Passing method parameters with apex:actionFunction

Question

I have this Visualforce code snippet in a page:

<apex:outputLink value="javascript:if (window.confirm('Are you sure?')) DeleteQuoteLineItem('{!LineItem.QuoteLineItem.Id}');">
    Del
</apex:outputLink>

<apex:actionFunction action="{!DeleteQuoteLineItem}" name="DeleteQuoteLineItem" reRender="content">
    <apex:param value="test"/>
</apex:actionFunction>

The two methods I'm using for testing are:

public void DeleteQuoteLineItem(String RecordID)
{
    System.debug('method with a paramater');
    System.debug(RecordID);
}

public void DeleteQuoteLineItem()
{
    System.debug('method without a parameter');
}

Everytime I click on the link to execute the apex:actionFunction, it's calling the DeleteQuoteLineItem() method without any parameter. I looked online and it seems like I need to create a class attribute and use assignTo= in my apex:param to populate it accordingly.

Is it possible to prevent this behavior and use standard method parameters, so I don't have to create class attributes? I want to work on a clean and optimized codebase, preventing unnecessary variable scope (so no class attribute when it's not required) and improve code re-usability by staying context agnostic.

Thanks

Answer 1

You can access the param that was passed directly inside you controller using the ApexPages class or the system class.

VF

<apex:outputLink value="javascript:if (window.confirm('Are you sure?')) DeleteQuoteLineItem('TEST VALUE');">
    Del
</apex:outputLink>

    <apex:actionFunction action="{!DeleteQuoteLineItem}" name="DeleteQuoteLineItem" reRender="content">
        <apex:param name="myParam" value=""/>
    </apex:actionFunction>

Apex

public void DeleteQuoteLineItem(){

    //either of the next 2 lines will work, 
    string passedParam1 = Apexpages.currentPage().getParameters().get('myParam');
    string passedParam2 = system.CurrentPageReference().getParameters().get('myParam');
    system.debug(passedParam1);
    system.debug(passedParam2);
}

Im just curious as to why you are opposed to using class properties to assign the params to. Both ways will work, just curious if you have a unique use case or just curious of other ways of accomplishing it. Hope this helps

Answer 2

If you want to pass data which does not require scope within the whole controller class, but rather requires to be visible only in the scope of called controller method, maybe you could consider using apex js remoting? E.g. your example with the js remoting approach might look like:

VF page:

<apex:outputLink value="javascript:if (window.confirm('Are you sure?')) DeleteQuoteLineItem('TEST VALUE');">
    Del
</apex:outputLink>

<script type="text/javascript">
    function DeleteQuoteLineItem(param) {
        Visualforce.remoting.Manager.invokeAction(
            '{!$RemoteAction.MyController.DeleteQuoteLineItem}', 
            param, 
            function(result, event){
                if (event.status) {
                    DeleteQuoteLineItemCallback();
                } else if (event.type === 'exception') {
                    // handle exception
                } else {
                    // handle error
                }
            }
        );
    }
</script>
<apex:actionFunction name="DeleteQuoteLineItemCallback" reRender="content"></apex:actionFunction>

...while your controller should contain this method:

@RemoteAction
public static void DeleteQuoteLineItem(string param) {
    system.debug(param);
}

The solution above does however have one drawback - in order for the content outputPanel (or whichever component it is) to be rerendered, success callback for the initial remote method call will invoke yet another actionFunction, whose sole purpose is to rerender the content panel.

Maybe could be done a bit tidier, but nothing comes to mind at the moment :)