PHPLIB-219: Fix BSON serialization of findAndModify write concern

src/Operation/FindAndModify.php

@@ -191,7 +191,7 @@ class FindAndModify implements Executable
         }
 
         if (isset($this->options['writeConcern']) && \MongoDB\server_supports_feature($server, self::$wireVersionForWriteConcern)) {
-            $cmd['writeConcern'] = $this->options['writeConcern'];
+            $cmd['writeConcern'] = \MongoDB\write_concern_as_document($this->options['writeConcern']);
         }
 
         return new Command($cmd);

src/functions.php

@@ -5,6 +5,7 @@ namespace MongoDB;
 use MongoDB\BSON\Serializable;
 use MongoDB\Driver\ReadConcern;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\WriteConcern;
 use MongoDB\Exception\InvalidArgumentException;
 use stdClass;
 
@@ -140,3 +141,30 @@ function server_supports_feature(Server $server, $feature)
 
     return ($minWireVersion <= $feature && $maxWireVersion >= $feature);
 }
+
+/**
+ * Converts a WriteConcern instance to a stdClass for use in a BSON document.
+ *
+ * @internal
+ * @see https://jira.mongodb.org/browse/PHPC-498
+ * @param WriteConcern $writeConcern Write concern
+ * @return stdClass
+ */
+function write_concern_as_document(WriteConcern $writeConcern)
+{
+    $document = [];
+
+    if ($writeConcern->getW() !== null) {
+        $document['w'] = $writeConcern->getW();
+    }
+
+    if ($writeConcern->getJournal() !== null) {
+        $document['j'] = $writeConcern->getJournal();
+    }
+
+    if ($writeConcern->getWtimeout() !== 0) {
+        $document['wtimeout'] = $writeConcern->getWtimeout();
+    }
+
+    return (object) $document;
+}

tests/FunctionsTest.php

@@ -3,6 +3,7 @@
 namespace MongoDB\Tests;
 
 use MongoDB\Driver\ReadConcern;
+use MongoDB\Driver\WriteConcern;
 
 /**
  * Unit tests for utility functions.
@@ -25,4 +26,32 @@ class FunctionsTest extends \PHPUnit_Framework_TestCase
             [ new ReadConcern(ReadConcern::MAJORITY), (object) ['level' => ReadConcern::MAJORITY] ],
         ];
     }
+
+    /**
+     * @dataProvider provideWriteConcernsAndDocuments
+     */
+    public function testWriteConcernAsDocument(WriteConcern $writeConcern, $expectedDocument)
+    {
+        $this->assertEquals($expectedDocument, \MongoDB\write_concern_as_document($writeConcern));
+    }
+
+    public function provideWriteConcernsAndDocuments()
+    {
+        return [
+            [ new WriteConcern(-3), (object) ['w' => 'majority'] ], // MONGOC_WRITE_CONCERN_W_MAJORITY
+            [ new WriteConcern(-2), (object) [] ], // MONGOC_WRITE_CONCERN_W_DEFAULT
+            [ new WriteConcern(-1), (object) ['w' => -1] ],
+            [ new WriteConcern(0), (object) ['w' => 0] ],
+            [ new WriteConcern(1), (object) ['w' => 1] ],
+            [ new WriteConcern('majority'), (object) ['w' => 'majority'] ],
+            [ new WriteConcern('tag'), (object) ['w' => 'tag'] ],
+            [ new WriteConcern(1, 0), (object) ['w' => 1] ],
+            [ new WriteConcern(1, 0, false), (object) ['w' => 1, 'j' => false] ],
+            [ new WriteConcern(1, 1000), (object) ['w' => 1, 'wtimeout' => 1000] ],
+            [ new WriteConcern(1, 1000, true), (object) ['w' => 1, 'wtimeout' => 1000, 'j' => true] ],
+            [ new WriteConcern(-2, 0, true), (object) ['j' => true] ],
+            // Note: wtimeout is only applicable applies for w > 1
+            [ new WriteConcern(-2, 1000), (object) ['wtimeout' => 1000] ],
+        ];
+    }
 }