This is an advanced topic.
It is not necessary to use a model in Magnolia templating, but it is useful. If you are starting out with Magnolia use templating functions instead of a model. Model classes cannot be added to light modules because light modules cannot contain their own Java classes. However, a light module can reference a from another module such as MTE.
A model can execute any Java code to retrieve data from the JCR repository or from an external source.
What is a model?
A model is written as a Java model class. It is a JavaBean where business logic resides. The model class is the entry point for custom Java logic for the template script. All templates - page, area and component - can define a model class.
How a model works?
During the rendering process, the renderer calls the model's
execute() before it calls the template script. The return value of the
execute method is passed to the template script with the
The model class:
- Is instantiated for each rendering process.
- Is provided to the respective script as an object model.
- Is provided the current content, the current page definition and any parent model.
All of the model's public methods can be accessed by the tempate script.
Benefits of using a model
There are a number of benefits to using a model:
- Provides a clean separation between script rendering and business logic. You can change business logic without changing rendering logic.
- Different page, area and component templates can use the same business logic.
- Interaction between template scripts and their models can be predefined during the conceptual project phase.
- Model classes and template scripts can be developed independently,
- Because the model is a Java class, you can use all Magnolia Java components.
- Model classes are reusable and can be subclassed.
- You can retain control of the business logic by preventing changes by front-end script developers.
Referencing a model
All templates can use a model class. The model class is referenced in the
modelClass property in the template definition.
Example: A home page template that uses a model class
Using model methods
Model classes provide their own methods. You can use any
public method in your templates. The methods are exposed using the
model.<method name> notation.
All getters without parameters can be accessed without the 'get' part of the method name and without the method brackets. Method that expect parameters can only be called by the full method declaration:
Below are examples of how to use model methods in your templates.
|Model class method||Script use|
These following objects are passed into the constructor of a model:
- current content: The content of the current rendered template.
- current definition: The template definition of the current rendered template.
- parent model: Is the parent model of the last render cycle.
The constructor of a model uses Java Generics. The used definition can be defined by generics. No casts are needed.