Visualforce: Adding CSS class from Controller

Question

Is it possible to add a CSS class to one of the Visualforce page objects from controller? What I want to achieve is to handle one exception in controller. From catch block I want to be able to hide a form (add a CSS class to form with display:hidden).

Answer 1

Create a variable in your controller,

public boolean isVisible{gt;set;}

assign it true/false depending on condition(exception in your case)

surround form you want to show by an output panel

<apex:outputPanel rendered="{!isVisible}">
<apex:form>
.
.
.
.
</apex:form>
</apex:outputPanel>

Answer 2

You can assign a class name to the variable and then dynamically assign a new value:

Apex Class:

public with sharing class MyController{

    public String myCSSClass {get; set;}

    public MyController(){
        myCSSClass = 'visible';
    }

    public PageReference myMethod{
        try{
            ...
        }
        catch{
            myCSSClass = 'hidden';
        }

            return null;
    }
}

Visualforce page: after user clicks on the "Check" button a method "myMethod" called. If it fails the variable gets a "hidden" class.

<style>
.visible{
    display:block;
}
.hidden{
    display:none;
}
</style>

<apex:commandButton action="{!myMethod}" value="Check" reRender="myPanel">

<apex:outputPanel id="myPanel" styleClass="{!myCSSClass}">
...
</apex:outputPanel>