SVYX-926 TiNG Typehead issue when NULL has a displayValue

ngmodel needs to be able to also push te value back else a (change) even
will not be generated.

Author: jcompagner

projects/bootstrapcomponents/src/typeahead/typeahead.html

@@ -5,7 +5,7 @@
 		[svyStartEdit]="'dataProviderID'"
 		[hostComponent]="this"
 		[svyTabFix]="this"
-		[ngModel]="dataProvider"
+		[(ngModel)]="dataProvider"
 		(change)="pushUpdate()"
 		(selectItem)="valueChanged($event)"
 		[sabloTabseq]="tabSeq"

projects/bootstrapcomponents/src/typeahead/typeahead.ts

@@ -69,7 +69,13 @@ export class ServoyBootstrapTypeahead extends ServoyBootstrapBasefield<HTMLInput
         if (this.dataProviderID === null) return this.NULL_VALUE;
         return this.dataProviderID;
     }
-
+    
+    set dataProvider(value){
+        if (value === this.NULL_VALUE) this.dataProviderID = null;
+        else this.dataProviderID = value;
+    
+    }
+ 
     svyOnChanges(changes: SimpleChanges) {
         super.svyOnChanges(changes);
         if (changes.enabled || changes.findmode) {