Search entities in the correct namespace

Instead of assuming that all entities are in namespace 0 (which is only
true in a Wikidata-like installation, but not in a default Wikibase
installation, and even then only for items, not properties), take the
actual namespace of the requested entity from an injected
EntityNamespaceLookup.

Also, if we can’t find the entity, throw an exception instead of
returning count 0: it’s better to fail the import than to duplicate
statements.

Fixes #22.

src/EntityImporterFactory.php

@@ -70,7 +70,7 @@ public function newEntityImporter() {
 				$this->getApiEntityLookup(),
 				$this->entityStore,
 				$this->getImportedEntityMappingStore(),
-				new PagePropsStatementCountLookup( $this->loadBalancer ),
+				new PagePropsStatementCountLookup( $this->loadBalancer, $this->getEntityNamespaceLookup() ),
 				$this->logger
 			);
 		}
@@ -127,6 +127,12 @@ private function newSerializerFactory() {
 			new DataValueSerializer()
 		);
 	}
+
+	private function getEntityNamespaceLookup() {
+		$wikibaseRepo = WikibaseRepo::getDefaultInstance();
+
+		return $wikibaseRepo->getEntityNamespaceLookup();
+	}
 }
 
 $maintClass = "Wikibase\Import\Maintenance\ImportEntities";

src/PagePropsStatementCountLookup.php

@@ -2,15 +2,21 @@
 
 namespace Wikibase\Import;
 
+use Exception;
 use LoadBalancer;
 use Wikibase\DataModel\Entity\EntityId;
+use Wikibase\Lib\Store\EntityNamespaceLookup;
+use Wikibase\Repo\WikibaseRepo;
 
 class PagePropsStatementCountLookup implements StatementsCountLookup {
 
 	private $loadBalancer;
 
-	public function __construct( LoadBalancer $loadBalancer ) {
+	private $lookup;
+
+	public function __construct( LoadBalancer $loadBalancer, EntityNamespaceLookup $lookup ) {
 		$this->loadBalancer = $loadBalancer;
+		$this->lookup = $lookup;
 	}
 
 	public function getStatementCount( EntityId $entityId ) {
@@ -20,7 +26,7 @@ public function getStatementCount( EntityId $entityId ) {
 			array( 'page_props', 'page' ),
 			array( 'pp_value' ),
 			array(
-				'page_namespace' => 0,
+				'page_namespace' => $this->lookup->getEntityNamespace( $entityId->getEntityType() ),
 				'page_title' => $entityId->getSerialization(),
 				'pp_propname' => 'wb-claims'
 			),
@@ -32,7 +38,7 @@ public function getStatementCount( EntityId $entityId ) {
 		$this->loadBalancer->closeConnection( $db );
 
 		if ( $res === false ) {
-			return 0;
+			throw new Exception( 'Could not find entity ' . $entityId->getSerialization() . ' in page_props!' );
 		}
 
 		return (int)$res->pp_value;