Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like CMSPageHistoryController often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use CMSPageHistoryController, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 7 | class CMSPageHistoryController extends CMSMain { | 
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| 8 | |||
| 9 | private static $url_segment = 'pages/history';  | 
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| 10 | private static $url_rule = '/$Action/$ID/$VersionID/$OtherVersionID';  | 
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| 11 | private static $url_priority = 42;  | 
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| 12 | private static $menu_title = 'History';  | 
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| 13 | private static $required_permission_codes = 'CMS_ACCESS_CMSMain';  | 
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| 14 | private static $session_namespace = 'CMSMain';  | 
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| 15 | |||
| 16 | private static $allowed_actions = array(  | 
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| 17 | 'VersionsForm',  | 
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| 18 | 'CompareVersionsForm',  | 
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| 19 | 'show',  | 
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| 20 | 'compare'  | 
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| 21 | );  | 
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| 22 | |||
| 23 | private static $url_handlers = array(  | 
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| 24 | '$Action/$ID/$VersionID/$OtherVersionID' => 'handleAction'  | 
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| 25 | );  | 
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| 26 | |||
| 27 | 	public function getResponseNegotiator() { | 
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| 40 | |||
| 41 | /**  | 
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| 42 | * @param SS_HTTPRequest $request  | 
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| 43 | * @return array  | 
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| 44 | */  | 
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| 45 | View Code Duplication | 	public function show($request) { | 
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| 59 | |||
| 60 | /**  | 
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| 61 | * @param SS_HTTPRequest $request  | 
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| 62 | * @return array  | 
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| 63 | */  | 
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| 64 | View Code Duplication | 	public function compare($request) { | 
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| 81 | |||
| 82 | 	public function getSilverStripeNavigator() { | 
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| 91 | |||
| 92 | /**  | 
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| 93 | 	 * Returns the read only version of the edit form. Detaches all {@link FormAction} | 
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| 94 | * instances attached since only action relates to revert.  | 
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| 95 | *  | 
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| 96 | 	 * Permission checking is done at the {@link CMSMain::getEditForm()} level. | 
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| 97 | *  | 
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| 98 | * @param int $id ID of the record to show  | 
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| 99 | * @param array $fields optional  | 
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| 100 | * @param int $versionID  | 
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| 101 | * @param int $compareID Compare mode  | 
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| 102 | *  | 
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| 103 | * @return Form  | 
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| 104 | */  | 
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| 105 | 	public function getEditForm($id = null, $fields = null, $versionID = null, $compareID = null) { | 
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| 106 | if(!$id) $id = $this->currentPageID();  | 
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| 107 | |||
| 108 | $record = $this->getRecord($id, $versionID);  | 
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| 109 | $versionID = ($record) ? $record->Version : $versionID;  | 
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| 110 | |||
| 111 | $form = parent::getEditForm($record, ($record) ? $record->getCMSFields() : null);  | 
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| 112 | // Respect permission failures from parent implementation  | 
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| 113 | if(!($form instanceof Form)) return $form;  | 
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| 114 | |||
| 115 | // TODO: move to the SilverStripeNavigator structure so the new preview can pick it up.  | 
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| 116 | //$nav = new SilverStripeNavigatorItem_ArchiveLink($record);  | 
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| 117 | |||
| 118 | $form->setActions(new FieldList(  | 
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| 119 | 			$revert = FormAction::create('doRollback', _t('CMSPageHistoryController.REVERTTOTHISVERSION', 'Revert to this version'))->setUseButtonTag(true) | 
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| 120 | ));  | 
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| 121 | |||
| 122 | $fields = $form->Fields();  | 
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| 123 | 		$fields->removeByName("Status"); | 
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| 124 | 		$fields->push(new HiddenField("ID")); | 
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| 125 | 		$fields->push(new HiddenField("Version")); | 
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| 126 | |||
| 127 | $fields = $fields->makeReadonly();  | 
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| 128 | |||
| 129 | 		if($compareID) { | 
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| 130 | $link = Controller::join_links(  | 
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| 131 | 				$this->Link('show'), | 
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| 132 | $id  | 
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| 133 | );  | 
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| 134 | |||
| 135 | 			$view = _t('CMSPageHistoryController.VIEW',"view"); | 
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| 136 | |||
| 137 | $message = _t(  | 
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| 138 | 'CMSPageHistoryController.COMPARINGVERSION',  | 
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| 139 | 				"Comparing versions {version1} and {version2}.", | 
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| 140 | array(  | 
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| 141 | 					'version1' => sprintf('%s (<a href="%s">%s</a>)', $versionID, Controller::join_links($link, $versionID), $view), | 
