add special method here too

ui/hv2-ui/src/app/ext-data-object-service.ts

@@ -0,0 +1,31 @@
+
+import { Injectable } from '@angular/core';
+import { HttpClient } from '@angular/common/http';
+
+import { MessageService } from './message.service';
+import { serviceBaseUrl } from './config';
+
+
+import { Account } from './data-objects';
+import { Tenant } from './data-objects';
+import { Premise } from './data-objects';
+import { Flat } from './data-objects';
+import { OverheadAdvance } from './data-objects';
+import { OverheadAdvanceFlatMapping } from './data-objects';
+import { Parking } from './data-objects';
+import { CommercialPremise } from './data-objects';
+import { Tenancy } from './data-objects';
+import { Fee } from './data-objects';
+import { TenancyFeeMapping } from './data-objects';
+import { AccountEntry } from './data-objects';
+
+
+@Injectable({ providedIn: 'root' })
+export class ExtOverheadAdvanceService {
+  constructor(private messageService: MessageService, private http: HttpClient) { }
+  
+  async getOverheadAdvancesByFlat(flatId: number): Promise<OverheadAdvance[]> {
+    this.messageService.add(`OverheadAdvanceService: get data by flat ${flatId}`);
+    return this.http.get<OverheadAdvance[]>(`${serviceBaseUrl}/v1/overhead_advances/flat/${flatId}`).toPromise()
+  }
+}