fixed errors with ngModel

src/app/app.module.ts

@@ -4,6 +4,7 @@ import { BrowserModule } from '@angular/platform-browser';
 import { NgModule } from '@angular/core';
 import { LocationStrategy, HashLocationStrategy } from '@angular/common';
 import { HttpClientModule } from '@angular/common/http';
+import { FormsModule, ReactiveFormsModule } from '@angular/forms';
 
 import { AppComponent } from './app.component';
 import { BsDropdownModule } from 'ngx-bootstrap/dropdown';
@@ -50,6 +51,8 @@ import { MoreStuffComponent } from './dashboard/more-graphs-and-tables.component
   imports: [
     BrowserModule,
     HttpClientModule,
+    FormsModule,
+    ReactiveFormsModule,
     NgxPaginationModule,
     BsDropdownModule.forRoot(),
     TabsModule.forRoot(),

src/app/dashboard/more-graphs-and-tables.component.html

@@ -6,8 +6,8 @@
           <h4 class="card-title mb-0">Spend amount and number of purchases by supplier name</h4>
         </div>
         <div class="col-sm-5 hidden-sm-down">
-          <input type="date" id="bubbleChartBegin" name="bubbleChartBegin" [(ngModel)]="bubbleChartBegin" (ngModelChange)="bubbleChartUpdate()">
-          <input type="date" id="bubbleChartEnd" name="bubbleChartEnd" [(ngModel)]="bubbleChartEnd" (ngModelChange)="bubbleChartUpdate()">
+          <input type="date" [(ngModel)]="bubbleChartBegin" (ngModelChange)="bubbleChartUpdate()">
+          <input type="date" [(ngModel)]="bubbleChartEnd" (ngModelChange)="bubbleChartUpdate()">
         </div>
       </div>
       <div>

src/app/dashboard/more-graphs-and-tables.component.ts

@@ -13,6 +13,7 @@ export class MoreStuffComponent implements OnInit {
   @Input() public categories: any;
   bubbleChartBegin: any;
   bubbleChartEnd: any;
+  
   constructor(
     private api: ApiService,
     private currencyPipe: CurrencyPipe,