How to retrieve response headers and set request headers using the strategy described in the tutorial.

[javier hector]

Hi, All , I'm new to Angular and I want to know how to retrieve response headers and based on these values set request headers.

A use case for this should be set Conditional GET requests or Conditional PUT requests in a REST service.

For example

var MyApp = angular.module ('MyApp',['ngResource']);

MyApp.config(function($routeProvider, $locationProvider,$httpProvider) {

  $routeProvider

    .when('/', {controller: ListCtrl, templateUrl: '/partials/list.html'})

.when('/edit/:id', {controller: EditCtrl, templateUrl: '/partials/details.html'})

.when('/new', {controller: CreateCtrl, templateUrl: '/partials/details.html'})

    .otherwise({redirectTo: '/'});

   $locationProvider.html5Mode(true);

});

MyApp.factory('MyAppService', function($resource) {

  return $resource('/example/:id', {id: '@id'}, {update: {method: 'PUT'}});

  });

  

 

function EditCtrl ($scope, $location, $routeParams,MyAppService) {

 $scope.get = MyAppService.get({id: $routeParams.id}, function(data,headers) {

$scope.example = data.content;

$scope.ifmatch = headers().etag;

 });

 

  $scope.action = 'Update';

  $scope.save = function() {

    MyAppService.update({id: $routeParams.id},,$scope.example, function() {

      $location.path('/');

    })

  }

};

So suppose I want in the  the EditCtrl  set the if-match request header using the etag value sent from the server, if any.

I tried to do  send the {headers :{'if-match' : $scope.ifmatch}} as part of update call but it does not work.

  MyAppService.update({id: $routeParams.id}, {headers :{'if-match' : $scope.ifmatch}} ,$scope.example, function() {

What do you suggest to do in this scenario?

Thanks

/Javier

 

[Eduardo Martins Barbosa]

For this specific case, supposing your API returns a key etag along with the object you could define your service like this:

return $resource('/example/:id', {id: '@id'}, {
  update:

 {
    method: 'PUT',
    headers: {
      'If-Match': function(config) {
        return config.data.etag;
      }
    }
  }
});

This works for PUT and PATCH methods. If you also need it to work for DELETE, checkout this fork: https://github.com/eduardomb/ng-resource-etag