Hello all.

I have an interface class called ReceiptBatch with two implementations: ReceiptBatch_charitable and ReceiptBatch_convertExisting. Most of the time I will use _charitable.  _convertExisting is a temporary implementation which will be used only by the admin (me) for a very short period of time to convert existing records to the new format.

I am trying to create a way to stealthily change the implementation used when accessing the visualforce page. My current attempt is to pass a URL query parameter when accessing the page, as in /apex/ReceiptBatch?rtype=convert. If that parameter exists in the URL then the controller extension will instantiate the _convertExisting implementation, otherwise it will default to the _charitable implementation.

Here's a summary of my current logic.

1. The visualforce page uses StandardSetController to select a list of Opportunities for processing
2. In the controller extension's constructor, check for the querystring parameter. If it exists, assign to a public variable which is bound to a hidden field on the form to maintain the parameter between page posts
3. If the hidden field contains a value, then use that to instatiate the appropriate implementation, otherwise instantiate the default

Using the logs, I have verified that the parameter is being read from the query string and saved to the hidden field but it doesn't carry through to the final form submission and the processing is always completed using the default implementation. How can I get that parameter to persist to the final form submission? Any help is greatly appreciated.

Here's the code. I have underlined the parts most relevant to this question.

Visualforce Page:

<apex:page standardController="Opportunity" extensions="ReceiptBatch_controller" recordSetVar="opportunities" action="{!validateOpps}">
    
    <apex:form >
        <apex:pageBlock rendered="{!cleanOpps.size > 0}">
            <p style="background-color:green;color:white;padding:3px;"><b>Receipts may be generated for the following opportunities</b></p><br/>
            <apex:pageBlockTable value="{!cleanOpps}" var="c" id="cleanList">
                <apex:column value="{!c.CharitableReceipt__c}"/>
                <apex:column value="{!c.Account.Name}"/>
                <apex:column value="{!c.Name}"/>
                <apex:column value="{!c.Amount}"/>
                <apex:column value="{!c.CloseDate}"/>
                <apex:column value="{!c.IsWon}"/>
            </apex:pageBlockTable>

            Address the receipt to: 
            <apex:selectList multiselect="false" size="1" value="{!addresseeType}">
                <apex:selectOptions value="{!addresseeTypeList}"></apex:selectOptions>
            </apex:selectList>
            <apex:inputHidden value="{!ReceiptType}"/>
            <apex:commandButton action="{!issueNew}" value="Yes, create receipts for these opportunities"/>
        </apex:pageBlock>
</apex:form>
    
    <apex:pageBlock rendered="{!dirtyOpps.size > 0}">
        <p style="background-color:red;color:white;padding:3px;"><b>The following opportunities are invalid because:</b> {!ValidationMessage}<br/>
        You may correct any errors and rebuild your selection below</p><br/>
        
        <apex:pageBlockTable value="{!dirtyOpps}" var="d" id="dirtyList">
            <apex:column value="{!d.CharitableReceipt__c}"/>
            <apex:column value="{!d.Account.Name}"/>
            <apex:column value="{!d.Name}"/>
            <apex:column value="{!d.Amount}"/>
            <apex:column value="{!d.CloseDate}"/>
            <apex:column value="{!d.IsWon}"/>
        </apex:pageBlockTable>
    </apex:pageBlock>   

    <apex:pageBlock >
        <apex:listViews type="Opportunity"/>
    </apex:pageBlock>  
    
</apex:page>

Controller Extension:

public with sharing class ReceiptBatch_controller{
    
    private ApexPages.StandardSetController itsStandardSetController;
    private List<Opportunity> itsSelectedOpps;
    private List<Opportunity> itsCleanOpps;
    private List<Opportunity> itsDirtyOpps;
    private List<CharitableReceipt__c> itsNewReceipts;
    private String itsValidationMessage;
    private ReceiptBatch_interface rbatch;

    public String receiptType{get;set;}
    public String addresseeType{get;set;}
    
    public List<SelectOption> addresseeTypeList{
        get{
            List<SelectOption> a = new List<SelectOption>();
            a.add(new SelectOption('Account','Account'));
            a.add(new SelectOption('Contact','Contact'));
            a.add(new SelectOption('Household','Household'));
            return a;
        }
    }
    
    public List<Opportunity> cleanOpps{
        get{return itsCleanOpps;}
        private set;
    }
    
    public List<Opportunity> dirtyOpps{
        get{return itsDirtyOpps;}
        private set;
    }  
    
    public String validationMessage{
        get{return itsValidationMessage;}
        private set;
    }
    
    public List<CharitableReceipt__c> newReceipts{
        get{return itsNewReceipts;}
        private set;
    }
    
    public ReceiptBatch_controller(ApexPages.StandardSetController sC){
        itsStandardSetController = sC;
        
        if (ApexPages.currentPage().getParameters().get('rtype') != null){
            receiptType = ApexPages.currentPage().getParameters().get('rtype');
        }
        
        if(receiptType == 'convert'){
            rbatch = new ReceiptBatch_convertExisting();
        } else if(receiptType == 'charitable'){
            rbatch = new Receiptbatch_charitable();
        } else {
            rbatch = new Receiptbatch_charitable();
        }
        
    }
    
    public void validateOpps(){
        itsSelectedOpps = itsStandardSetController.getSelected();
        rbatch.setOpportunities(itsSelectedOpps);
        itsCleanOpps = rbatch.getCleanOpportunities();
        itsDirtyOpps = rbatch.getDirtyOpportunities();
        itsValidationMessage = rbatch.getValidationMessage();
    }
    
    public void issueNew(){
        rbatch.setAddresseeType(addresseeType);
        rbatch.issueReceipts();
        itsNewReceipts = rbatch.getNewReceipts();
     }

}