How can I check for existence of Itunes track in Applescript without throwing error

Question

the idea of this script (simplified to show the issue) is checks if a track exists,

    tell application "iTunes"
        set matchtrack to get first track in playlist 1 whose persistent ID is "F1A68AD90AA66648"
        if matchtrack is not {} then
            print name of matchtrack
        else
            print "no track found"
        end if
    end tell

unfortunately if the track does not exist it gives error

"iTunes got an error: Can’t get track 1 of playlist 1 whose persistent ID = \"F1A68AD90AA66648\"." number -1728 from track 1 of playlist 1 whose persistent ID = "F1A68AD90AA66648"
'

instead of just printing 'no track found'

Answer 1

get first track give a track object or an error

tracks give a list of one track or an empty list

tell application "iTunes"
    set matchtrack to tracks in playlist 1 whose persistent ID is "F1A68AD90AA66648"
    if matchtrack is not {} then
        return name of item 1 of matchtrack
    else
        return "no track found"
    end if
end tell

Answer 2

Simplest way would be to use a try block, like this:

set persistentID to "F1A68AD90AA66648"
tell application "iTunes"
    try
        set matchtrack to get first track in playlist 1 whose persistent ID is persistentID
        if matchtrack is not {} then
            log (get name of matchtrack)
        else
            log "no track found"
        end if
    on error the error_message number the error_number
        log "Error (probably no track found)"
        -- display dialog "Error: " & the error_number & ". " & the error_message buttons {"Cancel"} default button 1
    end try
end tell

BTW: use log instead of print and (get name of matchtrack) instead of (name of matchtrack)

This would work but goes thru all the tracks in a named playlist:

set flagFound to false
set mTrack to ""


# SETUP THOSE FIRST
# -------------------------------------------------------
property Library_Name : "Library" # "Mediathek" in german
property Playlist_Name : "Bob Marley"

set persistentID to "F1A68AD90AA66648"
# -------------------------------------------------------

tell application "iTunes"

    tell source Library_Name
        tell playlist Playlist_Name
            repeat with i from the (count of tracks) to 1 by -1

                if (the persistent ID of track i is persistentID) then
                    set mTrack to track i
                    set flagFound to true
                    exit repeat
                end if

            end repeat
        end tell
    end tell

    if flagFound then

        tell mTrack
            log "Found…"
            log "Name: " & (get name)
            log "persistent ID: " & (get persistent ID)
        end tell

    else

        log "no track with persistent ID " & persistentID & " found"

    end if

end tell