JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.5/angular.js"></script>
<div ng-app="myApp" ng-controller="demoCtrl">
    <input ng-model="entity[locationKey][cityKey]"/>
    <div>{{entity | json}}</div>
</div>

JavaScript

var app = angular.module('myApp', []);

app.controller('demoCtrl', function ($scope) {
    $scope.entity = {
        firstName: 'Jack',
        lastName: 'Bauer',
        city: 'LA',
        location: {
            city: 'New York'
        }
    };
    
    $scope.locationKey = 'location';
    $scope.cityKey = 'city';
});