Displaying ApexPages.Messages on redirected VisualForce Page

Question

I hope this is a simple problem and I'm just missing something.

My Controller is something like this

public pagereference processtempcon(){
    //some code here
    delete record;
    pagereference p = apexpages.Currentpage();
    p.setredirect(true);
    apexpages.Message msg = new Apexpages.Message(ApexPages.Severity.Info,'Total Number of Records Processed:' + selectedtempcon.size());
    apexpages.addmessage(msg);
    return p; 
}

Which is not supported.Any Idea on this

Answer 1

So you want to reload the page an show some info in the message box. The setRedirect(true) parameter removes the info you want to show:

If set to true, a redirect is performed through a client side redirect. This type of redirect performs an HTTP GET request, and flushes the view state

I have created a simple example and it works fine:

Controller:

public with sharing class test1{
    public Integer myInt { get; set; }
    public test1(){
        myInt = 0;
    }
    public pagereference processtempcon(){
        pagereference p = apexpages.Currentpage();
        apexpages.Message msg = new Apexpages.Message(ApexPages.Severity.Info,'Total Number of reloads: ' + (myInt++));
        apexpages.addmessage(msg);
        return p; 
    }
}

Page:

<apex:page controller="test1">
    <apex:form >
        <apex:messages/>
        <apex:commandButton action="{!processtempcon}" value="Reload"/>
    </apex:form>
</apex:page>

Result:

Answer 2

Unless you want to re-run the constructor you might be better off not returning a page reference in your function. It has the same result as returning the page reference for the current page. For example

public void processtempcon(){
    //some code here
    ApexPages.Message msg = new Apexpages.Message(ApexPages.Severity.Info,'Total Number of Records Processed:' + selectedtempcon.size());
    Apexpages.addMessage(msg); 
}

If you want to selectively return users to a different page or to the same page you can switch from a void return type to a PageReference return type, but just return null. For example

public PageReference processtempcon(){
    //some code here
    if(selectTempCon.isEmpty()) {
       return Page.AnotherPage;
    } else {
      ApexPages.Message msg = new Apexpages.Message(ApexPages.Severity.Info,'Total Number of Records Processed:' + selectedtempcon.size());
      ApexPages.addmessage(msg);
      return null; // keeps the user on the current page
    } 
}