JSF scopes guidelines (draft notes...)

Request Scope
I request page foo.xhtml?myArg=1 (with GET method)...Then in foo.xhtml or its binding bean (FooBean.java) I can access myArg from request scope.


Flash Scope

When you want a variable to persist after a post-back use flash.

Example: foo.xhtml has inputText with id myInputText...I hit commandButton and action/actionListener submitData() is executed...I return to foo.xhtml and want the updated value of myInputText...then in  submitData() you should save myInputText value in flash

TODO: to elaborate more with examples...

Request vs Flash Scopes

• In request scope you can access everything included in a HTTP GET request for a new page
• In flash scope you can access
• same as request scope (i.e. everything in request after a HTTP GET request)
• everything in request after a JSF postback (HTTP POST request)
• everything in request after a redirect

How to read from / write to Request Scope
From web page:

#{request.id}

From backing bean:

Map requestMap = FacesContext.getCurrentInstance().getExternalContext().getRequestMap();
requestMap.get("id");
requestMap.put("id",1);

How to read from / write to Flash Scope

From web page:

#{flash.id}
 [but makes no sense]

From backing bean:

Flash flash = FacesContext.getCurrentInstance().getExternalContext().getFlash();
flash.get("id");
flash.put("id",1);