VF controller redirect to another page

Question

I have a Apex Controller for a VF page. I want to redirect my page to another one, only if I cannot get a specific parameter from the URL. current page: /apex/demo?param=123 -> stay on this page. current page: /apex/demo -> redirect to /apex/demo2.

My controller's constructor:

public demoController(){
String p = ApexPages.currentPage().getParameters().get('param');
if(p == null){
// redirect to /apex/demo2
}
}

How can I get it done? Thanks!

Answer 1

I figured out that I can use apex:page action="". VF:

<apex:page controller="demoController" action="{!redirect}"/>

Controller:

public PageReference redirect(){
        if(p == null){
            PageReference pageRef = new PageReference('/apex/demo2');
            return pageRef;
        }
        else{
            return null;
        }
}

Answer 2

You can use cookies

Set cookie

Cookie elementMsg = new Cookie('msg','true','/apex/pageYouAreGoingToUse',10,false);

Add to the current page

ApexPages.currentPage().setCookies(new Cookie[]{elementMsg});

Redirect to the page you want

return new PageReference('/apex/CompetencyAssessmentOne?id=' + Assessment.id );

Take the cookie from the page you are going to use the cookie

Cookie elementMsg = ApexPages.currentPage().getCookies().get('msg');

Use the cookie

        if(elementMsg != null){

        if(elementMsg.getValue().equals('true')){
            elementMsg = new Cookie('msg','true',null,0,false);
            ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.CONFIRM, 'Elements saved'));
        }
    }

Answer 3

I would recommend you to read through this doc to understand how pagereference works in apex:

https://www.salesforce.com/us/developer/docs/apexcode/Content/apex_system_pagereference.htm

Coming to your question this should do what you want:

public demoController(){
String p = ApexPages.currentPage().getParameters().get('param');
if(p == null){
callpageredirect();
}
}
public pagereference callpageredirect(){
PageReference demoPage = new pagereferenct('/apex/demo2');
    demoPage.setRedirect(true);
    return demoPage;
}