Angular 17 Custom Guard Not Working in Combination with Backend Axios Request? Let’s Debug!

Are you tired of banging your head against the wall, trying to figure out why your custom Angular 17 guard isn’t working in combination with a backend Axios request? You’re not alone! In this article, we’ll dive deep into the world of Angular guards and Axios requests, and provide you with a step-by-step guide to debug and fix this frustrating issue.

What is a Custom Angular Guard?

A custom Angular guard is a class that implements the `CanActivate` interface, which allows you to control access to specific routes in your Angular application. Guards are essential for implementing authentication and authorization in your app.

Here’s an example of a basic custom guard:

import { Injectable } from '@angular/core';
import { CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot } from '@angular/router';

@Injectable({
  providedIn: 'root'
})
export class CustomGuard implements CanActivate {
  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): boolean {
    // Your custom logic here
    return true;
  }
}

What is Axios?

Axios is a popular JavaScript library used for making HTTP requests in Node.js and browser environments. In Angular, we often use Axios to make requests to our backend API.

Here’s an example of making a GET request using Axios:

import axios from 'axios';

axios.get('https://api.example.com/data')
  .then(response => {
    console.log(response.data);
  })
  .catch(error => {
    console.error(error);
  });

The Problem: Custom Guard Not Working with Axios Request

So, what happens when you try to combine a custom Angular guard with a backend Axios request? You might expect the guard to block the route if the request fails or returns an error. But, what if the guard isn’t working as expected?

Here’s an example of what might be happening:

import { Injectable } from '@angular/core';
import { CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot } from '@angular/router';
import axios from 'axios';

@Injectable({
  providedIn: 'root'
})
export class CustomGuard implements CanActivate {
  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): boolean {
    axios.get('https://api.example.com/authenticate')
      .then(response => {
        if (response.data.success) {
          return true;
        } else {
          return false;
        }
      })
      .catch(error => {
        return false;
      });
  }
}

In this example, the custom guard makes an Axios GET request to the backend API to authenticate the user. If the request succeeds, the guard returns `true`, allowing the route to activate. If the request fails, the guard returns `false`, blocking the route.

But, what if the guard isn’t working as expected? What if the route is still being activated even when the Axios request fails?

Debugging the Issue

To debug this issue, let’s break down the problem into smaller parts:

1. Check the network request**: Open the browser’s DevTools and inspect the network request made by Axios. Verify that the request is being sent to the correct URL and that the request headers and body are correct.
2. Verify the Axios response**: Inspect the response received from the backend API. Check the response status code, headers, and body. Ensure that the response is what you expect.
3. Check the guard’s return value**: Add a debugger or console log statement in the guard’s `canActivate` method to verify that it’s returning the correct value (true or false) based on the Axios response.
4. Inspect the Angular router’s behavior**: Use the Angular Router’s debugging tools to inspect the router’s behavior. Verify that the router is correctly interpreting the guard’s return value.

axios.create({
  headers: {
    'Authorization': 'Bearer YOUR_TOKEN',
    'Content-Type': 'application/json'
  }
});

axios.create({
  timeout: 5000 // 5 seconds
});

axios.get('https://api.example.com/authenticate')
  .then(response => {
    if (response.status === 200 && response.data.success) {
      return true;
    } else {
      return false;
    }
  })
  .catch(error => {
    return false;
  });

@NgModule({
  imports: [RouterModule.forRoot([
    {
      path: 'protected-route',
      component: ProtectedComponent,
      canActivate: [CustomGuard]
    }
  ])],
  providers: [CustomGuard]
})
export class AppModule {}