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| 142 | 					'version2' => sprintf('%s (<a href="%s">%s</a>)', $compareID, Controller::join_links($link, $compareID), $view) | 
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| 143 | )  | 
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| 144 | );  | 
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| 145 | |||
| 146 | $revert->setReadonly(true);  | 
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| 147 | 		} else { | 
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| 148 | 			if($record->isLatestVersion()) { | 
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| 149 | 				$message = _t('CMSPageHistoryController.VIEWINGLATEST', 'Currently viewing the latest version.'); | 
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| 150 | 			} else { | 
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| 151 | $message = _t(  | 
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| 152 | 'CMSPageHistoryController.VIEWINGVERSION',  | 
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| 153 | 					"Currently viewing version {version}.", | 
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| 154 | 					array('version' => $versionID) | 
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| 155 | );  | 
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| 156 | }  | 
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| 157 | }  | 
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| 158 | |||
| 159 | 		$fields->addFieldToTab('Root.Main', | 
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| 160 | 			new LiteralField('CurrentlyViewingMessage', $this->customise(array( | 
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| 161 | 'Content' => $message,  | 
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| 162 | 'Classes' => 'notice'  | 
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| 163 | 			))->renderWith(array('CMSMain_notice'))), | 
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| 164 | "Title"  | 
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| 165 | );  | 
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| 166 | |||
| 167 | $form->setFields($fields->makeReadonly());  | 
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| 168 | $form->loadDataFrom(array(  | 
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| 169 | "ID" => $id,  | 
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| 170 | "Version" => $versionID,  | 
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| 171 | ));  | 
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| 172 | |||
| 173 | 		if(($record && $record->isLatestVersion())) { | 
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| 174 | $revert->setReadonly(true);  | 
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| 175 | }  | 
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| 176 | |||
| 177 | 		$form->removeExtraClass('cms-content'); | 
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| 178 | |||
| 179 | return $form;  | 
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| 180 | }  | 
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| 181 | |||
| 182 | |||
| 183 | /**  | 
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| 184 | * Version select form. Main interface between selecting versions to view  | 
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| 185 | * and comparing multiple versions.  | 
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| 186 | *  | 
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| 187 | * Because we can reload the page directly to a compare view (history/compare/1/2/3)  | 
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| 188 | * this form has to adapt to those parameters as well.  | 
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| 189 | *  | 
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| 190 | * @return Form  | 
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| 191 | */  | 
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| 192 | 	public function VersionsForm() { | 
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| 193 | $id = $this->currentPageID();  | 
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| 194 | $page = $this->getRecord($id);  | 
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| 195 | $versionsHtml = '';  | 
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| 196 | |||
| 197 | 		$action = $this->getRequest()->param('Action'); | 
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| 198 | 		$versionID = $this->getRequest()->param('VersionID'); | 
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| 199 | 		$otherVersionID = $this->getRequest()->param('OtherVersionID'); | 
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| 200 | |||
| 201 | $showUnpublishedChecked = 0;  | 
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| 202 | $compareModeChecked = ($action == "compare");  | 
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| 203 | |||
| 204 | 		if($page) { | 
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| 205 | $versions = $page->allVersions();  | 
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| 206 | $versionID = (!$versionID) ? $page->Version : $versionID;  | 
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| 207 | |||
| 208 | 			if($versions) { | 
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| 209 | 				foreach($versions as $k => $version) { | 
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| 210 | $active = false;  | 
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| 211 | |||
| 212 | 					if($version->Version == $versionID || $version->Version == $otherVersionID) { | 
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| 213 | $active = true;  | 
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| 214 | |||
| 215 | if(!$version->WasPublished) $showUnpublishedChecked = 1;  | 
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| 216 | }  | 
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| 217 | |||
| 218 | $version->Active = ($active);  | 
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| 219 | }  | 
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| 220 | }  | 
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| 221 | |||
| 222 | $vd = new ViewableData();  | 
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| 223 | |||
| 224 | $versionsHtml = $vd->customise(array(  | 
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| 225 | 'Versions' => $versions  | 
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| 226 | 			))->renderWith('CMSPageHistoryController_versions'); | 
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| 227 | }  | 
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| 228 | |||
| 229 | $fields = new FieldList(  | 
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| 230 | new CheckboxField(  | 
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| 231 | 'ShowUnpublished',  | 
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| 232 | 				_t('CMSPageHistoryController.SHOWUNPUBLISHED','Show unpublished versions'), | 
