如何将参数从angular 2服务传递给node js函数？ 意思

Question

I have a posts collection and each post has an id and userId .

I want to find all posts for a specific user (using userId property)..

here is my angular2 service:

    export class PostsService {

    private _url = '/api/posts';

    constructor(private _http: Http) { }

    getPosts(): Observable<Post[]> {
        return this._http.get(this._url).map(res => res.json());
    }
    getUserPosts(userId: number) {
        return this._http.get(this._url + '/' + userId).map(posts => posts.json());
    }
}

and my nodejs code :

router.get('/posts', function(req, res) {
    post.find({}).exec(function(err, posts) {
        if (err) {
            console.log("ERROR FETCHING POSTS!!");
        } else {
            res.json(posts);
        }
    });
});


router.get('/posts/:id', function(req, res) {
    post.findById(req.params.id).exec(function(err, posts) {
        if (err) {
            console.log("ERROR FETCHING POSTS!!" + err);
        } else {
            res.json(posts);
        }
    });
});

Answer 1

You need to send query params to the backend to be able to filter them in you nodejs controllers.In your Angular Service you'll have something like this:

export class PostsService {

    private _url = '/api/posts';

    constructor(private _http: Http) { }

    getPosts(): Observable<Post[]> {
        return this._http.get(this._url).map(res => res.json());
    }
 getUsersPost():Observable<Post[]>{
    let params - new HttpParams();
    params = params.append('user_id', userIdValue );
    return this._http.get(this._url, { params: params }). subscribe(....more code)
}
    getUserPosts(userId: number) {
        return this._http.get(this._url + '/' + userId).map(posts => posts.json());
    }
}

the final URL would be something like this: /api/posts?user_id=userIdValue .You need to import HttpParams from '@angular/common/http' I'm supposing you have Angular > 4.3, for more info about HttpParams refer to Angular Official Doc

Now, you just have to filter your post in your nodejs controller:

router.get('/posts', function(req, res) {
let query = {};
if(typeof req.query.user_id != 'undefined'){
    query['createdBy'] = req.query.user_id // supposing that 'createdBy' is where you store the user id's in post scheme 
}
    post.find(query).exec(function(err, posts) {
        if (err) {
            console.log("ERROR FETCHING POSTS!!");
        } else {
            res.json(posts);
        }
    });
});

If the user_id query param is not provided the post.find function will return all posts, if it is provided will return all the posts created by that user. Hope this help.

Answer 2

在跳入代码之前，请完成本教程。

https://angular-2-training-book.rangle.io/handout/http/