Allowing to refer to external links from a modeladmin

code/GridFieldExternalLink.php

@@ -0,0 +1,67 @@
+<?php
+/**
+ * Displays a link to an external source referenced 'external link'
+ */
+class GridFieldExternalLink extends GridFieldDataColumns {
+
+	/**
+	 * Add a column for the actions
+	 *
+	 * @param type $gridField
+	 * @param array $columns
+	 */
+	public function augmentColumns($gridField, &$columns) {
+		if(!in_array('Actions', $columns)) $columns[] = 'Actions';
+	}
+
+	/**
+	 * Return any special attributes that will be used for FormField::create_tag()
+	 *
+	 * @param GridField $gridField
+	 * @param DataObject $record
+	 * @param string $columnName
+	 * @return array
+	 */
+	public function getColumnAttributes($gridField, $record, $columnName) {
+		return array('class' => 'col-buttons');
+	}
+
+	/**
+	 * Add the title
+	 *
+	 * @param GridField $gridField
+	 * @param string $columnName
+	 * @return array
+	 */
+	public function getColumnMetadata($gridField, $columnName) {
+		if($columnName == 'Actions') {
+			return array('title' => '');
+		}
+		return array();
+	}
+
+	/**
+	 * Which columns are handled by this component
+	 *
+	 * @param type $gridField
+	 * @return type
+	 */
+	public function getColumnsHandled($gridField) {
+		return array('Actions');
+	}
+
+	/**
+	 * @param GridField $gridField
+	 * @param DataObject $record
+	 * @param string $columnName
+	 *
+	 * @return string - the HTML for the column
+	 */
+	public function getColumnContent($gridField, $record, $columnName) {
+		$data = new ArrayData(array(
+			'Link' => method_exists($record, 'getExternalLink') ? $record->getExternalLink() : $record->ExternalLink
+		));
+
+		return $data->renderWith('GridFieldExternalLink');
+	}
+}

templates/GridFieldExternalLink.ss

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+<a href="$Link" target="_blank" title="<% _t('GridFieldExtensions.ExternalLink','External Link') %>"><% _t('GridFieldExtensions.ExternalLink','External Link') %></a>