Can't update ContentVersion. My code create new file every time

Question

I had such issue. I created method that save attachent to my Opportunity.

    public PageReference attachInvoicePDF() {
        /* Get the page definition */
        PageReference pdfPage = Page.Invoice_PDF_V2;
        
        pdfPage.getParameters().put('id', oppId);
        /* generate the pdf blob */
        Blob pdfBlob;
        if(Test.isRunningTest()) { 
            pdfBlob = blob.valueOf('Unit.Test');
          } else {
            pdfBlob = pdfPage.getContentAsPDF();
          }
        Attachment attach;
        Attachment[] a;
        //Get attachment
        a = [SELECT Id, Name, Body, ContentType, ParentId From Attachment WHERE parentId = :oppId];
        /* create the attachment for opportunity*/
        if (a.size() == 0) {
             attach = new Attachment(parentId = oppId, name=opportun.Invoice_Number__c + '.pdf', body = pdfBlob);
             insert attach;
        } else {
            attach = a[0];
        }

        //Insert ContentVersion
        ContentVersion cVersion = new ContentVersion();
        cVersion.ContentLocation = 'S'; 
        cVersion.PathOnClient = attach.Name;
        cVersion.Origin = 'C';
        //cVersion.OwnerId = attach.OwnerId;
        cVersion.Title = attach.Name;
        cVersion.VersionData = pdfBlob;
        Insert cVersion;
 
        //After saved the Content Verison, get the ContentDocumentId
        Id conDocument = [SELECT ContentDocumentId FROM ContentVersion WHERE Id =:cVersion.Id].ContentDocumentId;
 
        //Insert ContentDocumentLink
        ContentDocumentLink cDocLink = new ContentDocumentLink();
        cDocLink.ContentDocumentId = conDocument;
        cDocLink.LinkedEntityId = attach.ParentId;
        cDocLink.ShareType = 'V';
        cDocLink.Visibility = 'AllUsers';
        Insert cDocLink;

        return pdfPage;
    }  

I wrote test for this method and debug it. T\I see the problem here:

        a = [SELECT Id, Name, Body, ContentType, ParentId From Attachment WHERE parentId = :oppId];

I call two times my method in test. First time my method should use if block.

        if (a.size() == 0) {
             attach = new Attachment(parentId = oppId, name=opportun.Invoice_Number__c + '.pdf', body = pdfBlob);
             insert attach;
        } else {
            attach = a[0];
        }

And second call should use else block but it use if block again. Can you help me why my second call don't see inserted Attachment after first call?

Also I have two VF pages: Page.Invoice_PDF and Page.Invoice_PDF_V2

Because when I use one page, it creates infinite loop. Maybe the problem is here?

Answer 1

To add a new ContentVersion for an existing File, you have to provide the existing ContentDocumentId before insert as below.

<Identify the Existing ContentVersion based on some criteria>
<get the ContentDocumentId of the existing ContentVersion>
  
ContentVersion cv = new ContentVersion();
....
....
if(<match found>){
    cv.ContentDocumentId = <existing ContentDocumentId>;
    insert cv;
} else {
    insert cv;
    <get the ContentDocumentId>
    <Insert ContentDocumentLink with the ContentDocumentId>
}