I'm a huge fan of angular but it's got some tricky concepts with extremely nuanced differences between them and this is one of them.
I just want to create an class that I can use to create custom objects in my Angular controllers and factories. It surely shouldn't be that hard but I can't figure out how to do it. I want to have a custom, ResultSet class which I can instantiate to create instances of ResultSet. However for the life of me I can't figure out the correct syntax of factory v. service to use.
This is all I want:
ResultSet = function(dataSet){
this.filter = function(){
# filters and returns dataSet
# ...
}
}
and then I want to be able instantiate an instance of ResultSet inside a controller etc:
MyApp.controller('pageCtrl', ['ResultSet', (ResultSet) ->
# ...
rs = ResultSet.new(dataToFilter)
It seems more correct to use an Angular Service rather than a Factory since a service returns an instance of an object (which is exactly what I want). But I can't figure out how to do this...
How would I use a service to declare my custom ResultSet
class and then how would I instantiate an instance from it?
In AngularJS, a Controller is defined by a JavaScript constructor function that is used to augment the AngularJS Scope. Controllers can be attached to the DOM in different ways.
In AngularJS, $scope is the application object (the owner of application variables and functions). The controller creates two properties (variables) in the scope (firstName and lastName). The ng-model directives bind the input fields to the controller properties (firstName and lastName).
A provider is an object with a $get() method. The injector calls the $get method to create a new instance of a service. The Provider can have additional methods which would allow for configuration of the provider. AngularJS uses $provide to register new providers.
What is Factory in AngularJS? Factory is an angular function which is used to return the values. A value on demand is created by the factory, whenever a service or controller needs it. Once the value is created, it is reused for all services and controllers. We can use the factory to create a service.
Maybe you were looking for something like this:
.factory('User', function (Organisation) {
/**
* Constructor, with class name
*/
function User(firstName, lastName, role, organisation) {
// Public properties, assigned to the instance ('this')
this.firstName = firstName;
this.lastName = lastName;
this.role = role;
this.organisation = organisation;
}
/**
* Public method, assigned to prototype
*/
User.prototype.getFullName = function () {
return this.firstName + ' ' + this.lastName;
};
/**
* Private property
*/
var possibleRoles = ['admin', 'editor', 'guest'];
/**
* Private function
*/
function checkRole(role) {
return possibleRoles.indexOf(role) !== -1;
}
/**
* Static property
* Using copy to prevent modifications to private property
*/
User.possibleRoles = angular.copy(possibleRoles);
/**
* Static method, assigned to class
* Instance ('this') is not available in static context
*/
User.build = function (data) {
if (!checkRole(data.role)) {
return;
}
return new User(
data.first_name,
data.last_name,
data.role,
Organisation.build(data.organisation) // another model
);
};
/**
* Return the constructor function
*/
return User;
})
From this post by Gert Hengeveld.
myApp.factory('ResulSet', function() {
function ResultSetInstance(dataSet) {
this.filter = function(){
// ...
}
}
return {
createNew: function(dataSet) {
return new ResultSetInstance(dataSet);
}
};
});
and then
myApp.controller('pageCtrl', function(ResultSet) {
var someData = ...;
var rs = ResultSet.createNew(someData);
}
On experimenting with this further I found that you didn't even need to have the createNew
method.
myApp.factory('ResultSetClass', function() {
ResultSetClass = function(dataSet) {
this.filter = function(){
// ...
}
}
return ResultSetClass
});
works just fine and then you can call new ResultSetClass(args)
.
Coffeescript will return the last variable or method in your class instance so if you are using coffeescript (as a general rule), it's imperative to return this
at the end of the class definition
myApp.factory 'ResultSetClass', () ->
ResultSetClass = (dataset) ->
this.filter = () ->
# do some stuff
return this
return ResultSetClass
If you don't return this
explicitly then you'll find that when you call
myApp.factory 'ResultSetClass', () ->
ResultSetClass = (dataset) ->
this.filter = () ->
# do some stuff
then you'll simply be left with the last thing the coffeescript returns which is the filter
method.
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