AngularJs : how to use express {{}} in ng-if directive.?

Question

How to use the expression in ng-if.?

I have tried this

<span ng-if="formName.{{textboxCntl.name}}.$error.invalidValue && formName.{{textboxCntl.name}}.$dirty"
    id="{{textboxCntl.name}}-error"> Some error message
</span>

I'm using Angular 1.6.9

Answer 1

<span ng-if="formName[textboxCntl.name].$error.invalidValue && formName[textboxCntl.name].$dirty"

Just the way you do in JS