title: How to read bigQuery from PCollection in Dataflow
body: <p>I Have a PCollection of Object that I get from pubsub, let say :   </p>
  
  <pre><code> PCollection&lt;Student&gt; pStudent ;
  </code></pre>
  
  <p>and in student attributes, there is an attribute let say studentID;
  and I want to read attributes (class_code) from BigQuery with this student id and set the class_code that I get from BQ to student Object in PCollcetion </p>
  
  <p>is there anyone know how to implement this?
  I know that in beam there is a <strong><code>BigQueryIO</code></strong> but how can I do that, if the query string criteria that I want to execute in BQ is from student object (studentID) in PCollection and How can I set the value to PCollection from the result of BigQuery?</p>