NodeJS server can't retrive post data from Angular - node.js

Question

I have a backend server writen in NodeJS, which use express.
I have the latest Angular as frontend, I post a data (GPG file) to the nodeJS server, and I try to get that data in NodeJS code, and print it out in the server console, but all I get is an empty object.
All I want to do is to either pass the Blob data to node server, or to pass a plain text to node server, and read it from node code.
const express = require('express'),
app = express(),
port = process.env.PORT || 3000;
app.listen(port);
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();
});
const bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
extended: true
}));
app.post('/decrypt', (res, req) => {
// Here I try to access the data that I passed by POST method
console.log(res.body);
return 'data back';
})
This is my Angular Code:
import { Injectable, Input } from '#angular/core';
import { HttpClient, HttpResponse, HttpHeaders } from '#angular/common/http';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/do';
import { Observable } from 'rxjs/Observable';
import { saveAs } from 'file-saver/FileSaver';
#Injectable()
export class DatabaseService {
private API_GET_LIST_FILES = 'http://localhost:3000/files';
private API_GET_FILE = 'http://localhost:3000/download?name=';
private BASE_URL = 'http://localhost:3000/';
constructor(private http: HttpClient) { }
getFile(key: string) {
return this.http.get(this.API_GET_FILE + key, {
responseType: 'blob'
})
.map(res => {
return {
filename: key.split('/').pop(),
data: res
};
})
.subscribe(res => {
console.log('start download:', res);
// no matter what I pass here to the decrypt function, I can't get it in nodeJS server
this.decrypt(res.filename)
.subscribe(
next => console.log(next)
);
saveAs(res.data, res.filename);
}, error => {
console.log('download error:', JSON.stringify(error));
}, () => {
console.log('Completed file download.');
});
}
decrypt(res): Observable<any> {
const httpOptions = {
headers: new HttpHeaders({
'Content-Type': 'application/octet-stream'
})
};
return this.http.post(this.BASE_URL + 'decrypt', res, httpOptions);
}
}
If I pass the ***res*** to the decrypt function, I will get a lot info but looks weird to me.

Answer 1

Do what Anand suggested, set headers to application/json (or just skip httpOptions completely as that is default) and send {name: res}. Request body then should be just that.
For file upload you should use Express middleware like Multer or Multiparty. On Angular side for example ng2-file-upload.
Express method callback signature is (req, res, next) not (res, req), it is confusing when reading your code :(
And if you just return from callback, it will hang until http request times out (I think). You should do res.status(200).end() or res.json({done: true}) or anything similar.