Boolean
Ensures the value of a field is a boolean. Also it will cast following strings to their boolean counter parts.
#Directive Code Snippet
<!DOCTYPE html>
<html lang="en">
...
<form (ngSubmit)="onSubmit(form)" #form="ngForm">
<input [boolean] type="text" name="<name>" [(ngModel)]="<name>" #<name>="ngModel">
</form>
...
</html>
#Chain Rule Code Snippet
<!DOCTYPE html>
<html lang="en">
...
<form (ngSubmit)="onSubmit(form)" #form="ngForm">
<input [Rule]="boolean" type="text" name="<name>" [(ngModel)]="<name>" #<name>="ngModel">
</form>
...
</html>