diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/CSVOptions.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/CSVOptions.scala index a13a5a34b4a84..29e76875ad9a1 100644 --- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/CSVOptions.scala +++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/CSVOptions.scala @@ -152,7 +152,11 @@ class CSVOptions( writerSettings.setIgnoreLeadingWhitespaces(ignoreLeadingWhiteSpaceFlagInWrite) writerSettings.setIgnoreTrailingWhitespaces(ignoreTrailingWhiteSpaceFlagInWrite) writerSettings.setNullValue(nullValue) - writerSettings.setEmptyValue(nullValue) + // The Univocity parser parses empty strings as `null` by default. This is the default behavior + // for Spark too, since `nullValue` defaults to an empty string and has a higher precedence to + // setEmptyValue(). But when `nullValue` is set to a different value, that would mean that the + // empty string should be parsed not as `null` but as an empty string. + writerSettings.setEmptyValue("") writerSettings.setSkipEmptyLines(true) writerSettings.setQuoteAllFields(quoteAll) writerSettings.setQuoteEscapingEnabled(escapeQuotes) diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala index 4fe45420b4e77..140ac9b52e640 100644 --- a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala +++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala @@ -1248,4 +1248,50 @@ class CSVSuite extends QueryTest with SharedSQLContext with SQLTestUtils { Row("0,2013-111-11 12:13:14") :: Row(null) :: Nil ) } + + test("SPARK-17916: An empty string should not be coerced to null when nullValue is passed.") { + val litNull: String = null + val df = Seq( + (1, "John Doe"), + (2, ""), + (3, "-"), + (4, litNull) + ).toDF("id", "name") + + // Checks for new behavior where an empty string is not coerced to null when `nullValue` is + // set to anything but an empty string literal. + withTempPath { path => + df.write + .option("nullValue", "-") + .csv(path.getAbsolutePath) + val computed = spark.read + .option("nullValue", "-") + .schema(df.schema) + .csv(path.getAbsolutePath) + val expected = Seq( + (1, "John Doe"), + (2, ""), + (3, litNull), + (4, litNull) + ).toDF("id", "name") + + checkAnswer(computed, expected) + } + // Keeps the old behavior where empty string us coerced to nullValue is not passed. + withTempPath { path => + df.write + .csv(path.getAbsolutePath) + val computed = spark.read + .schema(df.schema) + .csv(path.getAbsolutePath) + val expected = Seq( + (1, "John Doe"), + (2, litNull), + (3, "-"), + (4, litNull) + ).toDF("id", "name") + + checkAnswer(computed, expected) + } + } }