JSF El expression retaining old value (JSF life cycle)

Question

I have create a test project with JSF2.0 and richfaces. I am trying to plot chart. Now, I got value from database to bean and to datatable. Now when I wanted to pass this value to javascript varible and found this answer from The BalusC very userful. It works fine but the value that javascript variable gets after oncomplete="jsonDemo('#{kpilist.json}')". i.e. the value of #{kpilist.json} is not up-to-date it's last one.

I have printed the value of #{kpilist.json}. If it's printed afer datatabe the value is current. If it's printed before datatable it's last value. Any way since oncomplete attribute of a4j:ajax executes after eveything is completed why doesn't #{kpilist.json} show latest value? What is the order of execution of various listener and oncomplete attributes of richfaces and jsf component?

My Managed Bean:

@ManagedBean(name = "kpilist")
@ViewScoped
public class KPIListController implements Serializable {

    private static final long serialVersionUID = 1L;
    boolean state = true;
    String selectedKPIType;
    String selectKPITime = "D";
    boolean renderDatatable;
    String json;



    public String getJson() {
        return json;       
    }


    public boolean isRenderDatatable() {
        return renderDatatable;
    }

    public void setRenderDatatable(boolean renderDatatable) {
        this.renderDatatable = renderDatatable;
    }

    public boolean isState() {
        return state;
    }

    public List showViewList() {
        Logger.getLogger(KPIListController.class.getName()).warning("Show view List:");
        KPIDAO kpiDAO = new KPIDAO();
        try {
            Logger.getLogger(KPIListController.class.getName()).info("Into show view List ---select One");
            return kpiDAO.showViewList(selectKPITime);
        } catch (SQLException ex) {
            ex.printStackTrace();
            Logger.getLogger(KPIListController.class.getName()).log(Level.SEVERE, null, ex);
            return null;
        }
    }

    public void setState(boolean state) {
        this.state = state;
    }

    public String getSelectedKPIType() {
        return selectedKPIType;
    }

    public void setSelectedKPIType(String selectedKPIType) {
        this.selectedKPIType = selectedKPIType;
    }

    public String getSelectKPITime() {
        return selectKPITime;
    }

    public void setSelectKPITime(String selectKPITime) {
        this.selectKPITime = selectKPITime;
    }

    public List getKPI() {
        Logger.getLogger(KPIListController.class.getName()).warning("Get KPI Values:");
        KPIDAO kpiDAO = new KPIDAO();        
         List kpiList = new ArrayList();

        try {
            kpiList = kpiDAO.getKPI(selectedKPIType);  
            Logger.getLogger(KPIListController.class.getName()).warning("KPI List:"+kpiList.size());            

        } catch (SQLException ex) {
            ex.printStackTrace();
            return null;
        }
         Gson gson = new Gson();
        json= gson.toJson(kpiList);
        return kpiList;
    }

    public void resetFormValues() {       
        Logger.getLogger(KPIListController.class.getName()).warning("Reset form:");
        selectedKPIType = "--";
    }
}

My View:


    

    
    
        
            KPI Index
            

                   
                
                
                

                
                
                 
                 

                
                    
                    
                        
                        
                            
                         
                    

                    
                    
                        
                        
                         
                    

                    

                
                

                                                    

                            
                                
                                    
                                
                                
                            

                        
                    JSON String :

Javascript:

function jsonDemo(jsonString){

    console.log("Chart data already retrieved: " + jsonString);
    var data = $.parseJSON(jsonString);    
    $.each(data,function(i,val){
         console.log("The value of i: "+i+" The val: "+val.NCELLCLUSTER);
    });

}

BalusC · Accepted Answer

The EL expression in your oncomplete is evaluated at the moment the HTML/JS code is generated by JSF (thus, on the initial HTTP request). It's not evaluated at the moment the oncomplete is executed in JS as you seem to expect. It's not the webbrowser who evaluates EL expressions, it's the webserver. The oncomplete is by the way just executed after render. With a HTTP traffic debugger and a JS debugger (press F12 in Chrome/IE9/Firebug) you can easily track it.

There are several possibilities to solve this:

Just invoke a $.get() or $.getJSON() in jQuery and do the job in a normal servlet instead, or better, a JAX-RS webservice.
```
function jsonDemo() {
    $.getJSON("servletURL", function(jsonData) {
        // ...
    });
}
```
Replace the oncomplete by some which you render/update by ajax.
```
...

    jsonDemo(#{bean.json});
```

Unrelated to the concrete problem, you've there by the way a conceptual mistake as to passing around JSON data. You're stringifying it while passing as argument like so jsonDemo('#{kpilist.json}') and then you're parsing the JSON afterwards using $.parseJSON(). This makes no sense. Remove those singlequotes around the argument like so jsonDemo(#{kpilist.json}) and then you don't need that $.parseJSON() line anymore. The data is then already in JSON format.

JSF El expression retaining old value (JSF life cycle)

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