jsfsession-scopemanaged-property

Can't I access session scope variable using @ManagedProperty?


I know I can put/get session scope variables like this.

FacesContext.getCurrentInstance().getExternalContext()
    .getSessionMap().put(SESSION_KEY_SOME, some);

Then can't I access the value like this?

@ManagedBean
@SessionScoped
public class SomeOtherBean {

    @ManagedProperty("#{sessionScope.some}")
    private Some some;
}

The value is null.


Solution

  • @ManagedProperty runs during creation/instantiation of the @ManagedBean.

    So, when the @ManagedBean is created before the #{sessionScope.some} is set for first time, then it will still remain null in the @ManagedBean. It will only work when @ManagedBean is created after the #{sessionScope.some} is set for the first time.

    There are basically three ways to achieve the desired behavior.

    1. Replace private Some some by externalContext.getSessionMap().get("some").

      @ManagedBean
      @SessionScoped
      public class SomeOtherBean {
      
          public void someMethod() {
              Some some = (Some) FacesContext.getCurrentInstance()
                  .getExternalContext().getSessionMap().get("some");
              // ...
          }
      
      }
      
    2. Replace @SessionScoped by @RequestScoped.

      @ManagedBean
      @RequestScoped
      public class SomeOtherBean {
      
          @ManagedProperty("#{sessionScope.some}")
          private Some some;
      
          // ...
      }
      
    3. Replace externalContext.getSessionMap().put("some", some) by directly setting it as bean property.

      @ManagedBean
      public class SomeBean {
      
          @ManagedProperty("#{someOtherBean}")
          private SomeOtherBean someOtherBean;
      
          public void someMethod() {
              // ...
              someOtherBean.setSome(some);
          }
      
          // ...
      }
      

    See also: