Write metadata "instructions"

Question

Hi
I´m trying to edit the metadata "instructions" in some photos vieweb by Bridge. At true, I need to preserve what´s already written in this field, then add some more things via script.
Here´s my try:
var doc = app.document;
doc.selectAll();
var sel = doc.getSelection ("psd, ai, tif, tiff, jpg, png, bmp, jpeg");
if (ExternalObject.AdobeXMPScript==undefined) ExternalObject.AdobeXMPScript = new ExternalObject("lib:AdobeXMPScript");
for (var g=0 ; g<sel.length ; g++){
     var xFile = new XMPFile (sel[g].spec.fsName, XMPConst.UNKNOWN, XMPConst.OPEN_FOR_UPDATE);
     var xmp = xFile.getXMP();
     var x = sel[g].metadata;
     var instruc = new String (x.read ("http://ns.adobe.com/photoshop/1.0/", "Instructions"));
     instruc = instruc + "<test bonus instruction>";
     //up to this line, everything is right
     xmp.deleteProperty (XMPConst.NS_XML, "instructions") //problem is this line and/or the line below. It does not return error, but do not write too.
     xmp.appendArrayItem(XMPConst.NS_XML, "instructions", instruc, 0, XMPConst.ARRAY_IS_ORDERED); //problem can be here.
if (xFile.canPutXMP(xmp)){
     xFile.putXMP(xmp);
     xFile.closeFile(XMPConst.CLOSE_UPDATE_SAFETY);
What Am I missing?
Thank you a lot for the help
Best Regards
Gustavo.

Answer 1

Gustavo… XMP is not one of my great strengths so I may well be wrong… Anyhows I don't this the instructions property is an Array but a simple String…
#target bridge
if ( loadXMPLibrary() ) { processThumbnails() };
if ( unloadXMPLibrary() ) { alert( 'were done' ) };
     Process the thumbnails in Bridge
function processThumbnails() {
     var i, count, doc, smd, inst;
     doc = app.document;
     count  = doc.visibleThumbnailsLength;
     for ( i = 0; i < count; i++ ) {
          if ( /\.(ai|bmp|jpg|jpeg|png|psd|tif+)$/.test( doc.visibleThumbnails[i].name ) ) {
               if ( doc.visibleThumbnails[i].hasMetadata ) {
                    smd = doc.visibleThumbnails[i].synchronousMetadata;
                    inst = smd.read( 'http://ns.adobe.com/photoshop/1.0/', 'Instructions' );
                    undateXMP( doc.visibleThumbnails[i], inst );
     Update the XMP properties…
function undateXMP( thumb, inst ) {
     var xmpFile, xmp;
     xmpFile = new XMPFile( thumb.spec.fsName, XMPConst.UNKNOWN, XMPConst.OPEN_FOR_UPDATE );
     xmp = xmpFile.getXMP();
     inst += ', elmo';
     // The line below returns an XMP error the property is NOT an Array…
     //xmp.appendArrayItem( 'http://ns.adobe.com/photoshop/1.0/', 'Instructions', XMPConst.PROP_IS_ARRAY, inst, XMPConst.ARRAY_IS_ORDERED );
     xmp.setProperty( 'http://ns.adobe.com/photoshop/1.0/', 'Instructions', inst, 0, XMPConst.STRING );
     if ( xmpFile.canPutXMP( xmp ) ) {
          xmpFile.putXMP( xmp );
          xmpFile.closeFile( XMPConst.CLOSE_UPDATE_SAFETY  );
     Load the XMP External Object Library
function loadXMPLibrary() {
     if ( !ExternalObject.AdobeXMPScript ) {
          try {
               ExternalObject.AdobeXMPScript = new ExternalObject( 'lib:AdobeXMPScript' );
               return true;
          } catch(e) { return false; };
     Unload the XMP External Object Library
function unloadXMPLibrary() {
     if ( ExternalObject.AdobeXMPScript ) {
          try {
               ExternalObject.AdobeXMPScript.unload();
               ExternalObject.AdobeXMPScript = undefined;
               return true;
          } catch(e) { return false; };