Angular 5 http post method not called in nodejs

Question

I have a nodejs as Backend Service and angular 5 as front end, I want to call a POST method to NodeJS Server, send a Blob File to server.

But that post method is executed, and nothing shown on backend console log.

Here are some code piece:

server.js

const express = require('express');
const app = express();
const port = process.env.PORT || 3000;
const bodyParser = require('body-parser');
const cors = require('cors');
app.use(cors());
//create a cors middleware
app.use(function (req, res, next) {
  //set headers to allow cross origin request.
  res.header("Access-Control-Allow-Origin", "*");
  res.header('Access-Control-Allow-Methods', 'PUT, GET, POST, DELETE, OPTIONS');
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  next();
});
app.post('/decrypt', function (req, res) {
  console.log("decrypt called");
  return 'data back';
})

And in AngularJS: database.services.ts:

import { Injectable, Input } from '@angular/core';
import { Http, Response, ResponseContentType } from '@angular/http';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/do';
import { Observable } from 'rxjs/Observable';
import { saveAs, FileSaver } from 'file-saver/FileSaver';
import { HttpClientModule, HttpClient, HttpHeaders, HttpParams } from '@angular/common/http';

@Injectable()
export class DatabaseService {

  private API_GET_LIST_FILES = 'http://localhost:3000/files';

  private BASE_URL = 'http://localhost:3000/';

  private API_GET_FILE = 'http://localhost:3000/download?name=';

  constructor(private http: Http) { }

  getFile(key: string) {
    return this.http.get(this.API_GET_FILE + key, {
      responseType: ResponseContentType.Blob
    })
      .map(res => {
        return {
          filename: key.split('/').pop(),
          data: res.blob()
        };
      })
      .subscribe(res => {
        this.decryptFile(res.data);
        saveAs(res.data, res.filename);
      }, error => {
        console.log('download error:', JSON.stringify(error));
      }, () => {
        console.log('Completed file download.');
      })
  }

  decryptFile(data: any): Observable<any> {
    const httpOptions = {
      Headers: new HttpHeaders({
        'Content-Type': 'application/octet-stream',
        'data': data
      })
    };
    console.log(data, typeof data, this.BASE_URL + `decrypt`);
    return this.http.post(`http://localhost:3000/decrypt`, httpOptions);
  }
}

This getFile function will be called once I click the file download button on page, because in the browser console, it will print out the Blob(564534) {size: 564534, type: "application/octet-stream"} "object" "http://localhost:3000/decrypt"

I want the nodejs Server to take this post method and the Blob (GPG file) object as a parameter, and do something.

But looks like the backend server didn't print out anything.

Please advise how to modify this code, should I use POST or PUT? I want to pass a GPG file to nodeJS server and decrypt it.

Thanks,

Answer 1

decryptFile returns Observable , you must subscribe to it to execute the http call:

this.decryptFile(res.data).subscribe(decrypted => {???});

---

Edit: Could not resist, a few observations, feel free to ignore:

• Why do you get a file from server and then send it back there? Why don't you just decrypt the file during the first API call and return that?
• From security point of view... nevermind, I just hope there will be some authorization on the server as you are dealing with PGP files...
• You should preferably start using HttpClient from @angular/common/http instead of Http . Good news is you have that imported already.
• Depending on the size of the files you might want to consider using http upload instead of POST. Still, see the first point.