Fix Validation for input field

src/app/components/shared/room-join/room-join.component.html

@@ -8,7 +8,7 @@
                         placeholder="Session-Id" [formControl]="roomFormControl" [errorStateMatcher]="matcher"/>
       <mat-hint align="end">{{ roomId.value.length - (roomId.value.split(' ').length -1) }} / 8</mat-hint>
       <mat-error *ngIf="roomFormControl.hasError('required')">{{ 'home-page.please-enter' | translate}}</mat-error>
-      <mat-error *ngIf="roomFormControl.hasError('minlength')">{{ 'home-page.exactly-8' | translate}}</mat-error>
+      <mat-error *ngIf="roomFormControl.hasError('pattern')">{{ 'home-page.only-numbers' | translate}}</mat-error>
     </mat-form-field>
     <button mat-fab color="accent" type="submit">
       <mat-icon>input</mat-icon>

src/app/components/shared/room-join/room-join.component.ts

@@ -30,7 +30,7 @@ export class RoomJoinComponent implements OnInit {
   demoId = '95680586';
   user: User;
 
-  roomFormControl = new FormControl('', [Validators.required, Validators.minLength(9), Validators.maxLength(9)]);
+  roomFormControl = new FormControl('', [Validators.required, Validators.pattern('[0-9 ]*')]);
 
   matcher = new RegisterErrorStateMatcher();
 
@@ -46,7 +46,16 @@ export class RoomJoinComponent implements OnInit {
   }
 
   getRoom(id: string): void {
-    this.roomService.getRoomByShortId(id.replace(/\s/g, ""))
+    if (id.length -1 < 8) {
+      this.translateService.get('home-page.exactly-8').subscribe(message => {
+        this.notificationService.show(message);
+      });
+    } else if (this.roomFormControl.hasError('pattern')) {
+      this.translateService.get('home-page.only-numbers').subscribe(message => {
+        this.notificationService.show(message);
+      });
+    } else {
+      this.roomService.getRoomByShortId(id.replace(/\s/g, ""))
       .subscribe(room => {
         this.room = room;
         if (!room) {
@@ -65,6 +74,8 @@ export class RoomJoinComponent implements OnInit {
           }
         }
       });
+    }
+    
   }
 
   joinRoom(id: string): void {

src/assets/i18n/home/de.json

@@ -25,7 +25,8 @@
 		"create-session": "Session erstellen",
     "no-empty-name": "Bitte geben Sie einen Namen ein.",
     "created-1": "Session '",
-    "created-2": "' erfolgreich erstellt."
+		"created-2": "' erfolgreich erstellt.",
+		"only-numbers": "Eine Session-Id besteht aus Nummern."
   },
 	"login": {
 		"email": "E-Mail",

src/assets/i18n/home/en.json

@@ -25,7 +25,8 @@
 		"create-session": "Create session",
     "no-empty-name": "Please enter a name.",
     "created-1": "Session '",
-    "created-2": "' successfully created."
+		"created-2": "' successfully created.",
+		"only-numbers": "A session-id only contains numbers."
   },
 	"login": {
 		"email": "E-Mail",