To create IntelliJ IDEA project files with Gradle we first need to apply the idea plugin. We can then further customise the created files. In this blog post we will add a Spring facet to the generated module file. By adding the Spring facet IntelliJ IDEA can automatically search for Spring configuration files. We can then use the Spring view to see which beans are configured in our project.

In the following example build file we use the withXml hook. This method is invoked just before the XML file is generated. We get an argument of typeXmlProvider. From the XmlProvider we can access the XML as org.w3c.dom.Element, StringBuilder or groovy.util.Node. We useNode to alter the XML. We check if a FacetManager component is available. We need this to add a facet of type Spring.

// File: build.gradle
apply plugin: 'groovy'
apply plugin: 'idea'

idea {
    module {
        iml {
            withXml { 
                // Get root of module as groovy.util.Node.
                def moduleRoot = it.asNode()

                // Find if component with name 'FacetManager'
                // is already set.
                def facetManager = moduleRoot.component.find { component -> component.'@name' == 'FacetManager'}
                if (!facetManager) {
                    // Create new component with name 'FacetManager'
                    facetManager = moduleRoot.appendNode('component', [name: 'FacetManager'])
                }

                // Find Spring facet it might already be there.
                def springFacet = facetManager.facet.find { facet -> facet.'@type' == 'Spring' && facet.'@name' == 'Spring' }
                if (!springFacet) {
                    // If not set create new facet node with name 'Spring'
                    // and type 'Spring' and apply a default configuration.
                    springFacet = facetManager.appendNode('facet', [type: 'Spring', name: 'Spring'])
                    springFacet.appendNode('configuration')
                }
            }
        }
    }
}

Written with Gradle 2.12 and IntelliJ IDEA 15.