From 5c0347e3874f883d95e1fea7475159527a3a0219 Mon Sep 17 00:00:00 2001
From: Jim Kalafut <jkalafut@hashicorp.com>
Date: Thu, 7 Jun 2018 21:45:22 -0700
Subject: [PATCH 1/2] service/dynamodb/dynamodbattribute: Retain backwards
 compatibility with ConvertTo data

---
 service/dynamodb/dynamodbattribute/decode.go  | 11 +++++++++
 .../dynamodb/dynamodbattribute/decode_test.go | 24 +++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/service/dynamodb/dynamodbattribute/decode.go b/service/dynamodb/dynamodbattribute/decode.go
index e02497568e9..f6cbbbc63d1 100644
--- a/service/dynamodb/dynamodbattribute/decode.go
+++ b/service/dynamodb/dynamodbattribute/decode.go
@@ -1,6 +1,7 @@
 package dynamodbattribute
 
 import (
+	"encoding/base64"
 	"fmt"
 	"reflect"
 	"strconv"
@@ -538,6 +539,16 @@ func (d *Decoder) decodeString(s *string, v reflect.Value, fieldTag tag) error {
 	switch v.Kind() {
 	case reflect.String:
 		v.SetString(*s)
+	case reflect.Slice:
+		// To maintain backwards compatibility with the ConvertFrom family of methods
+		// which converted []byte into base64-encoded strings if the input was typed
+		if v.Type() == byteSliceType {
+			decoded, err := base64.StdEncoding.DecodeString(*s)
+			if err != nil {
+				return &UnmarshalTypeError{Value: "string", Type: v.Type()}
+			}
+			v.SetBytes(decoded)
+		}
 	case reflect.Interface:
 		// Ensure type aliasing is handled properly
 		v.Set(reflect.ValueOf(*s).Convert(v.Type()))
diff --git a/service/dynamodb/dynamodbattribute/decode_test.go b/service/dynamodb/dynamodbattribute/decode_test.go
index 1313064af6f..0f73a68b07c 100644
--- a/service/dynamodb/dynamodbattribute/decode_test.go
+++ b/service/dynamodb/dynamodbattribute/decode_test.go
@@ -234,6 +234,30 @@ func TestUnmarshalListError(t *testing.T) {
 	}
 }
 
+func TestUnmarshalConvertToData(t *testing.T) {
+	type T struct {
+		Int       int
+		Str       string
+		ByteSlice []byte
+		StrSlice  []string
+	}
+
+	exp := T{
+		Int:       42,
+		Str:       "foo",
+		ByteSlice: []byte{42, 97, 83},
+		StrSlice:  []string{"cat", "dog"},
+	}
+	av, err := ConvertToMap(exp)
+	if err != nil {
+		t.Fatalf("expect no error, got %v", err)
+	}
+
+	var act T
+	err = UnmarshalMap(av, &act)
+	assertConvertTest(t, 0, act, exp, err, nil)
+}
+
 func TestUnmarshalMapShared(t *testing.T) {
 	for i, c := range sharedMapTestCases {
 		err := UnmarshalMap(c.in, c.actual)

From fcd5a4094bd9267d5328f925cb1490c172498d3f Mon Sep 17 00:00:00 2001
From: Jim Kalafut <jkalafut@hashicorp.com>
Date: Fri, 8 Jun 2018 13:06:14 -0700
Subject: [PATCH 2/2] Switch to UnmarshalError and update docs

---
 service/dynamodb/dynamodbattribute/decode.go | 2 +-
 service/dynamodb/dynamodbattribute/doc.go    | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/service/dynamodb/dynamodbattribute/decode.go b/service/dynamodb/dynamodbattribute/decode.go
index f6cbbbc63d1..41b67b3ae02 100644
--- a/service/dynamodb/dynamodbattribute/decode.go
+++ b/service/dynamodb/dynamodbattribute/decode.go
@@ -545,7 +545,7 @@ func (d *Decoder) decodeString(s *string, v reflect.Value, fieldTag tag) error {
 		if v.Type() == byteSliceType {
 			decoded, err := base64.StdEncoding.DecodeString(*s)
 			if err != nil {
-				return &UnmarshalTypeError{Value: "string", Type: v.Type()}
+				return &UnmarshalError{Err: err, Value: "string", Type: v.Type()}
 			}
 			v.SetBytes(decoded)
 		}
diff --git a/service/dynamodb/dynamodbattribute/doc.go b/service/dynamodb/dynamodbattribute/doc.go
index 7a51ac07616..b83a29c951f 100644
--- a/service/dynamodb/dynamodbattribute/doc.go
+++ b/service/dynamodb/dynamodbattribute/doc.go
@@ -81,7 +81,7 @@
 // The ConvertTo, ConvertToList, ConvertToMap, ConvertFrom, ConvertFromMap
 // and ConvertFromList methods have been deprecated. The Marshal and Unmarshal
 // functions should be used instead. The ConvertTo|From marshallers do not
-// support BinarySet, NumberSet, nor StringSets, and will incorrect marshal
+// support BinarySet, NumberSet, nor StringSets, and will incorrectly marshal
 // binary data fields in structs as base64 strings.
 //
 // The Marshal and Unmarshal functions correct this behavior, and removes
@@ -91,5 +91,11 @@
 // replaced with have been replaced with dynamodbattribute.Marshaler and
 // dynamodbattribute.Unmarshaler interfaces.
 //
+// The Unmarshal functions are backwards compatible with data marshalled by
+// ConvertTo*, but the reverse is not true: objects marshalled using Marshal
+// are not necessarily usable by ConvertFrom*. This backward compatibility is
+// intended to assist with incremental upgrading of data following a switch
+// away from the Convert* family of functions.
+//
 // `time.Time` is marshaled as RFC3339 format.
 package dynamodbattribute