Strict done!!

overlord/src/app/product/product-detail/product-detail.component.ts

@@ -17,8 +17,8 @@ import { ProductService } from '../product.service';
 export class ProductDetailComponent implements OnInit, AfterViewInit {
   @ViewChild('nameElement', { static: true }) nameElement?: ElementRef;
   form: FormGroup;
-  productGroups: ProductGroup[];
-  item: Product;
+  productGroups: ProductGroup[] = [];
+  item: Product = new Product();
 
   constructor(
     private route: ActivatedRoute,
@@ -73,7 +73,7 @@ export class ProductDetailComponent implements OnInit, AfterViewInit {
 
   ngAfterViewInit() {
     setTimeout(() => {
-      this.nameElement.nativeElement.focus();
+      if (this.nameElement) this.nameElement.nativeElement.focus();
     }, 0);
   }
 
@@ -90,7 +90,7 @@ export class ProductDetailComponent implements OnInit, AfterViewInit {
   }
 
   delete() {
-    this.ser.delete(this.item.id).subscribe(
+    this.ser.delete(this.item.id as string).subscribe(
       () => {
         this.toaster.show('Success', '');
         this.router.navigateByUrl('/products');

overlord/src/app/product/product-list/product-list-datasource.ts

@@ -12,11 +12,11 @@ function compare(a: string | number, b: string | number, isAsc: boolean) {
   return (a < b ? -1 : 1) * (isAsc ? 1 : -1);
 }
 export class ProductListDataSource extends DataSource<Product> {
-  private filterValue: string = "";
+  private filterValue = '';
 
   constructor(
     public data: Product[],
-    private filter: Observable<string>,
+    private readonly filter: Observable<string>,
     private paginator?: MatPaginator,
     private sort?: MatSort,
   ) {
@@ -83,8 +83,6 @@ export class ProductListDataSource extends DataSource<Product> {
           return compare(a.name, b.name, isAsc);
         case 'productGroup':
           return compare(a.productGroup.name, b.productGroup.name, isAsc);
-        case 'id':
-          return compare(+a.id, +b.id, isAsc);
         default:
           return 0;
       }

overlord/src/app/product/product-list/product-list.component.ts

@@ -1,5 +1,5 @@
 import { AfterViewInit, Component, ElementRef, OnInit, ViewChild } from '@angular/core';
-import { FormBuilder, FormGroup } from '@angular/forms';
+import { FormBuilder, FormControl, FormGroup } from '@angular/forms';
 import { MatPaginator } from '@angular/material/paginator';
 import { MatSort } from '@angular/material/sort';
 import { ActivatedRoute } from '@angular/router';
@@ -20,22 +20,27 @@ export class ProductListComponent implements OnInit, AfterViewInit {
   @ViewChild('filterElement', { static: true }) filterElement?: ElementRef;
   @ViewChild(MatPaginator, { static: true }) paginator?: MatPaginator;
   @ViewChild(MatSort, { static: true }) sort?: MatSort;
+  list: Product[] = [];
+  filter: Observable<string>;
   dataSource: ProductListDataSource;
-  filter: Observable<any>;
   form: FormGroup;
-  list: Product[];
   /** Columns displayed in the table. Columns IDs can be added, removed, or reordered. */
-  displayedColumns: string[];
+  displayedColumns: string[] = [];
 
   // eslint-disable-next-line no-underscore-dangle
-  private _showExtended: boolean;
+  private _showExtended = false;
 
   constructor(private route: ActivatedRoute, private fb: FormBuilder, private toCsv: ToCsvService) {
     this.showExtended = false;
     this.form = this.fb.group({
       filter: '',
     });
-    this.filter = this.listenToFilterChange();
+    this.filter = (this.form.get('filter') as FormControl).valueChanges.pipe(
+      startWith(''),
+      debounceTime(150),
+      distinctUntilChanged(),
+    );
+    this.dataSource = new ProductListDataSource(this.list, this.filter);
   }
 
   get showExtended(): boolean {
@@ -53,24 +58,18 @@ export class ProductListComponent implements OnInit, AfterViewInit {
     }
   }
 
-  listenToFilterChange() {
-    return this.form
-      .get('filter')
-      .valueChanges.pipe(startWith(''), debounceTime(150), distinctUntilChanged());
-  }
-
   ngOnInit() {
     this.route.data.subscribe((value) => {
       const data = value as { list: Product[] };
 
       this.list = data.list;
     });
-    this.dataSource = new ProductListDataSource(this.paginator, this.sort, this.filter, this.list);
+    this.dataSource = new ProductListDataSource(this.list, this.filter, this.paginator, this.sort);
   }
 
   ngAfterViewInit() {
     setTimeout(() => {
-      this.filterElement.nativeElement.focus();
+      if (this.filterElement) this.filterElement.nativeElement.focus();
     }, 0);
   }
 

overlord/src/app/product/product.service.ts

@@ -17,7 +17,7 @@ const serviceName = 'ProductService';
 export class ProductService {
   constructor(private http: HttpClient, private log: ErrorLoggerService) {}
 
-  get(id: string): Observable<Product> {
+  get(id: string | null): Observable<Product> {
     const getUrl: string = id === null ? `${url}` : `${url}/${id}`;
     return <Observable<Product>>(
       this.http