[SPARK-3988][SQL] add public API for date type

Add json and python api for date type.
By using Pickle, `java.sql.Date` was serialized as calendar, and recognized in python as `datetime.datetime`.

Author: Daoyuan Wang <daoyuan.wang@intel.com>

Closes #2901 from adrian-wang/spark3988 and squashes the following commits:

c51a24d [Daoyuan Wang] convert datetime to date
5670626 [Daoyuan Wang] minor line combine
f760d8e [Daoyuan Wang] fix indent
444f100 [Daoyuan Wang] fix a typo
1d74448 [Daoyuan Wang] fix scala style
8d7dd22 [Daoyuan Wang] add json and python api for date type

3 files changed, 11 insertions, 3 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ScalaReflection.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ScalaReflection.scala
index 7d930fccd5..d76c743d3f 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ScalaReflection.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ScalaReflection.scala
@@ -112,6 +112,7 @@ object ScalaReflection {
     case obj: FloatType.JvmType => FloatType
     case obj: DoubleType.JvmType => DoubleType
     case obj: DecimalType.JvmType => DecimalType
+    case obj: DateType.JvmType => DateType
     case obj: TimestampType.JvmType => TimestampType
     case null => NullType
     // For other cases, there is no obvious mapping from the type of the given object to a
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/types/dataTypes.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/types/dataTypes.scala
index 0cf139ebde..b9cf37d53f 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/types/dataTypes.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/types/dataTypes.scala
@@ -91,6 +91,7 @@ object DataType {
       | "BinaryType" ^^^ BinaryType
       | "BooleanType" ^^^ BooleanType
       | "DecimalType" ^^^ DecimalType
+      | "DateType" ^^^ DateType
       | "TimestampType" ^^^ TimestampType
       )
 
@@ -198,7 +199,8 @@ trait PrimitiveType extends DataType {
 }
 
 object PrimitiveType {
-  private[sql] val all = Seq(DecimalType, TimestampType, BinaryType) ++ NativeType.all
+  private[sql] val all = Seq(DecimalType, DateType, TimestampType, BinaryType) ++
+    NativeType.all
 
   private[sql] val nameToType = all.map(t => t.typeName -> t).toMap
 }
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/ScalaReflectionSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/ScalaReflectionSuite.scala
index 488e373854..430f0664b7 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/ScalaReflectionSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/ScalaReflectionSuite.scala
@@ -18,7 +18,7 @@
 package org.apache.spark.sql.catalyst
 
 import java.math.BigInteger
-import java.sql.Timestamp
+import java.sql.{Date, Timestamp}
 
 import org.scalatest.FunSuite
 
@@ -43,6 +43,7 @@ case class NullableData(
     booleanField: java.lang.Boolean,
     stringField: String,
     decimalField: BigDecimal,
+    dateField: Date,
     timestampField: Timestamp,
     binaryField: Array[Byte])
 
@@ -96,6 +97,7 @@ class ScalaReflectionSuite extends FunSuite {
         StructField("booleanField", BooleanType, nullable = true),
         StructField("stringField", StringType, nullable = true),
         StructField("decimalField", DecimalType, nullable = true),
+        StructField("dateField", DateType, nullable = true),
         StructField("timestampField", TimestampType, nullable = true),
         StructField("binaryField", BinaryType, nullable = true))),
       nullable = true))
@@ -199,8 +201,11 @@ class ScalaReflectionSuite extends FunSuite {
     // DecimalType
     assert(DecimalType === typeOfObject(BigDecimal("1.7976931348623157E318")))
 
+    // DateType
+    assert(DateType === typeOfObject(Date.valueOf("2014-07-25")))
+
     // TimestampType
-    assert(TimestampType === typeOfObject(java.sql.Timestamp.valueOf("2014-07-25 10:26:00")))
+    assert(TimestampType === typeOfObject(Timestamp.valueOf("2014-07-25 10:26:00")))
 
     // NullType
     assert(NullType === typeOfObject(null))