refactor(date-range): workaround for igxInput setting required on AfterViewInit

Author: jackofdiamond5

projects/igniteui-angular/src/lib/date-range-picker/date-range-picker.component.spec.ts

@@ -775,19 +775,20 @@ export class DateRangeTestComponent implements OnInit {
 @Component({
     selector: 'igx-date-range-two-inputs-test',
     template: `
-    <igx-date-range-picker [mode]="mode" [(ngModel)]="range">
+    <igx-date-range-picker [mode]="mode" [(ngModel)]="range" required>
             <igx-date-range-start>
-                <input igxInput igxDateTimeEditor type="text" required>
+                <input igxInput igxDateTimeEditor type="text">
             </igx-date-range-start>
             <igx-date-range-end>
-                <input igxInput igxDateTimeEditor type="text" required>
+                <input igxInput igxDateTimeEditor type="text">
             </igx-date-range-end>
         </igx-date-range-picker>
 `
 })
 export class DateRangeTwoInputsTestComponent extends DateRangeTestComponent {
     startDate = new Date(2020, 1, 1);
     endDate = new Date(2020, 1, 4);
+    range;
 }
 
 @Component({

projects/igniteui-angular/src/lib/date-range-picker/date-range-picker.component.ts

@@ -394,7 +394,7 @@ export class IgxDateRangePickerComponent extends DisplayDensityBase
     private get required(): boolean {
         if (this._ngControl && this._ngControl.control && this._ngControl.control.validator) {
             const error = this._ngControl.control.validator({} as AbstractControl);
-            return error && error.required;
+            return (error && error.required) ? true : false;
         }
 
         return false;
@@ -609,7 +609,6 @@ export class IgxDateRangePickerComponent extends DisplayDensityBase
         subsToClicked();
 
         this.setRequiredToInputs();
-        // detect changes?
 
         if (this._ngControl) {
             this._statusChanges$ = this._ngControl.statusChanges.subscribe(this.onStatusChanged.bind(this));
@@ -716,8 +715,11 @@ export class IgxDateRangePickerComponent extends DisplayDensityBase
     private setRequiredToInputs(): void {
         if (this.inputGroup && this.inputGroup.isRequired !== this.required) {
             this.inputGroup.isRequired = this.required;
-        } else if (this.hasProjectedInputs) {
-            this.projectedInputs.map(i => i.isRequired = this.required);
+        } else if (this.hasProjectedInputs && this._ngControl) {
+            // workaround for igxInput setting required
+            Promise.resolve().then(() => {
+                this.projectedInputs.map(i => i.isRequired = this.required);
+            });
         }
     }