Exploring Link.relink() function in Javascript and COM

Some days ago I needed to change my automation tool written in C# as Windows application. The reason was that we use Dropbox now and all pages opened on another computer have a whole bunch of missing links due to different Dropbox folder locations.

Updating links in Javascript is easy and if I do it from Indesign I use following script:

var alllinks = app.activeDocument.links;
for (var i = 0; i < alllinks.length; i++)
{
    var cur_link = alllinks[i];
    {
        var m = cur_link.filePath.match(/.+Dropbox\\(.+)/);
        if (m)
        {
            try
            {
                cur_link.relink(File('W:\\' + m[1]));
            }
            catch (e)
            { }
        }

    }
}

where W: is my Dropbox folder mapped as drive letter.

But as I tried to implement the same logic in my application using COM access

var allLinks = Doc.Links;
for (int i = 1; i <= allLinks.Count; i++)
{
Link l = allLinks[i];
if (l.Status == idLinkStatus.idLinkMissing)
{
string lp = (string) l.FilePath;
if (lp.IndexOf("Dropbox", StringComparison.Ordinal) > -1)
try
{
l.Relink(Regex.Replace(lp, ".+Dropbox", "W:"));
}
catch (COMException)
{
// ignored
}
}
}

I found that it doesn't work - relink function doesn't accept the new filename as string.

So I decided to look a little closer at the Javascript relink() function.

DOM defines it as following:

Link.relink (to:varies)

Adobe InDesign 2020 (15.0) Object Model

Points the link to a new source file.

to: Data Type: varies

The full path name of the new source file. Can accept: File or String.

In case of File it works perfectly and I am sure all of you use it in your scripts:

relink(File(newfilename));

But what about String?

I made a test page with missing image (d:\test\missing.jpg) and a test script:

var alllinks = app.activeDocument.links;
var newlink = "d:\\test\\test.jpg";
for (var i = 0; i < alllinks.length; i++)
{
    var cur_link = alllinks[i];
	$.writeln(cur_link.filePath + ' - ' + cur_link.status.toString());
        if (cur_link.status == LinkStatus.LINK_MISSING)
        {
            try
            {
                cur_link.relink(newlink);
		$.writeln(cur_link.filePath + ' - ' + cur_link.status.toString());
            }
            catch (e)
            { }
        }	
}

where I used a filename string as argument for relink().

Result:

d:\test\missing.jpg - LINK_MISSING

The function shows no error but does nothing and just goes to next loop iteration.

Changing the line

cur_link.relink(newlink);

to

cur_link.relink(File(newlink));

I got a working function:

d:\test\missing.jpg - LINK_MISSING
D:\test\test.jpg - NORMAL

So what does Adobe mean with the String and how could I get the right string in C#?

After some tests I have found the answer!

DOM should define the function argument as following:

The full path name of the new source file. Can accept: File or Uri String.

Indeed, if I change the filename string to Uri

cur_link.relink('file:' + newlink);

the script is working again:

d:\test\missing.jpg - LINK_MISSING
d:\test\test.jpg - NORMAL

Now I can use it in my C# code:

l.Relink($"file:{Regex.Replace(lp, ".+Dropbox", "W:")}");

Is the problem solved now? No.

The above solution works only if the new filename/path has no spaces.

As I deal with German filenames, it means

The above solution works only if the new filename/path has no umlauts.

So it wasn't a solution at all.

I needed to convert the new path to a valid Uri string.

That wasn't too complicate. In Javascript:

cur_link.relink('file:' + encodeURI(newlink));

In C#:

l.Relink($"file:{Uri.EscapeUriString(Regex.Replace(lp, ".+Dropbox", "W:"))}");

Result:

d:\test\missing.jpg - LINK_MISSING
d:\test\test.jpg - NORMAL

I added another missing image to my test page to test the solution in a loop.

Result:

d:\test\missing.jpg - LINK_MISSING
d:\test\test.jpg - NORMAL
d:\test\missing.jpg - LINK_MISSING
d:\test\test.jpg - NORMAL

Victory! 🙂

To make my research complete, I tested the new reinitLink() function, which is stated as experimental.

cur_link.reinitLink('file:' + encodeURI(newlink));

Result:

d:\test\missing.jpg - LINK_MISSING
d:\test\test.jpg - LINK_OUT_OF_DATE
d:\test\test.jpg - LINK_OUT_OF_DATE

So, this function replaces link paths but doesn't update links.

I hope, this information might be useful. 🙂