Next to creating controllers and directives, AngularJS also supports “singleton” services.
Services, like on the server-side, offer a great way for separating logic from your controllers.

In AngularJS anything that’s either a primitive type, function or object can be a service.

Although the concept of service is quite straight forward, the declaration of them in AngularJS isn’t:

There are 4 different ways to declare a service.
- Registering a existing value as a service
- Registering a factory function to create the singleton service instance
- Registering a constructor function to create the singleton service instance
- Registering a service factory which can be configured
Only 1 of them is extensively documented

The other 3 are only barely documentedThis post describes each option and when to use it in more detail.

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We can configure Spring beans using several methods in Grails. We can for example add them to grails-app/conf/spring/resources.xml using Spring’s XML syntax. But we can also use a more Groovy way with grails-app/conf/spring/resources.groovy. We can use a DSL to define or configure Spring beans that we want to use in our Grails application. Grails uses BeanBuilder to parse the DSL and populate the Spring application context.

To define a bean we use the following syntax beanName(BeanClass). If we want to set a property value for the bean we use a closure and in the closure we set the property values. Let’s first create a simple class we want to configure in the Spring application context:

// File: src/groovy/com/mrhaki/spring/Person.groovy
package com.mrhaki.spring

import groovy.transform.ToString

@ToString
class Person {
    String name
    Date birthDate
}

// File: src/groovy/com/mrhaki/spring/Person.groovy

package com.mrhaki.spring

import groovy.transform.ToString

@ToString

class Person {

String name

Date birthDate

}

Next we configure the bean in resources.groovy:

// File: grails-app/conf/spring/resources.groovy
import com.mrhaki.spring.Person

beans = {

    mrhaki(Person) {
        name = 'mrhaki'
        birthDate = Date.parse('yyyy-MM-dd', '1973-7-9')
    }

}

// File: grails-app/conf/spring/resources.groovy

import com.mrhaki.spring.Person

beans = {

mrhaki(Person) {

name = 'mrhaki'

birthDate = Date.parse('yyyy-MM-dd', '1973-7-9')

}

There is also an alternative syntax using Groovy’s support for named method arguments. In Groovy named arguments are all grouped into a Map object and passed as the first argument. The BeanBuilder DSL supports this feature. When we define a bean we can use named arguments for the property names and values, use the BeanClass argument and automatically this will be converted to Map and BeanClass type arguments.

// File: grails-app/conf/spring/resources.groovy
import com.mrhaki.spring.Person

beans = {

    // Using named arguments to set property values. The named arguments
    // can be grouped together, but don't have to. Groovy will automatically
    // group them together into a Map and makes it the first argument of
    // the 'mrhaki() bean definition method'.
    mrhaki(name: 'mrhaki', Person, birthDate: Date.parse('yyyy-MM-dd', '1973-7-9'))

}

// File: grails-app/conf/spring/resources.groovy

import com.mrhaki.spring.Person

beans = {

// Using named arguments to set property values. The named arguments

// can be grouped together, but don't have to. Groovy will automatically

// group them together into a Map and makes it the first argument of

// the 'mrhaki() bean definition method'.

mrhaki(name: 'mrhaki', Person, birthDate: Date.parse('yyyy-MM-dd', '1973-7-9'))

}

Written with Grails 2.2.1

Original article

Monthly Archives: March 2013

Quickly experiment with AngularJS (and Jasmine) using these Plunks

How to create (singleton) AngularJS services in 4 different ways

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Grails Goodness: Set Property Values of Spring Beans in resources.groovy