后期操作不適用於Angular 4

Question

我正在使用Angular 4學習Node.JS。我為簡單的GET / POST請求構建了一個示例Node API。 我的GET操作工作正常，我能夠在Angular中獲取數據。 我的OST操作根本沒有從Angular調用。 如果使用Postman，則可以成功調用POST，並且數據也將插入數據庫中。

這是我的Node POST示例代碼：

app.post('/groups', function (req, res, next){


res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "X-Requested-With, Content-Type");
res.header("Access-Control-Allow-Methods", "GET, POST","PUT");

console.log('Request received with body' + req.body);
//DEV AWS MySQL
var mysql = require('mysql');

var connection = mysql.createConnection({
                      host     : 'xxxxxxx',
                      user     : 'xxxxxxx',
                      password : 'xxxxxxx',
                      database : 'xxxxxxx',
                      port     : 3306
});
connection.connect();

connection.query('CALL storedprocedure(?, ?, ?, ?, ?, ?)', [req.body.group_avatar_image,req.body.name,req.body.display_name,req.body.unique_id,req.body.description,req.body.adzone], function (err, results, fields){

    if (err)
        res.send(results);

    //res.status(201).send("Groups created successfully");
    res.status(201).send(results[0]);
});

與Postman一起使用時效果很好，我得到201。

這是我的Angular 4代碼：

    import { Injectable } from '@angular/core';
import { Http, Response,RequestOptions, Request, RequestMethod, Headers} from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/do';
import { Group } from './group';

@Injectable()
export class GroupsService{

    private _GroupsUrl = 'http://localhost:5000/api/groups';
    constructor(private _http: Http){};

    getGroups(): Observable<Group[]> {
        let headers = new Headers({ 'Content-Type': 'application/json' });
        headers.append('Accept', 'application/json');
        headers.append('Access-Control-Allow-Methods', 'POST, GET, OPTIONS, DELETE, PUT');
        headers.append('Access-Control-Allow-Origin', '*');
        //headers.append('Access-Control-Allow-Headers', "X-Requested-With, Content-Type, Origin, Authorization, Accept, Client-Security-Token, Accept-Encoding");
        let options = new RequestOptions({ method: RequestMethod.Post, headers: headers,  url:this._GroupsUrl  });    

        //debugger;
        return this._http.get(this._GroupsUrl)
                .map((Response: Response) => <Group[]>Response.json()[0])
                //.do(data => console.log ('ALL: ' + JSON.stringify(data)))
                .catch(this.handleError);
    }

    CreateGroup(GroupM): Observable<string>{

        let headers = new Headers({ 'Content-Type': 'application/json' });
            headers.append('Access-Control-Allow-Methods', 'POST, GET, OPTIONS, DELETE, PUT, OPTIONS');
            headers.append('Access-Control-Allow-Origin', 'http://localhost:4200');
            headers.append('Access-Control-Allow-Headers', "X-Requested-With, Content-Type");
        //let options = new RequestOptions({ method: RequestMethod.Post, headers: headers, body:JSON.stringify(GroupM),  url:this._GroupsUrl  });    
        let options = new RequestOptions({ method: RequestMethod.Post});    

        console.log('Calling ' + this._GroupsUrl + ' with body as :' + JSON.stringify(GroupM) + ' and request options are : ' + JSON.stringify(options));

        var req = new Request(options.merge({
        url: this._GroupsUrl
        }));

        debugger;
        //return this._http.post(this._GroupsUrl,GroupM)
        return this._http.post(req.url,JSON.stringify(GroupM),options)
                     .map(res => res.json())
                     .do(data => console.log ('ALL: ' + JSON.stringify(data)))
                     .catch(this.handleError);
    }

    private handleError(error:Response) {
        console.error(error);
        return Observable.throw(error.json().error || 'Server Error');
    }
}

怎么了

Answer 1

最終能夠使用Promise解決它並解決了問題。 不確定可觀察的問題到底是什么。

>  CreateGroup(GroupObj:Group) : Promise<Group>{
        return this._http
                .post(this._GroupsUrl,JSON.stringify(GroupObj),{headers: this.headers})
                .toPromise()
                .then(res => res.json().data as Group)
                .catch(this.handleError);
    }

