Page: Avoid 1000+ queries for projects dropdown menu

Before, we re-used ProjectsAction, which in turn re-uses JobAction, which
in turn queries several hundred results (for the last job of each
project) to termine the status color of the "Last job" column
on the "/projects" page. However, none of that is used by the dropdown
menu.

Replace it with a single DB query. Still re-used, to avoid code
duplication, but no longer re-using the rest of that action class.

inc/Page.php

@@ -226,8 +226,7 @@ public function output() {
 		if ( $this->exceptionObj === null ) {
 			try {
 				$projectsAction = ProjectsAction::newFromContext( $context );
-				$projectsAction->doAction();
-				$projects = $projectsAction->getData();
+				$projects = $projectsAction->getProjectRows();
 
 			} catch ( Exception $e ) {
 				$pageObj = Error500Page::newFromContext( $context );
@@ -297,7 +296,7 @@ public function output() {
 							<li class="nav-header">Projects</li>
 <?php
 foreach ( $projects as $project ) {
-	echo $this->getPageLink( "project/{$project['id']}", $project['displayTitle'] );
+	echo $this->getPageLink( "project/{$project->id}", $project->display_title );
 }
 ?>
 						</ul>

inc/actions/ProjectsAction.php

@@ -31,39 +31,8 @@ public function doAction() {
 			return;
 		}
 
-		$sortDirQuery = '';
-		switch ( $sortDir ) {
-			case 'asc':
-				$sortDirQuery = 'ASC';
-				break;
-			case 'desc':
-				$sortDirQuery = 'DESC';
-				break;
-		}
-
-		$sortFieldQuery = '';
-		switch ( $sortField ) {
-			case 'title':
-				$sortFieldQuery = "ORDER BY display_title $sortDirQuery";
-				break;
-			case 'id':
-				$sortFieldQuery = "ORDER BY id $sortDirQuery";
-				break;
-			case 'creation':
-				$sortFieldQuery = "ORDER BY created $sortDirQuery";
-				break;
-		}
-
 		$projects = array();
-		$projectRows = $db->getRows(
-			"SELECT
-				id,
-				display_title,
-				created
-			FROM projects
-			$sortFieldQuery;"
-		);
-
+		$projectRows = $this->getProjectRows( $sortField, $sortDir );
 		if ( $projectRows ) {
 			foreach ( $projectRows as $projectRow ) {
 				// Get information about the latest job (if any)
@@ -95,4 +64,41 @@ public function doAction() {
 
 		$this->setData( $projects );
 	}
+
+	/**
+	 * @param string|null $sortField
+	 * @param string|null $sortDir
+	 * @return stdClass[]
+	 */
+	public function getProjectRows( $sortField = null, $sortDir = null ) {
+		$db = $this->getContext()->getDB();
+
+		switch ( $sortDir ) {
+			case 'desc':
+				$sortDirQuery = 'DESC';
+				break;
+			default:
+				$sortDirQuery = 'ASC';
+		}
+
+		switch ( $sortField ) {
+			case 'id':
+				$sortFieldQuery = "ORDER BY id $sortDirQuery";
+				break;
+			case 'creation':
+				$sortFieldQuery = "ORDER BY created $sortDirQuery";
+				break;
+			default:
+				$sortFieldQuery = "ORDER BY display_title $sortDirQuery";
+		}
+
+		return $db->getRows(
+			"SELECT
+				id,
+				display_title,
+				created
+			FROM projects
+			$sortFieldQuery;"
+		);
+	}
 }