:12978:21)
at checkAndUpdateView (http://localhost:8100/build/main.js:12357:14)
at callViewAction (http://localhost:8100/build/main.js:12667:17)
at execComponentViewsAction (http://localhost:8100/build/main.js:12613:13)
我正在使用与GraphQL后端数据相关的Apollo客户端。我想用Apollo来获取数据... – Purus