Minor refactoring and add partitionBy to save, saveAsTable, and parquet.

python/pyspark/sql/readwriter.py

@@ -218,7 +218,10 @@ def mode(self, saveMode):
 
         >>> df.write.mode('append').parquet(os.path.join(tempfile.mkdtemp(), 'data'))
         """
-        self._jwrite = self._jwrite.mode(saveMode)
+        # At the JVM side, the default value of mode is already set to "error".
+        # So, if the given saveMode is None, we will not call JVM-side's mode method.
+        if saveMode is not None:
+            self._jwrite = self._jwrite.mode(saveMode)
         return self
 
     @since(1.4)
@@ -253,11 +256,12 @@ def partitionBy(self, *cols):
         """
         if len(cols) == 1 and isinstance(cols[0], (list, tuple)):
             cols = cols[0]
-        self._jwrite = self._jwrite.partitionBy(_to_seq(self._sqlContext._sc, cols))
+        if len(cols) > 0:
+            self._jwrite = self._jwrite.partitionBy(_to_seq(self._sqlContext._sc, cols))
         return self
 
     @since(1.4)
-    def save(self, path=None, format=None, mode=None, **options):
+    def save(self, path=None, format=None, mode=None, partitionBy=(), **options):
         """Saves the contents of the :class:`DataFrame` to a data source.
 
         The data source is specified by the ``format`` and a set of ``options``.
@@ -276,11 +280,7 @@ def save(self, path=None, format=None, mode=None, **options):
 
         >>> df.write.mode('append').parquet(os.path.join(tempfile.mkdtemp(), 'data'))
         """
-        if mode is not None:
-            # At the JVM side, the default value of mode is already set to "error".
-            # We will only call mode method if the provided mode is not None.
-            self.mode(mode)
-        self.options(**options)
+        self.partitionBy(partitionBy).mode(mode).options(**options)
         if format is not None:
             self.format(format)
         if path is None:
@@ -300,7 +300,7 @@ def insertInto(self, tableName, overwrite=False):
         self._jwrite.mode("overwrite" if overwrite else "append").insertInto(tableName)
 
     @since(1.4)
-    def saveAsTable(self, name, format=None, mode=None, **options):
+    def saveAsTable(self, name, format=None, mode=None, partitionBy=(), **options):
         """Saves the content of the :class:`DataFrame` as the specified table.
 
         In the case the table already exists, behavior of this function depends on the
@@ -318,11 +318,7 @@ def saveAsTable(self, name, format=None, mode=None, **options):
         :param mode: one of `append`, `overwrite`, `error`, `ignore` (default: error)
         :param options: all other string options
         """
-        if mode is not None:
-            # At the JVM side, the default value of mode is already set to "error".
-            # We will only call mode method if the provided mode is not None.
-            self.mode(mode)
-        self.options(**options)
+        self.partitionBy(partitionBy).mode(mode).options(**options)
         if format is not None:
             self.format(format)
         self._jwrite.saveAsTable(name)
@@ -341,14 +337,10 @@ def json(self, path, mode=None):
 
         >>> df.write.json(os.path.join(tempfile.mkdtemp(), 'data'))
         """
-        if mode is not None:
-            # At the JVM side, the default value of mode is already set to "error".
-            # We will only call mode method if the provided mode is not None.
-            self.mode(mode)
-        self._jwrite.json(path)
+        self._jwrite.mode(mode).json(path)
 
     @since(1.4)
-    def parquet(self, path, mode=None):
+    def parquet(self, path, mode=None, partitionBy=()):
         """Saves the content of the :class:`DataFrame` in Parquet format at the specified path.
 
         :param path: the path in any Hadoop supported file system
@@ -361,10 +353,7 @@ def parquet(self, path, mode=None):
 
         >>> df.write.parquet(os.path.join(tempfile.mkdtemp(), 'data'))
         """
-        if mode is not None:
-            # At the JVM side, the default value of mode is already set to "error".
-            # We will only call mode method if the provided mode is not None.
-            self.mode(mode)
+        self.partitionBy(partitionBy).mode(mode)
         self._jwrite.parquet(path)
 
     @since(1.4)
@@ -386,14 +375,10 @@ def jdbc(self, url, table, mode=None, properties={}):
                            arbitrary string tag/value. Normally at least a
                            "user" and "password" property should be included.
         """
-        if mode is not None:
-            # At the JVM side, the default value of mode is already set to "error".
-            # We will only call mode method if the provided mode is not None.
-            self.mode(mode)
         jprop = JavaClass("java.util.Properties", self._sqlContext._sc._gateway._gateway_client)()
         for k in properties:
             jprop.setProperty(k, properties[k])
-        self._jwrite.jdbc(url, table, jprop)
+        self._jwrite.mode(mode).jdbc(url, table, jprop)
 
 
 def _test():