[SPARK-9114] [SQL] [PySpark] convert returned object from UDF into internal type

This PR also remove the duplicated code between registerFunction and UserDefinedFunction.

cc JoshRosen

Author: Davies Liu <davies@databricks.com>

Closes #7450 from davies/fix_return_type and squashes the following commits:

e80bf9f [Davies Liu] remove debugging code
f94b1f6 [Davies Liu] fix mima
8f9c58b [Davies Liu] convert returned object from UDF into internal type

3 files changed, 14 insertions, 21 deletions

diff --git a/python/pyspark/sql/context.py b/python/pyspark/sql/context.py
index c93a15bada..abb6522dde 100644
--- a/python/pyspark/sql/context.py
+++ b/python/pyspark/sql/context.py
@@ -34,6 +34,7 @@ from pyspark.sql.types import Row, StringType, StructType, _verify_type, \
 from pyspark.sql.dataframe import DataFrame
 from pyspark.sql.readwriter import DataFrameReader
 from pyspark.sql.utils import install_exception_handler
+from pyspark.sql.functions import UserDefinedFunction
 
 try:
     import pandas
@@ -191,19 +192,8 @@ class SQLContext(object):
         >>> sqlContext.sql("SELECT stringLengthInt('test')").collect()
         [Row(_c0=4)]
         """
-        func = lambda _, it: map(lambda x: f(*x), it)
-        ser = AutoBatchedSerializer(PickleSerializer())
-        command = (func, None, ser, ser)
-        pickled_cmd, bvars, env, includes = _prepare_for_python_RDD(self._sc, command, self)
-        self._ssql_ctx.udf().registerPython(name,
-                                            bytearray(pickled_cmd),
-                                            env,
-                                            includes,
-                                            self._sc.pythonExec,
-                                            self._sc.pythonVer,
-                                            bvars,
-                                            self._sc._javaAccumulator,
-                                            returnType.json())
+        udf = UserDefinedFunction(f, returnType, name)
+        self._ssql_ctx.udf().registerPython(name, udf._judf)
 
     def _inferSchemaFromList(self, data):
         """
diff --git a/python/pyspark/sql/functions.py b/python/pyspark/sql/functions.py
index fd5a3ba8ad..031745a1c4 100644
--- a/python/pyspark/sql/functions.py
+++ b/python/pyspark/sql/functions.py
@@ -801,23 +801,24 @@ class UserDefinedFunction(object):
 
     .. versionadded:: 1.3
     """
-    def __init__(self, func, returnType):
+    def __init__(self, func, returnType, name=None):
         self.func = func
         self.returnType = returnType
         self._broadcast = None
-        self._judf = self._create_judf()
+        self._judf = self._create_judf(name)
 
-    def _create_judf(self):
-        f = self.func  # put it in closure `func`
-        func = lambda _, it: map(lambda x: f(*x), it)
+    def _create_judf(self, name):
+        f, returnType = self.func, self.returnType  # put them in closure `func`
+        func = lambda _, it: map(lambda x: returnType.toInternal(f(*x)), it)
         ser = AutoBatchedSerializer(PickleSerializer())
         command = (func, None, ser, ser)
         sc = SparkContext._active_spark_context
         pickled_command, broadcast_vars, env, includes = _prepare_for_python_RDD(sc, command, self)
         ssql_ctx = sc._jvm.SQLContext(sc._jsc.sc())
         jdt = ssql_ctx.parseDataType(self.returnType.json())
-        fname = f.__name__ if hasattr(f, '__name__') else f.__class__.__name__
-        judf = sc._jvm.UserDefinedPythonFunction(fname, bytearray(pickled_command), env, includes,
+        if name is None:
+            name = f.__name__ if hasattr(f, '__name__') else f.__class__.__name__
+        judf = sc._jvm.UserDefinedPythonFunction(name, bytearray(pickled_command), env, includes,
                                                  sc.pythonExec, sc.pythonVer, broadcast_vars,
                                                  sc._javaAccumulator, jdt)
         return judf
diff --git a/python/pyspark/sql/tests.py b/python/pyspark/sql/tests.py
index 7a55d801e4..ea821f486f 100644
--- a/python/pyspark/sql/tests.py
+++ b/python/pyspark/sql/tests.py
@@ -417,12 +417,14 @@ class SQLTests(ReusedPySparkTestCase):
         self.assertEquals(point, ExamplePoint(1.0, 2.0))
 
     def test_udf_with_udt(self):
-        from pyspark.sql.tests import ExamplePoint
+        from pyspark.sql.tests import ExamplePoint, ExamplePointUDT
         row = Row(label=1.0, point=ExamplePoint(1.0, 2.0))
         df = self.sc.parallelize([row]).toDF()
         self.assertEqual(1.0, df.map(lambda r: r.point.x).first())
         udf = UserDefinedFunction(lambda p: p.y, DoubleType())
         self.assertEqual(2.0, df.select(udf(df.point)).first()[0])
+        udf2 = UserDefinedFunction(lambda p: ExamplePoint(p.x + 1, p.y + 1), ExamplePointUDT())
+        self.assertEqual(ExamplePoint(2.0, 3.0), df.select(udf2(df.point)).first()[0])
 
     def test_parquet_with_udt(self):
         from pyspark.sql.tests import ExamplePoint