Replace Spark SQL isNull check with Spark Scala based DSL (#493)

- This is to ensure columns with spaces in their names get their names escaped correctly in the where condition.
- Added a test to verify.

Author: rdsharma26

src/main/scala/com/amazon/deequ/analyzers/Analyzer.scala

@@ -465,20 +465,26 @@ private[deequ] object Analyzers {
     conditionalSelection(col(selection), where)
   }
 
-  def conditionalSelection(selection: Column, where: Option[String], replaceWith: Double): Column = {
-    val conditionColumn = where.map(expr)
-    conditionColumn
+  def conditionSelectionGivenColumn(selection: Column, where: Option[Column], replaceWith: Double): Column = {
+    where
       .map { condition => when(condition, replaceWith).otherwise(selection) }
       .getOrElse(selection)
   }
 
-  def conditionalSelection(selection: Column, where: Option[String], replaceWith: String): Column = {
-    val conditionColumn = where.map(expr)
-    conditionColumn
+  def conditionSelectionGivenColumn(selection: Column, where: Option[Column], replaceWith: String): Column = {
+    where
       .map { condition => when(condition, replaceWith).otherwise(selection) }
       .getOrElse(selection)
   }
 
+  def conditionalSelection(selection: Column, where: Option[String], replaceWith: Double): Column = {
+    conditionSelectionGivenColumn(selection, where.map(expr), replaceWith)
+  }
+
+  def conditionalSelection(selection: Column, where: Option[String], replaceWith: String): Column = {
+    conditionSelectionGivenColumn(selection, where.map(expr), replaceWith)
+  }
+
   def conditionalSelection(selection: Column, condition: Option[String]): Column = {
     val conditionColumn = condition.map { expression => expr(expression) }
     conditionalSelectionFromColumns(selection, conditionColumn)

src/main/scala/com/amazon/deequ/analyzers/MaxLength.scala

@@ -49,12 +49,13 @@ case class MaxLength(column: String, where: Option[String] = None, analyzerOptio
   override def filterCondition: Option[String] = where
 
   private def criterion(nullBehavior: NullBehavior): Column = {
+    val isNullCheck = col(column).isNull
     nullBehavior match {
       case NullBehavior.Fail =>
         val colLengths: Column = length(conditionalSelection(column, where)).cast(DoubleType)
-        conditionalSelection(colLengths, Option(s"${column} IS NULL"), replaceWith = Double.MaxValue)
+        conditionSelectionGivenColumn(colLengths, Option(isNullCheck), replaceWith = Double.MaxValue)
       case NullBehavior.EmptyString =>
-        length(conditionalSelection(col(column), Option(s"${column} IS NULL"), replaceWith = "")).cast(DoubleType)
+        length(conditionSelectionGivenColumn(col(column), Option(isNullCheck), replaceWith = "")).cast(DoubleType)
       case _ => length(conditionalSelection(column, where)).cast(DoubleType)
     }
   }

src/main/scala/com/amazon/deequ/analyzers/MinLength.scala

@@ -22,7 +22,9 @@ import com.amazon.deequ.analyzers.Preconditions.hasColumn
 import com.amazon.deequ.analyzers.Preconditions.isString
 import org.apache.spark.sql.Column
 import org.apache.spark.sql.Row
-import org.apache.spark.sql.functions.{col, length, min}
+import org.apache.spark.sql.functions.col
+import org.apache.spark.sql.functions.length
+import org.apache.spark.sql.functions.min
 import org.apache.spark.sql.types.DoubleType
 import org.apache.spark.sql.types.StructType
 
