title: Filtering Dataset in Spark with String Search
body: <p>I'm trying to just do a simple string filter with the dataset api using <code>startsWith</code> but I can't get the below statement to work. I can use <code>contains</code> like this. Not sure what I'm missing here. </p>
  
  <pre><code>  ds.filter(_.colToFilter.toString.contains("0")).show(false)
  </code></pre>
  
  <p>But this just produces an empty dataset but I know that the string is there in the value. </p>
  
  <pre><code>  ds.filter(_.colToFilter.toString.startsWith("0")).show(false)
  </code></pre>