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| 233 | $showUnpublishedChecked  | 
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| 234 | ),  | 
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| 235 | new CheckboxField(  | 
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| 236 | 'CompareMode',  | 
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| 237 | 				_t('CMSPageHistoryController.COMPAREMODE', 'Compare mode (select two)'), | 
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| 238 | $compareModeChecked  | 
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| 239 | ),  | 
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| 240 | 			new LiteralField('VersionsHtml', $versionsHtml), | 
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| 241 | 			$hiddenID = new HiddenField('ID', false, "") | 
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| 242 | );  | 
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| 243 | |||
| 244 | $actions = new FieldList(  | 
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| 245 | new FormAction(  | 
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| 246 | 				'doCompare', _t('CMSPageHistoryController.COMPAREVERSIONS','Compare Versions') | 
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| 247 | ),  | 
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| 248 | new FormAction(  | 
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| 249 | 				'doShowVersion', _t('CMSPageHistoryController.SHOWVERSION','Show Version') | 
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| 250 | )  | 
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| 251 | );  | 
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| 252 | |||
| 253 | // Use <button> to allow full jQuery UI styling  | 
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| 254 | foreach($actions->dataFields() as $action) $action->setUseButtonTag(true);  | 
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| 255 | |||
| 256 | $negotiator = $this->getResponseNegotiator();  | 
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| 257 | $form = Form::create(  | 
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| 258 | $this,  | 
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| 259 | 'VersionsForm',  | 
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| 260 | $fields,  | 
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| 261 | $actions  | 
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| 262 | 		)->setHTMLID('Form_VersionsForm'); | 
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| 263 | $form->loadDataFrom($this->getRequest()->requestVars());  | 
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| 264 | $hiddenID->setValue($id);  | 
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| 265 | $form->unsetValidator();  | 
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| 266 | |||
| 267 | $form  | 
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| 268 | 			->addExtraClass('cms-versions-form') // placeholder, necessary for $.metadata() to work | 
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| 269 | 			->setAttribute('data-link-tmpl-compare', Controller::join_links($this->Link('compare'), '%s', '%s', '%s')) | 
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| 270 | 			->setAttribute('data-link-tmpl-show', Controller::join_links($this->Link('show'), '%s', '%s')); | 
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| 271 | |||
| 272 | return $form;  | 
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| 273 | }  | 
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| 274 | |||
| 275 | /**  | 
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| 276 | 	 * Process the {@link VersionsForm} compare function between two pages. | 
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| 277 | *  | 
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| 278 | * @param array  | 
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| 279 | * @param Form  | 
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| 280 | *  | 
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| 281 | * @return html  | 
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| 282 | */  | 
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| 283 | 	public function doCompare($data, $form) { | 
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| 284 | $versions = $data['Versions'];  | 
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| 285 | if(count($versions) < 2) return null;  | 
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| 286 | |||
| 287 | $id = $this->currentPageID();  | 
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| 288 | $version1 = array_shift($versions);  | 
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| 289 | $version2 = array_shift($versions);  | 
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| 290 | |||
| 291 | $form = $this->CompareVersionsForm($version1, $version2);  | 
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| 292 | |||
| 293 | // javascript solution, render into template  | 
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| 294 | View Code Duplication | 		if($this->getRequest()->isAjax()) { | 
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| 295 | return $this->customise(array(  | 
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| 296 | "EditForm" => $form  | 
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| 297 | ))->renderWith(array(  | 
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| 298 | $this->class . '_EditForm',  | 
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| 299 | 'LeftAndMain_Content'  | 
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| 300 | ));  | 
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| 301 | }  | 
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| 302 | |||
| 303 | // non javascript, redirect the user to the page  | 
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| 304 | $this->redirect(Controller::join_links(  | 
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| 305 | 			$this->Link('compare'), | 
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| 306 | $version1,  | 
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| 307 | $version2  | 
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| 308 | ));  | 
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| 309 | }  | 
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| 310 | |||
| 311 | /**  | 
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| 312 | 	 * Process the {@link VersionsForm} show version function. Only requires | 
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| 313 | * one page to be selected.  | 
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| 314 | *  | 
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| 315 | * @param array  | 
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| 316 | * @param Form  | 
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| 317 | *  | 
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| 318 | * @return html  | 
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| 319 | */  | 
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| 320 | 	public function doShowVersion($data, $form) { | 
