Download a VF page as pdf with a button

Question

I want to have a button that dowload a pdf page as a file related to the record from where I pressed the button. My page is working well, but I had to add a controller so clicking on the button download the page instead of showing me the page. I know that A way to do it is to creating a second VF page that will call the "real" page I want. But I prefered to find a way where I only needed to add a parameter to the page for the problem where the getContent() method call a new page that calls a new page and so on.

here is the code of my controller I greatly inspired myself from this question for my code

public class certificateDownloader {
    public ApexPages.StandardController stdController {get; set;}

    public certificateDownloader(ApexPages.StandardController controller){
        stdController = controller; 
    }

    public pageReference downloadPdf2() {
        if (!Test.isRunningTest()) {//when accessing by a record
            if (ApexPages.currentPage().getParameters().get('doNotSavePDF') == null) {
                ApexPages.currentPage().getParameters().put('doNotSavePDF', 'true');
                Blob certificatePdf = ApexPages.currentPage().getContent();
                Attachment file = new Attachment(parentId = stdController.getId(), Name='test.pdf', body=certificatePdf);
                insert file;
            }
        
            PageReference page = stdController.view();
            page.setRedirect(true);
            return page;
        }
        else {return null;}
    }
}

here is the VF page:

<apex:page standardController="WorkOrder" renderAs="pdf" showHeader="false" standardStylesheets="false" extensions="certificateDownloader" action="{!downloadPdf2}">
stuff
</apex:page>

but for some reason the pdf downloaded as an Attachment is not working and seems corrupted each time I try opening it. I don't think the problem is with my VFpage, since it works well when I emove the action parameter from the <apex:page>

EDIT : using getContentAsPdf() method isn't working either, the pdf it gives me is blank, and it doesn't change if I change the renderAs parameter in <apex:page>.

Answer 1

You need to render the page as PDF in Apex, not just on the page:

if (ApexPages.currentPage().getParameters().get('doNotSavePDF') == null) {
  
  PageReference myPage = Page.CURRENT_PAGE_NAME;
  myPage.getParameters().put('doNotSavePDF', 'true');
  Id woId = ApexPages.currentPage().getParameters().get('Id');
  myPage.getParameters().put('Id', woId);
  Blob certificatePdf = myPage.getContent();
  Attachment file = new Attachment(parentId = stdController.getId(), Name='test.pdf', body=certificatePdf);
  insert file;
}

This will save the PDF as an attachment.

Don't return anything from the method. Just return null. It should insert the attachment AND show the page as a PDF to the user.