Enhance a collection by incorporating methods to the result of an angular resource query

Question

Enhance a collection by incorporating methods to the result of an angular resource query

After executing a query, I am left with an array from the resource:

.factory('Books', function($resource){
    var Books = $resource('/authors/:authorId/books');
    return Books;
})

I was wondering if there is a way to incorporate prototype methods into the array received from this query? (Please note, not directly onto array.prototype).

For instance, I wish to include functions like hasBookWithTitle(title) within the collection.

javascript angularjs

Answer 1

Answer №1

While considering ricick's suggestion, it is important to note that implementing a method on the array may present some challenges. Essentially, creating a wrapper around $resource and its instances is necessary for achieving this functionality. The issue lies within a specific line of code in angular-resource.js:

var value = this instanceof Resource ? this : (action.isArray ? [] : new Resource(data));

This code snippet sets up the return value from $resource. During the execution of an ajax request, "value" is populated and returned. After the completion of the request, the value is assigned to "value", but by reference using the angular.copy() method. Each element of the array (such as query()) will be an instance of the resource being operated on.

To extend this functionality, one approach could involve modifying the following code (untested snippet which might require adjustments):

var myModule = angular.module('myModule', ['ngResource']);
myModule.factory('Book', function($resource) {
    var service = $resource('/authors/:authorId/books'),
        origQuery = service.prototype.$query;

    service.prototype.$query = function (a1, a2, a3) {
        var returnData = origQuery.call(this, a1, a2, a3);
        returnData.myCustomMethod = function () {
            // Implement custom method logic here...
        return returnData;
        }
    }

    return service;
});

Admittedly, further tweaking may be required to make it fully functional, but this serves as a basic outline of the concept.

Answer 2

While considering ricick's suggestion, it is important to note that implementing a method on the array may present some challenges. Essentially, creating a wrapper around $resource and its instances is necessary for achieving this functionality. The issue lies within a specific line of code in angular-resource.js:

var value = this instanceof Resource ? this : (action.isArray ? [] : new Resource(data));

This code snippet sets up the return value from $resource. During the execution of an ajax request, "value" is populated and returned. After the completion of the request, the value is assigned to "value", but by reference using the angular.copy() method. Each element of the array (such as query()) will be an instance of the resource being operated on.

To extend this functionality, one approach could involve modifying the following code (untested snippet which might require adjustments):

var myModule = angular.module('myModule', ['ngResource']);
myModule.factory('Book', function($resource) {
    var service = $resource('/authors/:authorId/books'),
        origQuery = service.prototype.$query;

    service.prototype.$query = function (a1, a2, a3) {
        var returnData = origQuery.call(this, a1, a2, a3);
        returnData.myCustomMethod = function () {
            // Implement custom method logic here...
        return returnData;
        }
    }

    return service;
});

Admittedly, further tweaking may be required to make it fully functional, but this serves as a basic outline of the concept.

Answer 3

Answer №2

One effective approach might be to develop a personalized service that extends the resource, incorporating additional utility methods into it rather than directly modifying the default resource service's return values.

var myModule = angular.module('myModule', []);
myModule.factory('Book', function() {
    var service = $resource('/authors/:authorId/books');
    service.hasBookWithTitle = function(books, title){
        //implement custom logic to return true or false
    }
    return service;
});

Subsequently,

books = Book.list(function(){
    //verify within the on complete method
    var hasBook = Book.hasBookWithTitle(books, 'someTitle');
})

Answer 4

One effective approach might be to develop a personalized service that extends the resource, incorporating additional utility methods into it rather than directly modifying the default resource service's return values.

var myModule = angular.module('myModule', []);
myModule.factory('Book', function() {
    var service = $resource('/authors/:authorId/books');
    service.hasBookWithTitle = function(books, title){
        //implement custom logic to return true or false
    }
    return service;
});

Subsequently,

books = Book.list(function(){
    //verify within the on complete method
    var hasBook = Book.hasBookWithTitle(books, 'someTitle');
})

Answer 5

Answer №3

Upon examining the code in angular-resource.js (specifically for the 1.0.x series), it doesn't seem possible to include a callback for default behavior (which, in my opinion, is the correct design).

If you only need the value in a single controller, you can provide a callback when calling query on the resource:

var books = Book.query(function(data) {
    data.hasBookWithTitle = function (title) { ... };
]);

Alternatively, you could create a service that enhances the Books resource by passing all calls to get/query/save/etc., and then adding your method to the array. For example, see this plunk: http://plnkr.co/edit/NJkPcsuraxesyhxlJ8lg

app.factory("Books",
  function ($resource) {
    var self = this;
    var resource = $resource("sample.json");

    return {
      get: function(id) { return resource.get(id); },
      // implement any other necessary functions like save, delete, etc.
      query: function() {
        return resource.query(
          function(data) { // success callback
            data.hasBookWithTitle = function(title) {
              for (var i = 0; i < data.length; i++) { 
                if (title === data[i].title) {
                  return true;
                }
              }
              return false;
            };
          },
          function(data, response) { /* optional error callback */}
        );
      }
    };
  }
);

Thirdly, and what I believe is a better approach depending on your needs, you can simply utilize the functional method by adding the hasBookWithTitle function to your controller or placing it in a utilities service if the logic needs to be shared.

Answer 6

Upon examining the code in angular-resource.js (specifically for the 1.0.x series), it doesn't seem possible to include a callback for default behavior (which, in my opinion, is the correct design).

If you only need the value in a single controller, you can provide a callback when calling query on the resource:

var books = Book.query(function(data) {
    data.hasBookWithTitle = function (title) { ... };
]);

Alternatively, you could create a service that enhances the Books resource by passing all calls to get/query/save/etc., and then adding your method to the array. For example, see this plunk: http://plnkr.co/edit/NJkPcsuraxesyhxlJ8lg

app.factory("Books",
  function ($resource) {
    var self = this;
    var resource = $resource("sample.json");

    return {
      get: function(id) { return resource.get(id); },
      // implement any other necessary functions like save, delete, etc.
      query: function() {
        return resource.query(
          function(data) { // success callback
            data.hasBookWithTitle = function(title) {
              for (var i = 0; i < data.length; i++) { 
                if (title === data[i].title) {
                  return true;
                }
              }
              return false;
            };
          },
          function(data, response) { /* optional error callback */}
        );
      }
    };
  }
);

Thirdly, and what I believe is a better approach depending on your needs, you can simply utilize the functional method by adding the hasBookWithTitle function to your controller or placing it in a utilities service if the logic needs to be shared.

Enhance a collection by incorporating methods to the result of an angular resource query

Answer №1

Answer №2

Answer №3

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