title: Genric null condition check for any datatype in python
body: <p>I am trying to check for any null column present using below logic but I am not sure will this work for other datatype, Is there is any other generic way to check null condition in python which will work for all datatypes.</p>
  <pre><code>from pyspark.sql import Row
  from pyspark.sql.types import *
  from pyspark.sql.functions import *
  df = sc.parallelize([ \
      Row(name='Alice', age=5, height=''), \
      Row(name='Kate', age=10, height=90), \
      Row(name='Brain', age=15, height=100)]).toDF()
  
  df.createOrReplaceTempView(&quot;Test&quot;)
  dfn1 = df.select([count(when(isnull(c), c)).alias(c) for c in df.columns])
  df10=dfn1.selectExpr(&quot;stack(3,'name',bigint(name),'age',bigint(age),'height',bigint(height)) as (col_name,null_col_check)&quot;).show()
  
  output : 
  
  +--------+--------+
  |col_name|null_col|
  +--------+--------+
  |    name|       0|
  |     age|       0|
  |  height|       1|
  +--------+--------+
  </code></pre>