How to attach a file using x++

To attach a file to a record you can use the following code snippet.
The class to use is the following: DocumentManagement::attachFileToCommon()

var mime = System.Web.MimeMapping::GetMimeMapping(filename);
DocuRef docrefOut = DocumentManagement::attachFileToCommon(
                            commonRec,
                            DocuType::typeFile(),
                            memStreamIOArExpo,
                            filename,
                            mime,
                            filename);

An example of use can be seen in the splitEROutputByItems method of the EMActionERExport class.