In this tutorial, we’ll explore the differences between service, provider, and factory and learn how to implement them in AngularJS.
AngularJS provides several ways to create and manage services, including services, providers, and factories. Each of these methods has its own unique characteristics and use cases.
1. AngularJS Services:
AngularJS services are instances of a function constructor or objects that are created using the new keyword. They are singletons, meaning that they are instantiated only once and can be injected into various parts of your application. Services are great for encapsulating reusable business logic or functionality that needs to be shared among different components.
To create a service in AngularJS, you use the module.service syntax. Internally, AngularJS utilizes the new keyword to instantiate the service by invoking the function provided to module.service.
Syntax:
module.service('serviceName', function);
Example:
angular.module('myApp').service('myService', function() {
this.doSomething = function() {
// Implementation
};
});
Here, myService is a service with a method doSomething that can be called from controllers, directives, or other services.
2. AngularJS Providers:
Providers are more configurable than services and offer additional configuration options. They can be injected into configuration blocks and are used during the configuration phase of an AngularJS application. Providers consist of a $get method that returns the service instance.
To define a provider in AngularJS, the module.provider syntax is used. Providers stand out as the most configurable and versatile means of creating services. Their ability to be configured during the module configuration phase makes them well-suited for handling module-wide configurations.
Syntax
module.provider('providerName', function);
Example
angular.module('myApp').provider('myProvider', function() {
var configValue = 'defaultValue';
this.setConfigValue = function(value) {
configValue = value;
};
this.$get = function() {
return {
getConfigValue: function() {
return configValue;
}
};
};
});
In this example, myProvider is a provider that allows configuration of a value using the setConfigValue method during the configuration phase and provides a getConfigValue method in its service instance.
3. AngularJS Factories:
Factories are simpler and more concise than providers. They are functions that return an object or a function representing the service. Factories are widely used because of their simplicity and ease of use.
Factories in AngularJS are created using the module.factory syntax. This involves defining a function that returns an object or a function. When declaring a factory, AngularJS invokes the function passed to module.factory and returns the value it produces.
Syntax
module.factory('factoryName', function);
Example
angular.module('myApp').factory('myFactory', function() {
var factory = {};
factory.doSomething = function() {
// Implementation
};
return factory;
});
In this example, myFactory is a factory that returns an object with a doSomething method.
When to Use Each:
- Services: Use services when you need a simple way to create a singleton object with methods and properties. They are straightforward and suitable for most use cases.
- Providers: Use providers when you need more configuration options or when you want to expose configurable settings during the configuration phase of your application.
- Factories: Use factories when you want a simple way to create services without the additional configuration overhead of providers. Factories are concise and often sufficient for common scenarios.
Conclusion:
Understanding the differences between AngularJS services, providers, and factories allows you to choose the right tool for the job. Experiment with each approach to gain hands-on experience and determine which one best suits your application’s requirements.