Creating custom traits

This tutorial takes you through the process of creating a custom trait. 

A trait is an attribute or property of a visitor or visit, such as age or gender, that you can use to personalize content. 

We create a trait that detects the visitor's operating system. Depending on the detected user agent, we serve the visitor a page with a personalized component. We create two component variants named "WINDOWS" and "OS-X" for a Text and image component.

The trait extracts the operating system from the User-Agent in the HTTP header:

• Windows users are served a component with text that refers to the Windows system and a download link at ftp://mgnl.travel/maps-offline/windows.zip.
• OS-X users are served a component with text that refers to the OS-X system and a download link at ftp://mgnl.travel/maps-offline/osx.zip.
• If neither system is detected, Magnolia serves the "ORIGINAL" version of the component, containing generic text and a download link at ftp://mgnl.travel/maps-offline/other-systems.zip.

Create a module

A trait is deployed with a Magnolia module. Create a module first. Choose from these options depending on your skill level:

Option 1: Clone the project in Git

This option gives you a ready-made project that you can customize to your needs.

Choose this option if you know how to work with a Magnolia project and Git, and want to examine the code locally in your IDE. 

1. Clone the documentation-trait-tutorial repository.

   git clone http://git.magnolia-cms.com/git/documentation/documentation-trait-tutorial.git

   After having cloned the repo, you can check out the tagged version for the tag named documentation-trait-tutorial-1.3:

   git checkout documentation-trait-tutorial-1.3

2. Import the project into your IDE. Here's what the project looks like in IntelliJ IDEA:

   

3. Build the project into a JAR and deploy it to your Magnolia instance. Or run the project in your IDE. To run it in an IDE, add the module as a dependency to your Magnolia bundle POM file (see Option 2).

Option 2: Add the project as a dependency to your bundle

Choose this option if you run Magnolia in your IDE, but don't plan to work on the code.

Add the project as a dependency in the POM files of your Magnolia bundle.

For Enterprise Edition bundles:

1. In the dependencyManagement section of the EE-bundle parent POM file, add a dependency element with a version number:
    

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2. In the dependencies section of the enterprise-webapp POM file, add a dependency element without a version number:
   

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    If you use IMB WebSphere or Oracle WebLogic, add the dependency element in the appropriate POM file of your webapp of choice.

If you are using a custom bundle, add the dependency element with a version number in the POM file of your customized bundle.

Option 3: Download the module JAR

Choose this option if you are new to Magnolia and don't have a development environment (IDE). You can use the trait but won't be able to look at the code.

1. Install the Magnolia Tomcat bundle.
2. Download

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    from Nexus.
   
3. Copy the JAR into <CATALINA_HOME>/webapps/<contextPath>/WEB-INF/lib folder. Typically this is <CATALINA_HOME>/webapps/magnoliaAuthor/WEB-INF/lib.
4. Restart your Magnolia instance and run the Web update . This will install the documentation-trait-tutorial module.

Registering a trait

Any module can register a trait. Magnolia observes the  traits folder in your module configuration and adds new traits to a trait registry. Registered traits are then displayed to editors in the user interface. 

Here's the userAgent trait.

Properties:

Rule field

A rule field defines values for the trait when you choose an audience. For example, you need two rule fields to define a date range: one for start date and another for end date. Magnolia uses the input entered into the rule field(s) to construct a voter. The voter then decides whether the visitor or visit matches the rule or not. When the rule is met, personalized content is delivered.

The rule field is displayed to users in the Choose audience dialog:

Choose a field definition class that lets the user specify the permitted values. In some cases, a simple text field is enough (country). In others, for example where you need the user to select a value (new visitor, registered visitor, logged-in visitor), a select field is appropriate. For more complex fields, use a composite field. See List of fields for more.

userAgent rule field:

Properties:

Value field

A value field is for previewing variants. The field is displayed to users in the Preview app when viewing the page as a visitor:

When you enter a value that matches the rule, for example "Macintosh" in the image above, the voter tests the value against the rule and Magnolia displays the content variant associated with the value.

userAgent value field:

Properties:

Registering a trait detector filter

Once you have registered the trait, provide a TraitDetectorFilter and register it in the filter chain to make sure the appropriate variant is served.

UserAgentDetectorFilter registration in the filter chain.

Properties:

Position of the filter in the chain

Make sure the filter is in the right position in the chain. Filters are executed in the order they are registered in the chain, from top to bottom. You want to position the filter right after the contentType filter.

When installing a module, you can define the position with ModuleVersionHandler#getExtraInstallTasks.

public class PersonalizationExamplesModuleVersionHandler extends DefaultModuleVersionHandler {
    @Override
    protected List<Task> getExtraInstallTasks(InstallContext installContext) {
        List<Task> tasks = new ArrayList<Task>();
        tasks.add(new FilterOrderingTask("userAgent", new String[]{"contentType"}));
        return tasks;
    }
}

In the example above the configuration tree is simplified. Other filters may also want to be right after contentType. In a production environment it may look like this: 

Creating component variants

Now you can create component variants and choose an audience using the new trait.

The documentation-trait-tutorial module installs an example page named maps-download that contains two custom variants of the Text and image component:

Windows variant

OS-X variant

Original

 It is not possible to specify an audience for the original. The original acts as fallback (default) content when no variants match the visitor.

Testing the result

You can test the personalized variants using a browser plugin or on different computers running Windows and OS-X. User agent switcher add-ons that allow you to spoof and mimic various user agents are available for Firefox, Chrome/Chromium, and Opera.

You should now be able to see different renderings of the page containing the personalized variants of the Text and image component depending on the user agent. 

Windows user agent

OS-X user agent

Other user agents