@@ -47,12 +49,13 @@ case class MinLength(column: String, where: Option[String] = None, analyzerOptio
   override def filterCondition: Option[String] = where
 
   private[deequ] def criterion(nullBehavior: NullBehavior): Column = {
+    val isNullCheck = col(column).isNull
     nullBehavior match {
       case NullBehavior.Fail =>
         val colLengths: Column = length(conditionalSelection(column, where)).cast(DoubleType)
-        conditionalSelection(colLengths, Option(s"${column} IS NULL"), replaceWith = Double.MinValue)
+        conditionSelectionGivenColumn(colLengths, Option(isNullCheck), replaceWith = Double.MinValue)
       case NullBehavior.EmptyString =>
-        length(conditionalSelection(col(column), Option(s"${column} IS NULL"), replaceWith = "")).cast(DoubleType)
+        length(conditionSelectionGivenColumn(col(column), Option(isNullCheck), replaceWith = "")).cast(DoubleType)
       case _ => length(conditionalSelection(column, where)).cast(DoubleType)
     }
   }

src/test/scala/com/amazon/deequ/profiles/ColumnProfilerTest.scala

@@ -78,6 +78,27 @@ class ColumnProfilerTest extends WordSpec with Matchers with SparkContextSpec
       assert(actualColumnProfile == expectedColumnProfile)
     }
 
+    "return correct StringColumnProfile for column names with spaces" in withSparkSession { session =>
+      val data = getDfCompleteAndInCompleteColumnsWithSpacesInNames(session)
+      val columnNames = data.columns.toSeq
+
+      val lengthMap = Map(
+        "att 1" -> (1, 3),
+        "att 2" -> (0, 7)
+      )
+
+      lengthMap.foreach { case (columnName, (minLength, maxLength)) =>
+        val actualColumnProfile = ColumnProfiler.profile(data, Option(columnNames), false, 1)
+          .profiles(columnName)
+
+        assert(actualColumnProfile.isInstanceOf[StringColumnProfile])
+        val actualStringColumnProfile = actualColumnProfile.asInstanceOf[StringColumnProfile]
+
+        assert(actualStringColumnProfile.minLength.contains(minLength))
+        assert(actualStringColumnProfile.maxLength.contains(maxLength))
+      }
+    }
+
     "return correct columnProfiles with predefined dataType" in withSparkSession { session =>
 
       val data = getDfCompleteAndInCompleteColumns(session)
@@ -131,7 +152,6 @@ class ColumnProfilerTest extends WordSpec with Matchers with SparkContextSpec
       assert(actualColumnProfile == expectedColumnProfile)
     }
 
-
     "return correct NumericColumnProfiles for numeric String DataType columns" in
       withSparkSession { session =>
 
@@ -171,6 +191,7 @@ class ColumnProfilerTest extends WordSpec with Matchers with SparkContextSpec
         assertProfilesEqual(expectedColumnProfile,
           actualColumnProfile.asInstanceOf[NumericColumnProfile])
     }
+
     "return correct NumericColumnProfiles for numeric String DataType columns when " +
       "kllProfiling disabled" in withSparkSession { session =>
 
@@ -562,7 +583,6 @@ class ColumnProfilerTest extends WordSpec with Matchers with SparkContextSpec
     )
 
     assertSameColumnProfiles(columnProfiles.profiles, expectedProfiles)
-
   }
 
   private[this] def assertSameColumnProfiles(

src/test/scala/com/amazon/deequ/utils/FixtureSupport.scala

@@ -159,6 +159,19 @@ trait FixtureSupport {
     ).toDF("item", "att1", "att2")
   }
 
+  def getDfCompleteAndInCompleteColumnsWithSpacesInNames(sparkSession: SparkSession): DataFrame = {
+    import sparkSession.implicits._
+
+    Seq(
+      ("1", "ab", "abc1"),
+      ("2", "bc", null),
+      ("3", "ab", "def2ghi"),
+      ("4", "ab", null),
+      ("5", "bcd", "ab"),
+      ("6", "a", "pqrs")
+    ).toDF("some item", "att 1", "att 2")
+  }
+
   def getDfCompleteAndInCompleteColumnsAndVarLengthStrings(sparkSession: SparkSession): DataFrame = {
     import sparkSession.implicits._