The “with” binding of KnockoutJS in AngularJS?

Question

I have just switched from KnockoutJS to AngularJS and I am not able to find the KnockoutJS\'s \"with\" data-bind in AngularJS.

Here is the piece of code in KnockoutJ

Answer 1

Create a custom directive that loops through the source object and creates corresponding properties on the directive's scope that are getter/setter references to the source object.

Check out this plunker.

directive module:

angular.module('koWith', [])
  .directive('koWith', function () {
    return {
      controller: function ($scope, $attrs) {
        var withObj = $scope.$parent[$attrs.ngWith];

        function getter(prop) {
          return this[prop];
        }
        function setter(val, prop) {
          this[prop] = val;
        }

        for (var prop in withObj) {
          if (withObj.hasOwnProperty(prop)) {
            Object.defineProperty($scope, prop, {
              enumerable: true,
              configurable: true,
              get: getter.bind(withObj, prop),
              set: setter.bind(withObj, prop)
            });
          }
        }
      },
      restrict: 'A',
      scope: true
    };
  });

app module:

angular.module('myApp', [])
  .controller('myController', function ($scope) {
    $scope.customer = {
      name: "Timmeh",
      address: {
        address1: "12 S Street",
        address2: "",
        city: "South Park",
        state: "CO",
        zipCode: "80440"
      }
    };
  });

html:

  
{{name}}
  

    {{address1}}

    {{address2}}

    {{city}}, {{state}} {{zipCode}}
  

Explanation

In KnockoutJS, bindings keep the bindingContext and data separated so creating the with binding is trivial since it only needs to create a new child bindingContext from the current one and use the with object as its data value.

In AngularJS, a directive's scope is basically the bindingContext and data object rolled into one. When a new scope is created, in order to get the with-like behavior, the properties of the with object have to be referenced onto the newly created scope object.