Answer 2

首先，幫自己一個忙，包裝Angular的Http服務，這樣您就不必為每個請求手動添加auth令牌和標頭。 這是一個可以建立的簡單實現：

首先，讓我們創建一個Cookies服務，該服務將作為不支持localStorage的后備：

@Injectable()

export class Cookies {

  public static getItem(sKey) {

    if (!sKey) {
      return null;
    }

    return decodeURIComponent(document.cookie.replace(new RegExp("(?:(?:^|.*;)\\s*" + encodeURIComponent(sKey).replace(/[\-\.\+\*]/g, "\\$&") + "\\s*\\=\\s*([^;]*).*$)|^.*$"), "$1")) || null;
  }

  public static setItem(sKey?, sValue?, vEnd?, sPath?, sDomain?, bSecure?) {

    if (!sKey || /^(?:expires|max\-age|path|domain|secure)$/i.test(sKey)) {
      return false;
    }

    let sExpires = '';

    if (vEnd) {

      switch (vEnd.constructor) {

        case Number:
          sExpires = vEnd === Infinity ? "; expires=Fri, 31 Dec 9999 23:59:59 GMT" : "; max-age=" + vEnd;
          break;

        case String:
          sExpires = "; expires=" + vEnd;
          break;

        case Date:
          sExpires = "; expires=" + vEnd.toUTCString();
          break;
      }
    }

    document.cookie = encodeURIComponent(sKey) + "=" + encodeURIComponent(sValue) + sExpires + (sDomain ? "; domain=" + sDomain : "") + (sPath ? "; path=" + sPath : "") + (bSecure ? "; secure" : "");

    return true;
  }

  public static removeItem(sKey, sPath?, sDomain?) {

    if (!this.hasItem(sKey)) {
      return false;
    }

    document.cookie = encodeURIComponent(sKey) + "=; expires=Thu, 01 Jan 1970 00:00:00 GMT" + (sDomain ? "; domain=" + sDomain : "") + (sPath ? "; path=" + sPath : "");

    return true;
  }

  public static hasItem(sKey) {

    if (!sKey) {
      return false;
    }

    return (new RegExp("(?:^|;\\s*)" + encodeURIComponent(sKey).replace(/[\-\.\+\*]/g, "\\$&") + "\\s*\\=")).test(document.cookie);
  }

  public static keys() {

    let aKeys = document.cookie.replace(/((?:^|\s*;)[^\=]+)(?=;|$)|^\s*|\s*(?:\=[^;]*)?(?:\1|$)/g, "").split(/\s*(?:\=[^;]*)?;\s*/);

    for (let nLen = aKeys.length, nIdx = 0; nIdx < nLen; nIdx++) {
      aKeys[nIdx] = decodeURIComponent(aKeys[nIdx]);
    }

    return aKeys;
  }
}

然后是一個存儲記錄器，該記錄器跟蹤添加到存儲中的內容（可用於在請求更改時為每個請求更新auth令牌）：

import {Cookies} from '@services/cookies.service';

@Injectable()

export class StorageLogger {

  private logger = new BehaviorSubject<any>(null);

  public logger$ = this.logger.asObservable();

  set(key: string, value: any): void {

    try {
      localStorage.setItem(key, JSON.stringify(value));
    }
    catch(err) {
      Cookies.setItem(key, JSON.stringify(value));
    }

    this.get(key);
  }

  get(key: string) {

    let item: any;

    try {
      item = JSON.parse(localStorage.getItem(key));
    }
    catch(err) {
      item = JSON.parse(Cookies.getItem(key));
    }

    this.logger.next({value: item, key: key});
  }

  remove(keys: string[]) {

    try {

      for (const key of keys) {
        localStorage.removeItem(key);
        this.logger.next({value: null, key: key});
      }
    }
    catch(err) {

      for (const key of keys) {
        Cookies.removeItem(key);
        this.logger.next({value: null, key: key});
      }
    }
  }
}

然后，您要包裝angular的Http ：

@Injectable()

/* Wrapper for Angular's Http class, let's us provide headers and other things on every request */
export class HttpClient implements OnDestroy {

  constructor(
    private http: Http,
    private storageLogger: StorageLogger
  ) {

    this.getToken();

    this.storageSubscription = this.storageLogger.logger$.subscribe(
      (action: any) => {

        if (action && action.key === tokenIdKey) {
          this.getToken();
        }
      }
    );
  }

  private storageSubscription: Subscription;
  private token: string;

  ngOnDestroy() {
    this.storageSubscription.unsubscribe();
  }

  getToken(): void {

    try {
      this.token = localStorage.getItem(tokenIdKey);
    }
    catch(error) {
      this.token = Cookies.getItem(tokenIdKey);
    }
  }

  convertJSONtoParams(json: any): URLSearchParams {

    const params: URLSearchParams = new URLSearchParams();

    for (const key in json) {

      if (json.hasOwnProperty(key) && json[key]) {

        if (json[key].constructor === Array && !json[key].length) {
          continue;
        }
        else {
          params.set(key, json[key]);
        }
      }
    }

    return params;
  }

  getRequestOptions(params?: any): RequestOptions {

    const headers = new Headers();

