Support external hosted attachments via link.

src/Entity/Attachment.php

@@ -128,6 +128,34 @@ abstract class Attachment extends NamedDBElement
         return file_exists($this->getPath()) || static::isURL($this->getPath());
     }
 
+    /**
+     * The URL to the external file.
+     * Returns null, if the file is not external.
+     * @return string|null
+     */
+    public function getURL(): ?string
+    {
+        if (!$this->isExternal()) {
+            return null;
+        }
+
+        return $this->path;
+    }
+
+    /**
+     * Returns the hostname where the external file is stored.
+     * Returns null, if the file is not external.
+     * @return string|null
+     */
+    public function getHost(): ?string
+    {
+        if (!$this->isExternal()) {
+            return null;
+        }
+
+        return parse_url($this->getURL(), PHP_URL_HOST);
+    }
+
     /**
      * Get the filepath, relative to %BASE%.
      *
@@ -138,6 +166,8 @@ abstract class Attachment extends NamedDBElement
         return $this->path;
     }
 
+
+
     /**
      * Returns the filename of the attachment.
      * For a path like %BASE/path/foo.bar, foo.bar will be returned.

src/Services/EntityURLGenerator.php

@@ -95,6 +95,9 @@ class EntityURLGenerator
     public function viewURL($entity) : string
     {
         if ($entity instanceof Attachment) {
+            if ($entity->isExternal()) { //For external attachments, return the link to external path
+                return $entity->getURL();
+            }
             return $this->urlGenerator->generate('attachment_view', ['id' => $entity->getID()]);
         }
 
@@ -105,6 +108,9 @@ class EntityURLGenerator
     public function downloadURL($entity) : string
     {
         if ($entity instanceof Attachment) {
+            if ($entity->isExternal()) { //For external attachments, return the link to external path
+                return $entity->getURL();
+            }
             return $this->urlGenerator->generate('attachment_download', ['id' => $entity->getID()]);
         }