a weird error while post request to server for store object

[HQS^??^]

dear everyone:
        I follow the tutorial at 
http://docs.basho.com/riak/kv/2.1.4/developing/usage/document-store/   , Step 
by Step Practice  , when I've Post a request for store object , but the riak 
server respond 400 (Bad Request)  ,  I review my code again and again , but  no 
problem found                     . see below:

<?php


class BlogPost {
 var  $_title = '';
 var  $_author = '';
 var  $_content = '';
 var  $_keywords = [];
 var  $_datePosted = '';
 var  $_published = false;
 var  $_bucketType = "cms";
 var  $_bucket = null;
 var  $_riak = null;
 var  $_location = null;
  public function __construct(Riak $riak, $bucket, $title, $author, $content, 
array $keywords, $date, $published)
  {
    $this->_riak = $riak;
    $this->_bucket = new Bucket($bucket, "cms");
    $this->_location = new Riak\Location('blog1',$this->_bucket,"cms");
    $this->_title = $title;
    $this->_author = $author;
    $this->_content = $content;
    $this->_keywords = $keywords;
    $this->_datePosted = $date;
    $this->_published = $published;
  }

  public function store()
  {
    $setBuilder = (new UpdateSet($this->_riak));
      
    foreach($this->_keywords as $keyword) {
      $setBuilder->add($keyword);
    }
/*
   (new UpdateMap($this->_riak))
      ->updateRegister('title', $this->_title)
      ->updateRegister('author', $this->_author)
      ->updateRegister('content', $this->_content)
      ->updateRegister('date', $this->_datePosted)
      ->updateFlag('published', $this->_published)
      ->updateSet('keywords', $setBuilder)
      ->withBucket($this->_bucket)
      ->build()
      ->execute();

*/
   $response = (new UpdateMap($this->_riak))
      ->updateRegister('title', $this->_title)
      ->updateRegister('author', $this->_author)
      ->updateRegister('content', $this->_content)
      ->updateRegister('date', $this->_datePosted)
      ->updateFlag('published', $this->_published)
      ->updateSet('keywords', $setBuilder)
      ->atLocation($this->_location)
      ->build()
      ->execute();

    echo '</br>';
      var_dump($response);
        echo '</br>';
  }
}

 $node = (new Node\Builder)
    ->atHost('192.168.111.2')
    ->onPort(8098)
    ->build();

    $riak = new Riak([$node]);


$keywords = ['adorbs', 'cheshire'];
$date = new \DateTime('now');


$post1 = new BlogPost(
  $riak,
  'cat_pics', // bucket
  'This one is so lulz!', // title
  'Cat Stevens', // author
  'Please check out these cat pics!', // content
  $keywords, // keywords
  $date, // date posted
  true // published
);
$post1->store();

the wireshark captured packet : 

 192.168.171.124(client ip)  =>  192.168.111.2(riak server ip)    HTTP    511   
 POST /types/cms/buckets/cat_pics/datatypes/alldoc? HTTP/1.1  (application/json)
 192.168.111.2    192.168.171.124    HTTP    251    HTTP/1.1 400 Bad Request 

 GET http://192.168.111.2:8098//types/cms/buckets/cat_pics/props
{"props":{"name":"cat_pics","young_vclock":20,"w":"quorum","small_vclock":50,"search_index":"blog_posts","rw":"quorum","r":"quorum","pw":0,"precommit":[],"pr":0,"postcommit":[],"old_vclock":86400,"notfound_ok":true,"n_val":3,"linkfun":{"mod":"riak_kv_wm_link_walker","fun":"mapreduce_linkfun"},"last_write_wins":false,"dw":"quorum","dvv_enabled":true,"chash_keyfun":{"mod":"riak_core_util","fun":"chash_std_keyfun"},"big_vclock":50,"basic_quorum":false,"allow_mult":true,"datatype":"map","active":true,"claimant":"node1@192.168.111.1"}}

       please help me catch the bugs  thanks in advance! 

regards
                                                                                
                                                                           Alan
_______________________________________________
riak-users mailing list
riak-users@lists.basho.com
http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com