Strict done!!

overlord/src/app/purchases/purchases.component.ts

@@ -17,10 +17,10 @@ import { PurchasesItem } from './purchases-item';
 export class PurchasesComponent implements OnInit {
   @ViewChild(MatPaginator, { static: true }) paginator?: MatPaginator;
   @ViewChild(MatSort, { static: true }) sort?: MatSort;
-  dataSource: PurchasesDataSource;
+  info: Purchases = new Purchases();
+  dataSource: PurchasesDataSource = new PurchasesDataSource(this.info.body);
   form: FormGroup;
-  info: Purchases;
-  selectedRowId: string;
+  selectedRowId = '';
   /** Columns displayed in the table. Columns IDs can be added, removed, or reordered. */
   displayedColumns = ['product', 'quantity', 'rate', 'amount'];
 
@@ -40,7 +40,7 @@ export class PurchasesComponent implements OnInit {
         startDate: moment(this.info.startDate, 'DD-MMM-YYYY').toDate(),
         finishDate: moment(this.info.finishDate, 'DD-MMM-YYYY').toDate(),
       });
-      this.dataSource = new PurchasesDataSource(this.paginator, this.sort, this.info.body);
+      this.dataSource = new PurchasesDataSource(this.info.body, this.paginator, this.sort);
     });
   }