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| 321 | $versionID = null;  | 
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| 322 | |||
| 323 | 		if(isset($data['Versions']) && is_array($data['Versions'])) { | 
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| 324 | $versionID = array_shift($data['Versions']);  | 
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| 325 | }  | 
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| 326 | |||
| 327 | if(!$versionID) return;  | 
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| 328 | |||
| 329 | View Code Duplication | 		if($request->isAjax()) { | 
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| 330 | return $this->customise(array(  | 
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| 331 | "EditForm" => $this->ShowVersionForm($versionID)  | 
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| 332 | ))->renderWith(array(  | 
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| 333 | $this->class . '_EditForm',  | 
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| 334 | 'LeftAndMain_Content'  | 
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| 335 | ));  | 
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| 336 | }  | 
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| 337 | |||
| 338 | // non javascript, redirect the user to the page  | 
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| 339 | $this->redirect(Controller::join_links(  | 
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| 340 | 			$this->Link('version'), | 
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| 341 | $versionID  | 
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| 342 | ));  | 
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| 343 | }  | 
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| 344 | |||
| 345 | /**  | 
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| 346 | * @param int|null $versionID  | 
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| 347 | * @return Form  | 
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| 348 | */  | 
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| 349 | 	public function ShowVersionForm($versionID = null) { | 
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| 357 | |||
| 358 | /**  | 
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| 359 | * @param int $versionID  | 
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| 360 | * @param int $otherVersionID  | 
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| 361 | * @return Form  | 
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| 362 | */  | 
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| 363 | 	public function CompareVersionsForm($versionID, $otherVersionID) { | 
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| 364 | 		if($versionID > $otherVersionID) { | 
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| 365 | $toVersion = $versionID;  | 
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| 366 | $fromVersion = $otherVersionID;  | 
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| 367 | 		} else { | 
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| 368 | $toVersion = $otherVersionID;  | 
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| 369 | $fromVersion = $versionID;  | 
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| 370 | }  | 
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| 371 | |||
| 372 | if(!$toVersion || !$fromVersion) return false;  | 
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| 373 | |||
| 374 | $id = $this->currentPageID();  | 
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| 375 | 		$page = DataObject::get_by_id("SiteTree", $id); | 
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| 376 | |||
| 377 | 		if($page && !$page->canView()) { | 
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| 378 | return Security::permissionFailure($this);  | 
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| 379 | }  | 
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| 380 | |||
| 381 | $record = $page->compareVersions($fromVersion, $toVersion);  | 
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| 382 | |||
| 383 | 		$fromVersionRecord = Versioned::get_version('SiteTree', $id, $fromVersion); | 
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| 384 | 		$toVersionRecord = Versioned::get_version('SiteTree', $id, $toVersion); | 
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| 385 | |||
| 386 | 		if(!$fromVersionRecord) { | 
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| 387 | 			user_error("Can't find version $fromVersion of page $id", E_USER_ERROR); | 
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| 388 | }  | 
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| 389 | |||
| 390 | 		if(!$toVersionRecord) { | 
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| 391 | 			user_error("Can't find version $toVersion of page $id", E_USER_ERROR); | 
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| 392 | }  | 
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| 393 | |||
| 394 | 		if($record) { | 
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| 395 | $form = $this->getEditForm($id, null, null, true);  | 
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| 396 | $form->setActions(new FieldList());  | 
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| 397 | 			$form->addExtraClass('compare'); | 
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| 398 | |||
| 399 | // Comparison views shouldn't be editable.  | 
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| 400 | // Its important to convert fields *before* loading data,  | 
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| 401 | // as the comparison output is HTML and not valid values for the various field types  | 
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| 402 | $readonlyFields = $form->Fields()->makeReadonly();  | 
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| 403 | $form->setFields($readonlyFields);  | 
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| 404 | |||
| 405 | $form->loadDataFrom($record);  | 
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| 406 | $form->loadDataFrom(array(  | 
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| 407 | "ID" => $id,  | 
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| 408 | "Version" => $fromVersion,  | 
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| 409 | ));  | 
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| 410 | |||
| 411 | 			foreach($form->Fields()->dataFields() as $field) { | 
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| 412 | $field->dontEscape = true;  | 
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| 413 | }  | 
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| 414 | |||
| 415 | return $form;  | 
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| 416 | }  | 
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| 417 | }  | 
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| 418 | |||
| 419 | 	public function Breadcrumbs($unlinked = false) { | 
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| 424 | |||
| 425 | }  | 
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| 426 |