(Go) 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.

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

    pdf := chilkat.NewPdf()

    // 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 {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        return
    }

    xml := chilkat.NewXml()
    sbExisting := chilkat.NewStringBuilder()

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

        // Otherwise create the bare minimum XMP metadata.
        xml.SetTag("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.NewCkDateTime()
        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.NewStringBuilder()
        sbDocId.Append("uuid:")
        sbDocId.AppendUuid(true)
        xml.UpdateChildContent("rdf:RDF|rdf:Description|xmpMM:DocumentID",*sbDocId.GetAsString())

        sbInstanceId := chilkat.NewStringBuilder()
        sbInstanceId.Append("uuid:")
        sbInstanceId.AppendUuid(true)
        xml.UpdateChildContent("rdf:RDF|rdf:Description|xmpMM:InstanceID",*sbInstanceId.GetAsString())

    }

    // 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.NewStringBuilder()
    xml.GetXmlSb(sb)
    success = pdf.UpdateMetadata(sb,"c:/temp/qa_output/out.pdf")
    if success == true {
        fmt.Println("Success")
    } else {
        fmt.Println(pdf.LastErrorText())
    }

    // 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.

    fmt.Println("OK")

    pdf.DisposePdf()
    xml.DisposeXml()
    sbExisting.DisposeStringBuilder()
    dt.DisposeCkDateTime()
    sbDocId.DisposeStringBuilder()
    sbInstanceId.DisposeStringBuilder()
    sb.DisposeStringBuilder()