Optional field that allows users to force PDF downloads, otherwise allow browsers to open in new tab

README.md

@@ -90,6 +90,15 @@ Note: Both operations copy the existing file.
 	$docs = $dms->getByTag('priority', 'important')->First();
 	$link = $doc->getLink();
 
+	// Set default download behavior ('open' or 'download'). 'download' is the system default
+	// Attempt to open the file in the browser
+	Config::inst()->update('DMSDocument', 'default_download_behaviour', 'open');
+	
+Or in you config.yml:
+
+    DMSDocument:
+      default_download_behaviour: open
+
 #### Manage Page Relations
 
 	// Find documents by page

_config.php

@@ -1,7 +1,6 @@
 <?php
 
 $config = Config::inst();
-$config->update('DMSDocument_versions', 'enable_versions', true);
 
 DMSSiteTreeExtension::show_documents_tab(); //show the Documents tab on all pages
 DMSSiteTreeExtension::no_documents_tab();   //and don't exclude it from any pages
@@ -21,4 +20,3 @@ if ($config->get('DMSDocument_versions', 'enable_versions')) {
 	//using the same db relations for the versioned documents, as for the actual documents
 	$config->update('DMSDocument_versions', 'db', $config->get('DMSDocument', 'db'));
 }
-

_config/dmsdocument.yml

@@ -11,3 +11,5 @@ SiteTree:
 HtmlEditorField_Toolbar:
   extensions:
     - DocumentHtmlEditorFieldToolbar
+DMSDocument_versions:
+  enable_versions: true

code/model/DMSDocument.php

@@ -17,7 +17,8 @@ class DMSDocument extends DataObject implements DMSDocumentInterface
         "EmbargoedIndefinitely" => 'Boolean(false)',
         "EmbargoedUntilPublished" => 'Boolean(false)',
         "EmbargoedUntilDate" => 'SS_DateTime',
-        "ExpireAtDate" => 'SS_DateTime'
+        "ExpireAtDate" => 'SS_DateTime',
+        "DownloadBehavior" => 'Enum(array("open","download"), "download")',
     );
 
     private static $many_many = array(
@@ -52,6 +53,12 @@ class DMSDocument extends DataObject implements DMSDocumentInterface
         'LastChanged'
     );
 
+    /**
+     * @var string download|open
+     * @config
+     */
+    private static $default_download_behaviour = 'download';
+
     /**
      * @param Member $member
      *
@@ -147,7 +154,6 @@ class DMSDocument extends DataObject implements DMSDocumentInterface
 
 
 
-
     /**
      * Associates this document with a Page. This method does nothing if the
      * association already exists.
@@ -902,7 +908,6 @@ class DMSDocument extends DataObject implements DMSDocumentInterface
         $fields = new FieldList();  //don't use the automatic scaffolding, it is slow and unnecessary here
 
         $extraTasks = '';   //additional text to inject into the list of tasks at the bottom of a DMSDocument CMSfield
-        $extraFields = FormField::create('Empty');
 
         //get list of shortcode page relations
         $relationFinder = new ShortCodeRelationFinder();
@@ -914,6 +919,28 @@ class DMSDocument extends DataObject implements DMSDocumentInterface
         $fields->add(new TextField('Title', 'Title'));
         $fields->add(new TextareaField('Description', 'Description'));
 
+        $downloadBehaviorSource = array(
+            'open' => _t('DMSDocument.OPENINBROWSER', 'Open in browser'),
+            'download' => _t('DMSDocument.FORCEDOWNLOAD', 'Force download'),
+        );
+        $defaultDownloadBehaviour = Config::inst()->get('DMSDocument', 'default_download_behaviour');
+        if (!isset($downloadBehaviorSource[$defaultDownloadBehaviour])) {
+            user_error('Default download behaviour "' . $defaultDownloadBehaviour . '" not supported.', E_USER_WARNING);
+        }
+        else {
+            $downloadBehaviorSource[$defaultDownloadBehaviour] .= ' (' . _t('DMSDocument.DEFAULT', 'default') . ')';
+        }
+
+        $fields->add(
+            OptionsetField::create(
+                'DownloadBehavior',
+                _t('DMSDocument.DOWNLOADBEHAVIOUR', 'Download behavior'),
+                $downloadBehaviorSource,
+                $defaultDownloadBehaviour
+            )
+            ->setDescription('How the visitor will view this file. <strong>Open in browser</strong> allows files to be opened in a new tab.')
+        );
+
         //create upload field to replace document
         $uploadField = new DMSUploadField('ReplaceFile', 'Replace file');
         $uploadField->setConfig('allowedMaxFileNumber', 1);
@@ -1341,6 +1368,14 @@ class DMSDocument_Controller extends Controller
                         return $path;
                     }
 
+                    // set fallback if no config nor file-specific value
+                    $disposition = 'attachment';
+
+                    // file-specific setting
+                    if ($doc->DownloadBehavior == 'open') {
+                        $disposition = 'inline';
+                    }
+
                     //if a DMSDocument can be downloaded and all the permissions/privileges has passed,
                     //its ViewCount should be increased by 1 just before the browser sending the file to front.
                     $doc->trackView();
@@ -1348,7 +1383,7 @@ class DMSDocument_Controller extends Controller
                     header('Content-Type: ' . $mime);
                     header('Content-Length: ' . filesize($path), null);
                     if (!empty($mime) && $mime != "text/html") {
-                        header('Content-Disposition: attachment; filename="'.$doc->getFilenameWithoutID().'"');
+                        header('Content-Disposition: '.$disposition.'; filename="'.$doc->getFilenameWithoutID().'"');
                     }
                     header('Content-transfer-encoding: 8bit');
                     header('Expires: 0');