ENHANCEMENT GridFieldExportButton allows an anon function to return the

value of a related object. Useful for handling has_many/many_many data
in a single CSV column.

forms/gridfield/GridFieldExportButton.php

@@ -6,9 +6,6 @@
 
 /**
  * Adds an "Export list" button to the bottom of a GridField.
- * 
- * WARNING: This is experimental and its API is subject to change.  Feel free to use it as long as you are happy of
- * refactoring your code in the future.
  */
 class GridFieldExportButton implements GridField_HTMLProvider, GridField_ActionProvider, GridField_URLHandler {
 
@@ -95,7 +92,10 @@ class GridFieldExportButton implements GridField_HTMLProvider, GridField_ActionP
 	}
 
 	/**
-	 * Export core.
+	 * Generate export fields for CSV.
+	 *
+	 * @param GridField $gridField
+	 * @return array
 	 */
 	function generateExportFileData($gridField) {
 		$separator = $this->csvSeparator;
@@ -105,20 +105,42 @@ class GridFieldExportButton implements GridField_HTMLProvider, GridField_ActionP
 		$fieldItems = new ArrayList();
 
 		if($this->csvHasHeader) {
-			$fileData .= "\"" . implode("\"{$separator}\"", array_values($csvColumns)) . "\"";
+			$headers = array();
+
+			// determine the CSV headers. If a field is callable (e.g. anonymous function) then use the
+			// source name as the header instead
+			foreach($csvColumns as $columnSource => $columnHeader) {
+				$headers[] = (!is_string($columnHeader) && is_callable($columnHeader)) ? $columnSource : $columnHeader;
+			}
+
+			$fileData .= "\"" . implode("\"{$separator}\"", array_values($headers)) . "\"";
 			$fileData .= "\n";
 		}
 
 		$items = $gridField->getList();
+
+		// @todo should GridFieldComponents change behaviour based on whether others are available in the config?
 		foreach($gridField->getConfig()->getComponents() as $component){
 			if($component instanceof GridFieldFilterHeader || $component instanceof GridFieldSortableHeader) {
 				$items = $component->getManipulatedData($gridField, $items);
 			}
 		}
+
 		foreach($items as $item) {
 			$columnData = array();
 			foreach($csvColumns as $columnSource => $columnHeader) {
+				if(!is_string($columnHeader) && is_callable($columnHeader)) {
+					if($item->hasMethod($columnSource)) {
+						$relObj = $item->{$columnSource}();
+					} else {
+						$relObj = $item->relObject($columnSource);
+					}
+
+					$value = $columnHeader($relObj);
+				} else {
 					$value = $item->relField($columnSource);
+				}
+
 				$value = str_replace(array("\r", "\n"), "\n", $value);
 				$columnData[] = '"' . str_replace('"', '\"', $value) . '"';
 			}

forms/gridfield/GridFieldPrintButton.php

@@ -6,9 +6,6 @@
 
 /**
  * Adds an "Print" button to the bottom or top of a GridField.
- * 
- * WARNING: This is experimental and its API is subject to change.  Feel free to use it as long as you are happy of
- * refactoring your code in the future.
  */
 class GridFieldPrintButton implements GridField_HTMLProvider, GridField_ActionProvider, GridField_URLHandler {
 

tests/forms/gridfield/GridFieldExportButtonTest.php

@@ -0,0 +1,89 @@
+<?php
+class GridFieldExportButtonTest extends SapphireTest {
+
+	protected $list;
+
+	protected $gridField;
+
+	protected $form;
+
+	public static $fixture_file = 'GridFieldExportButtonTest.yml';
+
+	protected $extraDataObjects = array(
+		'GridFieldExportButtonTest_Team'
+	);
+
+	public function setUp() {
+		parent::setUp();
+
+		$this->list = new DataList('GridFieldExportButtonTest_Team');
+		$config = GridFieldConfig::create()->addComponent(new GridFieldExportButton());
+		$this->gridField = new GridField('testfield', 'testfield', $this->list, $config);
+	}
+
+	public function testGenerateFileDataBasicFields() {
+		$button = new GridFieldExportButton();
+		$button->setExportColumns(array('Name' => 'My Name'));
+
+		$this->assertEquals(
+			"\"My Name\"\n\"Test\"\n\"Test2\"\n",
+			$button->generateExportFileData($this->gridField)
+		);
+	}
+
+	public function testGenerateFileDataAnonymousFunctionField() {
+		$button = new GridFieldExportButton();
+		$button->setExportColumns(array(
+			'Name' => 'Name',
+			'City' => function($obj) {
+				return $obj->getValue() . ' city';
+			}
+		));
+
+		$this->assertEquals(
+			"\"Name\",\"City\"\n\"Test\",\"City city\"\n\"Test2\",\"City2 city\"\n",
+			$button->generateExportFileData($this->gridField)
+		);
+	}
+
+	public function testBuiltInFunctionNameCanBeUsedAsHeader() {
+		$button = new GridFieldExportButton();
+		$button->setExportColumns(array(
+			'Name' => 'Name',
+			'City' => 'strtolower'
+		));
+
+		$this->assertEquals(
+			"\"Name\",\"strtolower\"\n\"Test\",\"City\"\n\"Test2\",\"City2\"\n",
+			$button->generateExportFileData($this->gridField)
+		);
+	}
+
+	public function testNoCsvHeaders() {
+		$button = new GridFieldExportButton();
+		$button->setExportColumns(array(
+			'Name' => 'Name',
+			'City' => 'City'
+		));
+		$button->setCsvHasHeader(false);
+
+		$this->assertEquals(
+			"\"Test\",\"City\"\n\"Test2\",\"City2\"\n",
+			$button->generateExportFileData($this->gridField)
+		);
+	}
+
+}
+class GridFieldExportButtonTest_Team extends DataObject implements TestOnly {
+
+	static $db = array(
+		'Name' => 'Varchar',
+		'City' => 'Varchar'
+	);
+
+	public function canView($member = null) {
+		return true;
+	}
+
+}
+

tests/forms/gridfield/GridFieldExportButtonTest.yml

@@ -0,0 +1,8 @@
+GridFieldExportButtonTest_Team:
+    test-team-1:
+        Name: Test
+        City: City
+    test-team-2:
+        Name: Test2
+        City: City2
+