Passing parameters with commandButton

Question

I'm trying to pass a parameter with a commandButton. I've seen a few ways to do it on the net, but they don't work. What I have now:

<apex:commandButton value="Accept" action="{!acceptDeal}" disabled="{!d.buttonsAreDisabled}">
    <apex:param name="deal" value="{!d.theDeal}" assignTo="{!deal}"/>
</apex:commandButton>

the parameter is not being passed through. Many posts suggest to add reRender to my commandButton, but when I try that

<apex:commandButton value="Accept" action="{!acceptDeal}" disabled="{!d.buttonsAreDisabled}" rerender="someRerenderText">
    <apex:param name="deal" value="{!d.theDeal}" assignTo="{!deal}"/>
</apex:commandButton>

I get the following error:

Visualforce Error

A String, Number, or Boolean is required for attribute 'value' in <apex:param>.

Another option was to change commandButton to commandLink with styleClass="btn" attribute, but commandLink does not have disabled attribute that I need.

Answer 1

As the error message explains, apex:param can only handle primitive values not whole objects. Your description of types isn't entirely clear to me but something like this:

<apex:param name="deal" value="{!d.theDeal.Id}" assignTo="{!deal.Id}"/>

will work if d.theDeal is an SObject and if the deal property is pre-populated with a Deal__c object. Or you might choose to add a separate dealId property to the controller (of type ID):

<apex:param name="deal" value="{!d.theDeal.Id}" assignTo="{!dealId}"/>

so it is clearer what is going on.

Answer 2

I faced a similar problem. Although I couldn't find the reason why, but it was solved when I just added reRender="". I put nothing inside the quotes. I read on one of the posts that this is a mandate for the param to go through. Although I still don't know why. It worked in my case though. Hope it works for you too.