Model Driven

Struts 2 does not have "forms" like Struts 1 did. In Struts 2 request parameters are bound directly to fields in the actions class, and this class is placed on top of the stack when the action is executed.

If an action class implements the interface com.opensymphony.xwork2.ModelDriven then it needs to return an object from the getModel() method. Struts will then populate the fields of this object with the request parameters, and this object will be placed on top of the stack once the action is executed. Validation will also be performed on this model object, instead of the action.

Interceptor

To use ModelDriven actions, make sure that the Model Driven Interceptor is applied to your action. This interceptor is part of the default interceptor stack defaultStack so it is applied to all actions by default.

Example

Action class:

 
             public 
              class 
              ModelDrivenAction 
             implements 
              ModelDriven { 
            
             public 
              String execute() 
             throws 
              Exception {
            
             return 
              SUCCESS;
            
             }
            
             public 
              Object getModel() {
            
             return 
              new 
              Gangster();
            
             }
            
             }

Gangster class (model):

 
             public 
              class 
              Gangster 
             implements 
              Serializable {
            
             private 
              String name;
            
             private 
              int 
              age;
            
             private 
              String description;
            
             private 
              boolean 
              bustedBefore;
            
             public 
              int 
              getAge() {
            
             return 
              age;
            
             }
            
             public 
              void 
              setAge(
             int 
              age) {
            
             this
             .age = age;
            
             }
            
             public 
              boolean 
              isBustedBefore() {
            
             return 
              bustedBefore;
            
             }
            
             public 
              void 
              setBustedBefore(
             boolean 
              bustedBefore) {
            
             this
             .bustedBefore = bustedBefore;
            
             }
            
             public 
              String getDescription() {
            
             return 
              description;
            
             }
            
             public 
              void 
              setDescription(String description) {
            
             this
             .description = description;
            
             }
            
             public 
              String getName() {
            
             return 
              name;
            
             }
            
             public 
              void 
              setName(String name) {
            
             this
             .name = name;
            
             }
            
             }

JSP for creating a Gangster:

 
             <
             s:form 
              action="modelDrivenResult" method="POST" namespace="/modelDriven">   
            
             <
             s:textfield 
              label="Gangster Name" name="name" />
            
             <
             s:textfield 
              label="Gangster Age"  name="age" />
            
             <
             s:checkbox  
              label="Gangster Busted Before" name="bustedBefore" />
            
             <
             s:textarea  
              cols="30" rows="5" label="Gangster Description" name="description" />            
            
             <
             s:submit 
              />
            
             </
             s:form
             >