protocols/horizon: Display memo_bytes even when memo text is an empty string

protocols/horizon/main.go

@@ -488,14 +488,20 @@ type InnerTransaction struct {
 func (t Transaction) MarshalJSON() ([]byte, error) {
 	type Alias Transaction
 	v := &struct {
-		Memo *string `json:"memo,omitempty"`
+		Memo      *string `json:"memo,omitempty"`
+		MemoBytes *string `json:"memo_bytes,omitempty"`
 		*Alias
 	}{
 		Alias: (*Alias)(&t),
 	}
 	if t.MemoType != "none" {
 		v.Memo = &t.Memo
 	}
+
+	if t.MemoType == "text" {
+		v.MemoBytes = &t.MemoBytes
+	}
+
 	return json.Marshal(v)
 }
 

protocols/horizon/main_test.go

@@ -67,16 +67,19 @@ func TestTransactionJSONMarshal(t *testing.T) {
 
 func TestTransactionEmptyMemoText(t *testing.T) {
 	transaction := Transaction{
-		MemoType: "text",
-		Memo:     "",
+		MemoType:  "text",
+		Memo:      "",
+		MemoBytes: "",
 	}
 	marshaledTransaction, marshalErr := json.Marshal(transaction)
 	assert.Nil(t, marshalErr)
 	var result struct {
-		Memo *string
+		Memo      *string
+		MemoBytes *string `json:"memo_bytes"`
 	}
 	json.Unmarshal(marshaledTransaction, &result)
 	assert.NotNil(t, result.Memo, "memo field is present even if input memo was empty string")
+	assert.NotNil(t, result.MemoBytes, "memo_bytes field is present even if input memo was empty string")
 }
 
 func TestTransactionMemoTypeNone(t *testing.T) {

services/horizon/CHANGELOG.md

@@ -10,7 +10,7 @@ file. This project adheres to [Semantic Versioning](http://semver.org/).
 However, XDR strings are actually binary blobs with no enforced encoding. 
 It is possible to set the memo in a transaction envelope to a binary sequence which is not valid ASCII or unicode. 
 Previously, if you wanted to recover the original binary sequence for a transaction memo, you would have to decode the transaction's envelope.
-In this release, we have added a `memo_bytes` field to the Horizon transaction response.
+In this release, we have added a `memo_bytes` field to the Horizon transaction response for transactions with `memo_type` equal `text`.
 `memo_bytes` stores the base 64 encoding of the memo bytes set in the transaction envelope.