CakePHP无法返回数组中的值（soapUi）

Question

我在像这样的cakephp中有一些功能

/** 
    * Get one record 
    * @param string $type
    * @return string[]
    */ 
    function readType($type = NULL) 
    { 
        $arr[] = array(
           "bookTitle" => "ThaiBook",
           "bookYear"  => 2007,
           "bookAuthor"=> "Oke"
         );
        $arr[] = array(
           "bookTitle" => "EnglishBook",
           "bookYear"  => 2001,
           "bookAuthor"=> "Eko"
         );

         return $arr;
    }

并且soapui不能像这样返回数组中的值

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="http://schema.example.com" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <SOAP-ENV:Body>
      <ns1:readTypeResponse>
         <readTypeReturn>
            ***<xsd:string>Array</xsd:string>
            <xsd:string>Array</xsd:string>***
         </readTypeReturn>
      </ns1:readTypeResponse>
   </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

我的问题在哪里？以及如何解决这个问题 谢谢你:)）