(Ruby) PDF Update or Add XML Metadata

Demonstrates how to add or update the XML metadata stored in a PDF.

Note: This example requires Chilkat v10.1.0 or later.

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

# This requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

pdf = Chilkat::CkPdf.new()

# Load a PDF file.
# If the PDF file already has metadata, we'll update it.
# Otherwise this example adds the metadata.
success = pdf.LoadFile("qa_data/pdf/blank_with_metadata.pdf")
if (success == false)
    print pdf.lastErrorText() + "\n";
    exit
end

xml = Chilkat::CkXml.new()
sbExisting = Chilkat::CkStringBuilder.new()

hasMetadata = pdf.GetMetadata(sbExisting)
if (hasMetadata == true)
    xml.LoadSb(sbExisting,true)
else

    # Otherwise create the bare minimum XMP metadata.
    xml.put_Tag("x:xmpmeta")
    xml.AddAttribute("xmlns:x","adobe:ns:meta/")
    xml.AddAttribute("x:xmptk","Adobe XMP Core 9.1-c001 79.675d0f7, 2023/06/11-19:21:16 ")
    xml.UpdateAttrAt("rdf:RDF",true,"xmlns:rdf","http://www.w3.org/1999/02/22-rdf-syntax-ns#")
    xml.UpdateAttrAt("rdf:RDF|rdf:Description",true,"rdf:about","")
    xml.UpdateAttrAt("rdf:RDF|rdf:Description",true,"xmlns:xmp","http://ns.adobe.com/xap/1.0/")
    xml.UpdateAttrAt("rdf:RDF|rdf:Description",true,"xmlns:dc","http://purl.org/dc/elements/1.1/")
    xml.UpdateAttrAt("rdf:RDF|rdf:Description",true,"xmlns:xmpMM","http://ns.adobe.com/xap/1.0/mm/")
    xml.UpdateAttrAt("rdf:RDF|rdf:Description",true,"xmlns:pdf","http://ns.adobe.com/pdf/1.3/")
    xml.UpdateAttrAt("rdf:RDF|rdf:Description",true,"xmlns:xmpRights","http://ns.adobe.com/xap/1.0/rights/")

    dt = Chilkat::CkDateTime.new()
    dt.SetFromCurrentSystemTime()
    ts = dt.getAsTimestamp(true)

    xml.UpdateChildContent("rdf:RDF|rdf:Description|xmp:ModifyDate",ts)
    xml.UpdateChildContent("rdf:RDF|rdf:Description|xmp:CreateDate",ts)
    xml.UpdateChildContent("rdf:RDF|rdf:Description|xmp:MetadataDate",ts)

    xml.UpdateChildContent("rdf:RDF|rdf:Description|xmp:CreatorTool","My Custom Application")
    xml.UpdateChildContent("rdf:RDF|rdf:Description|dc:format","application/pdf")

    sbDocId = Chilkat::CkStringBuilder.new()
    sbDocId.Append("uuid:")
    sbDocId.AppendUuid(true)
    xml.UpdateChildContent("rdf:RDF|rdf:Description|xmpMM:DocumentID",sbDocId.getAsString())

    sbInstanceId = Chilkat::CkStringBuilder.new()
    sbInstanceId.Append("uuid:")
    sbInstanceId.AppendUuid(true)
    xml.UpdateChildContent("rdf:RDF|rdf:Description|xmpMM:InstanceID",sbInstanceId.getAsString())

end

# Add our custom metadata tags to either the existing XML metdata, or the newly created metadata.
xml.UpdateAttrAt("rdf:RDF|rdf:Description",true,"xmlns:zf","urn:ferd:pdfa:CrossIndustryDocument:invoice:1p0#")
xml.UpdateAttrAt("rdf:RDF|rdf:Description",true,"rdf:about"," ")
xml.UpdateChildContent("rdf:RDF|rdf:Description|zf:ConformanceLevel","BASIC")
xml.UpdateChildContent("rdf:RDF|rdf:Description|zf:DocumentFileName","ZZZZZZ-invoice.xml")
xml.UpdateChildContent("rdf:RDF|rdf:Description|zf:DocumentType","INVOICE")
xml.UpdateChildContent("rdf:RDF|rdf:Description|zf:Version","1.0")

# Create a new PDF with the updated metadata.
sb = Chilkat::CkStringBuilder.new()
xml.GetXmlSb(sb)
success = pdf.UpdateMetadata(sb,"c:/temp/qa_output/out.pdf")
if (success == true)
    print "Success" + "\n";
else
    print pdf.lastErrorText() + "\n";
end

# To see the metadata in Adobe Acrobat DC,
# 1) Open the PDF.
# 2) CTRL-D to show the Document Properties dialog.
# 3) In the dialog, click on the "Additional Metadata" button.
# 4) In the Additional Data dialog, click on "Advanced"
# 5) Expand the namespace tree for the metadata you added.

print "OK" + "\n";