Can I have PageReference within PageReference?

Question

I am working on this requirement. I have a SaveAction() pagereference method in my controller on the Button click from the Input VF Page, where I am saving the VF page's input field values to an opportunity.

After the opportunity insert, I am calling another pagereference method within this SaveAction() to generate a PDF (from renderAs = "pdf") from a second VF page, i.e. PDFViewer. Here I am just referencing the fields values that are set in the actual VF page. But, every time, I get an empty valued initial VF page, but not the rendered as PDF page? Am I am missing something?

public PageReference SaveAction() {
   //insert Opp based on the values from the Input VF page.
    generatePDF();
    return null;
}

public PageReference generatePDF(){
    List<Attachment> attList = new List<Attachment>();
    PageReference pr = Page.PDFViewer;
    Blob pdfAsBody;
    if (!Test.isRunningTest()) {
        pdfAsBody = pr.getContentAsPDF();
    } else {
        pdfAsBody = Blob.valueOf('Dummy data');
    }

    Attachment att = new Attachment();
    att.Body = pdfAsBody;
    att.parentId = opp.Id;
    att.Name = 'attachment.pdf';
    attList.add(att);

    //Inserting the attachment. 
    if(!attList.IsEmpty()){
        insert attList;
    }
    return pr;
}

Answer 1

If the desired action when clicking a button/link associated with action method SaveAction is to return to the user a PDF page:

public PageReference SaveAction() {
   //insert Opp based on the values from the Input VF page.
    PageReference pdfPage = generatePDF();
    pdfPage.setRedirect(true);
    pdfPage.getParameters().put('Id',someId);  // to tell controller the object
    return pdfPage;
}