Validate the access token before pass to the API request where we can avoid 401 failure

AngularClient/src/app/shared/services/auth-interceptor.service.ts

@@ -1,7 +1,7 @@
 import { AuthService } from './auth.service';
 import { Injectable } from '@angular/core';
 import { HttpInterceptor, HttpRequest, HttpHandler, HttpEvent, HttpHeaders } from '@angular/common/http';
-import { Observable, from } from 'rxjs';
+import { Observable, from, lastValueFrom } from 'rxjs';
 import { Constants } from '../constants';
 
 @Injectable({
@@ -13,17 +13,36 @@ export class AuthInterceptorService implements HttpInterceptor {
 
   intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
     if(req.url.startsWith(Constants.apiRoot)){
-      return from(
-        this._authService.getAccessToken()
-        .then(token => {
-          const headers = new HttpHeaders().set('Authorization', `Bearer ${token}`);
-          const authRequest = req.clone({ headers });
-          return next.handle(authRequest).toPromise();
-        })
-      );
+     return this.interceptRequestWithAccessToken(req, next);
     }
     else {
       return next.handle(req);
     }
   }
+
+  interceptRequestWithAccessToken(request: HttpRequest<any>, next: HttpHandler) {
+    return from(
+      this._authService.getAccessToken()
+        .then(accessToken => {
+
+          if (!accessToken) {
+            this._authService.signinSilent().then(user => {
+              return this.updateRequestHeader(request, next, user.access_token);
+            });
+          } else {
+            return this.updateRequestHeader(request, next, accessToken);
+          }
+        })
+    );
+  }
+
+  updateRequestHeader(request: HttpRequest<any>, next: HttpHandler, accessToken: string) {
+    const headerss = request.headers.set(
+      "Authorization",
+      `Bearer ${accessToken}`
+    );
+
+    const authReq = request.clone({ headers: headerss });
+    return lastValueFrom(next.handle(authReq));
+  }
 }

AngularClient/src/app/shared/services/auth.service.ts

@@ -32,6 +32,10 @@ export class AuthService {
     return this._userManager.signinRedirect();
   }
 
+  public signinSilent(): Promise<User> {
+    return this.userManager.signinSilent();
+  }
+
   public isAuthenticated = (): Promise<boolean> => {
     return this._userManager.getUser()
     .then(user => {