diff --git a/google/cloud/automl_v1beta1/tables/tables_client.py b/google/cloud/automl_v1beta1/tables/tables_client.py
index 32137db2..378eca61 100644
--- a/google/cloud/automl_v1beta1/tables/tables_client.py
+++ b/google/cloud/automl_v1beta1/tables/tables_client.py
@@ -18,11 +18,12 @@
 
 import pkg_resources
 import logging
+import six
 
 from google.api_core.gapic_v1 import client_info
 from google.api_core import exceptions
 from google.cloud.automl_v1beta1 import gapic
-from google.cloud.automl_v1beta1.proto import data_types_pb2, data_items_pb2
+from google.cloud.automl_v1beta1.proto import data_items_pb2
 from google.cloud.automl_v1beta1.tables import gcs_client
 from google.protobuf import struct_pb2
 
@@ -31,6 +32,61 @@
 _LOGGER = logging.getLogger(__name__)
 
 
+def to_proto_value(value):
+    """translates a Python value to a google.protobuf.Value.
+
+  Args:
+  value: The Python value to be translated.
+
+  Returns:
+  Tuple of the translated google.protobuf.Value and error if any.
+  """
+    # possible Python types (this is a Python3 module):
+    # https://simplejson.readthedocs.io/en/latest/#encoders-and-decoders
+    #   JSON              Python 2        Python 3
+    # object              dict            dict
+    # array               list            list
+    # string              unicode         str
+    # number (int)        int, long       int
+    # number (real)       float           float
+    # true                True            True
+    # false               False           False
+    # null                None            None
+    if value is None:
+        # translate null to an empty value.
+        return struct_pb2.Value(null_value=struct_pb2.NullValue.NULL_VALUE), None
+    elif isinstance(value, bool):
+        # This check needs to happen before isinstance(value, int),
+        # isinstance(value, int) returns True when value is bool.
+        return struct_pb2.Value(bool_value=value), None
+    elif isinstance(value, six.integer_types) or isinstance(value, float):
+        return struct_pb2.Value(number_value=value), None
+    elif isinstance(value, six.string_types) or isinstance(value, six.text_type):
+        return struct_pb2.Value(string_value=value), None
+    elif isinstance(value, dict):
+        struct_value = struct_pb2.Struct()
+        for key, v in value.items():
+            field_value, err = to_proto_value(v)
+            if err is not None:
+                return None, err
+
+            struct_value.fields[key].CopyFrom(field_value)
+        return struct_pb2.Value(struct_value=struct_value), None
+    elif isinstance(value, list):
+        list_value = []
+        for v in value:
+            proto_value, err = to_proto_value(v)
+            if err is not None:
+                return None, err
+            list_value.append(proto_value)
+        return (
+            struct_pb2.Value(list_value=struct_pb2.ListValue(values=list_value)),
+            None,
+        )
+    else:
+        return None, "unsupport data type: {}".format(type(value))
+
+
 class TablesClient(object):
     """
     AutoML Tables API helper.
@@ -404,42 +460,6 @@ def __column_spec_name_from_args(
 
         return column_spec_name
 
-    def __data_type_to_proto_value(self, data_type, value):
-        type_code = data_type.type_code
-        if value is None:
-            return struct_pb2.Value(null_value=struct_pb2.NullValue.NULL_VALUE)
-        elif type_code == data_types_pb2.FLOAT64:
-            return struct_pb2.Value(number_value=value)
-        elif (
-            type_code == data_types_pb2.TIMESTAMP
-            or type_code == data_types_pb2.STRING
-            or type_code == data_types_pb2.CATEGORY
-        ):
-            return struct_pb2.Value(string_value=value)
-        elif type_code == data_types_pb2.ARRAY:
-            if isinstance(value, struct_pb2.ListValue):
-                # in case the user passed in a ListValue.
-                return struct_pb2.Value(list_value=value)
-            array = []
-            for item in value:
-                array.append(
-                    self.__data_type_to_proto_value(data_type.list_element_type, item)
-                )
-            return struct_pb2.Value(list_value=struct_pb2.ListValue(values=array))
-        elif type_code == data_types_pb2.STRUCT:
-            if isinstance(value, struct_pb2.Struct):
-                # in case the user passed in a Struct.
-                return struct_pb2.Value(struct_value=value)
-            struct_value = struct_pb2.Struct()
-            for k, v in value.items():
-                field_value = self.__data_type_to_proto_value(
-                    data_type.struct_type.fields[k], v
-                )
-                struct_value.fields[k].CopyFrom(field_value)
-            return struct_pb2.Value(struct_value=struct_value)
-        else:
-            raise ValueError("Unknown type_code: {}".format(type_code))
-
     def __ensure_gcs_client_is_initialized(self, credentials, project):
         """Checks if GCS client is initialized. Initializes it if not.
 
@@ -2714,7 +2734,9 @@ def predict(
 
         values = []
         for i, c in zip(inputs, column_specs):
-            value_type = self.__data_type_to_proto_value(c.data_type, i)
+            value_type, err = to_proto_value(i)
+            if err is not None:
+                raise ValueError(err)
             values.append(value_type)
 
         row = data_items_pb2.Row(values=values)