    // headers.append('Content-Type', 'application/x-www-form-urlencoded');
    headers.append('Content-Type', 'application/json');

    this.createAuthorizationHeader(headers);

    return new RequestOptions({
      headers: headers,
      search: params ? this.convertJSONtoParams(params) : null
    });
  }

  createAuthorizationHeader(headers: Headers): void {
    headers.append('Authorization', this.token);
  }

  checkResponseStatus(err: any) {

    if (err.status === 401) {

      // If we want we can redirect to login here or something else
    }

    return Observable.of(err);
  }

  get(url: string, params?: any): Observable<Response> {

    const options: RequestOptions = this.getRequestOptions(params);

    return this.http.get(host + url, options).catch((err: Response) => this.checkResponseStatus(err));
  }

  post(url: string, data: any, params?: any): Observable<Response> {

    const options: RequestOptions = this.getRequestOptions(params);

    return this.http.post(host + url, data, options).catch((err: Response) => this.checkResponseStatus(err));
  }

  put(url: string, data: any, params?: any): Observable<Response> {

    const options: RequestOptions = this.getRequestOptions(params);

    return this.http.put(host + url, data, options).catch((err: Response) => this.checkResponseStatus(err));
  }

  delete(url: string, params?: any): Observable<Response> {

    const options: RequestOptions = this.getRequestOptions(params);

    return this.http.delete(host + url, options).catch((err: Response) => this.checkResponseStatus(err));
  }

  patch(url: string, data: any, params?: any): Observable<Response> {

    const options: RequestOptions = this.getRequestOptions(params);

    return this.http.patch(host + url, data, options).catch((err: Response) => this.checkResponseStatus(err));
  }

  head(url: string, params?: any): Observable<Response> {

    const options: RequestOptions = this.getRequestOptions(params);

    return this.http.head(host + url, options).catch((err) => this.checkResponseStatus(err));
  }

  options(url: string, params?: any): Observable<Response> {

    const options: RequestOptions = this.getRequestOptions(params);

    return this.http.options(host + url, options).catch((err: Response) => this.checkResponseStatus(err));
  }
}

最后，您還應該添加一個將要調用的通用api服務，而不是為應用程序的每個部分創建一個新服務。 這將節省大量代碼和精力。 這里是：

import {IResponse} from '@interfaces/http/response.interface';
import {HttpClient} from '@services/http/http-client.service';

@Injectable()

export class AppApi {

  constructor(private http: HttpClient) {}

  get(url: string, params?: any): Observable<IResponse> {

    return this.http.get(url, params)
      .map((res: Response) => res.json() as IResponse)
      .catch((error: any) => {
        return Observable.throw(error.json().error || 'Server error');
      }
    );
  }

  post(url: string, data: any, params?: any) {

    return this.http.post(url, data, params)
      .map((res: Response) => res.json() as IResponse)
      .catch((error: any) => {
        return Observable.throw(error.json().error || 'Server error');
      }
    );
  }

  put(url: string, data: any, params?: any) {

    return this.http.put(url, data, params)
      .map((res: Response) => res.json() as IResponse)
      .catch((error: any) => {
        return Observable.throw(error.json().error || 'Server error');
      }
    );
  }

  delete(url: string, params?: any): Observable<IResponse> {

    return this.http.delete(url, params)
      .map((res: Response) => res.json() as IResponse)
      .catch((error: any) => {
        return Observable.throw(error.json().error || 'Server error');
      }
    );
  }
}

您會注意到，我還創建了一個接口，用於輸入來自后端的響應，通常是這樣的：

{error: any; data: any; results: number; total: number;}

現在我們已經解決了這些問題，讓我們解決您的原始問題。 關於您的請求為何未運行的最可能的原因是，您沒有訂閱可觀察的http 。 可觀察對象是懶惰的，因此，如果您不通過.subscribe或@ngrx/effects對其進行訂閱，則它不會執行任何操作。

因此，假設您正在像這樣調用CreateGroup ：

this.groupsService.CreateGroup(data);

除非您訂閱，否則它不會做任何事情：

this.groupsService.CreateGroup(data).subscribe(() => {

  // Here you can react to the post, close a modal, redirect or whatever you want.
});

我還建議向您的api調用添加.first() ，因為這樣做可以防止您在組件被破壞時手動取消訂閱可觀察對象。

因此，要使用上述實現，您只需執行以下操作：

constructor(private appApi: AppApi) {}

...

this.appApi.post('/groups').first().subscribe(() => {

  // Do something
});

我希望這是有幫助的。

Answer 3

不要在HTTP POST中對POST數據進行字符串化處理。 只需傳遞對象即可。