Angular 2在引导之前从服务器获取配置

问题描述

我需要在应用程序引导之前从服务器获取配置.我可以在主要ngModule的提供程序中使用此功能:

I need to get configuration from server before the application bootstraps. I was able to do that using this in providers in my main ngModule:

{
    provide: APP_INITIALIZER,
    useFactory: (links: Links) => () => links.init(),
    deps: [Links, Http],
    multi: true
}

链接服务:

init(): Promise<any> {
    var observable = this.http.get('someUrl').map(res => res.json());
    observable.subscribe(res => {
        this.config = res;
    });
    return observable.toPromise();
}

此代码在应用程序引导之前执行，但是直到我的应用程序请求Links.config后，服务器的响应才会出现.在Promise解决之后，我如何强制应用程序不进行引导?我尝试了promise.resolve()，但没有帮助.

This code gets executed before the application bootstraps, but the response from server is not present until after my app asks for Links.config. How do I force the app to not bootstrap until after the Promise gets resolved? I tried promise.resolve(), but it didn't help.

我使用提供程序的方式我以为我强迫应用程序使用相同的Links实例，而且我认为数据已经在那儿了.请问我做错了什么?

The way I used providers I thought I forced the app to use the same instance of Links and also I thought the data would be already present there. What am I doing wrong please?

推荐答案

在我的代码中，我所做的工作完全相同，唯一的区别是，我在映射之前将请求转换为Promise.

In my code I am doing exactly same and it's working only difference is that I am converting the request to Promise before mapping.

public load(): Promise<void> {
    let headers = new Headers({ 'Content-Type': 'application/json' });
    let url = this.urls.settings;

    return this.http.get(url, { headers }).toPromise().
        then(configs => {
            this.startupSettings = configs.json();
        }).catch(err => {
            log(err);
        });
}

......................

...............................

    {
        provide: APP_INITIALIZER,
        useFactory: (config: StartupConfigurationService) => () => config.load(),
        deps: [StartupConfigurationService],
        multi: true
    }

我不确定这是否有道理，但尝试可能会解决

I don't sure it will make sense but try may be it will solve

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