fetch data from different localhost in Angular

问题:

in Angular, ng serve --port 4200 --host 0.0.0.0 creates an instance of http server. I've been told, that in order to fetch data from server side scripts in Angular, another localhost is needed.

In ngOnInit I fetch the data:

  ngOnInit(){
    this.http.get('http://localhost/echo.php').subscribe(data => {
      console.log(data);      
    });
  }

This fetch has a status code 200 in Network tab of Developer tools but I am getting a CORS error in the console:

Failed to load http://localhost/echo.php: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:4200' is therefore not allowed access.

It appears that differenr ports cause this. What should I do to prevent that? Browser itself has no issue by fetching this file, it is Angular that complains.

UPDATE: I've followed the suggestions and came up with a new error. this time it is: GET http://localhost:4200/backend/echo.php 504 (Gateway Timeout)

the "other" server is configured to listen to port 80 with DocumentRoot being backend ..

proxy.conf.json:

{
  "/backend/*": {
    "target": "http://localhost:80",
    "secure": false,
    "logLevel": "debug"
  }
}

.ts:

  ngOnInit(){
    this.http.get('http://localhost:4200/backend/echo.php').subscribe(data => {
      console.log(data);      
    });
  }

file structure:

回答1:

You can proxy your application on http://localhost by creating a file called proxy.conf.json in your angular project with the following content:

{
  "/api": {
    "target": "http://localhost",
    "secure": false
  }
}

and then starting ng serve with the additional parameter --proxy-config proxy.conf.json

ng serve --port 4200 --host 0.0.0.0 --proxy-config proxy.conf.json

You have to change your call then to include the port and /api prefix:

this.http.get('http://localhost:4200/api/echo.php').subscribe(data => {
...

You can find more details here

回答2:

If you have Tow loalhost application, first is Angular app and is running in http://localhost:4200 and another is API project and running in http://localhost:3000, In this situation if from your angular app make request to another, you get CORS error, for solving this problem you can use below instructions step by step:

1. Make a file and name it proxy.config.json inside main folder of Angular project like below image:

2. Then put codes inside created file like this (please notice to target part):

   {
       "/api/*": {
           "target": "http://localhost:3000",
           "secure": false,
           "logLevel": "debug"
       }
   }
   

3. Then Change package.josn file and insert code like below image"

4. And after all you must use npm start to running anglar project

Note: If you don't do it for angular project, you will occure with CORS problem.