Added MarshalJSON to Vin and changed Vout.ScriptPubKey

Added MarshalJSON method to Vin which properly omits the Vout field
from coinbase Vin's by using anonymous structs with the proper
subsets of fields outputted by bitcoind

Changed Vout.ScriptPubKey to add omitempty for ReqSigs and Addresses:
both fields are not shown when there is an error identifying to
scriptType or parsing addresses in bitcoind

jsonapi.go

@@ -99,13 +99,43 @@ type ScriptSig struct {
 // Vin models parts of the tx data.  It is defined seperately since both
 // getrawtransaction and decoderawtransaction use the same structure.
 type Vin struct {
-	Coinbase  string     `json:"coinbase,omitempty"`
-	Txid      string     `json:"txid,omitempty"`
-	Vout      int        `json:"vout,omitempty"`
-	ScriptSig *ScriptSig `json:"scriptSig,omitempty"`
+	Coinbase  string     `json:"coinbase"`
+	Txid      string     `json:"txid"`
+	Vout      int        `json:"vout"`
+	ScriptSig *ScriptSig `json:"scriptSig"`
 	Sequence  uint32     `json:"sequence"`
 }
 
+func (v *Vin) IsCoinBase() bool {
+	return len(v.Coinbase) > 0
+}
+
+func (v *Vin) MarshalJSON() ([]byte, error) {
+	if v.IsCoinBase() {
+		coinbaseStruct := struct {
+			Coinbase string `json:"coinbase"`
+			Sequence uint32 `json:"sequence"`
+		}{
+			Coinbase: v.Coinbase,
+			Sequence: v.Sequence,
+		}
+		return json.Marshal(coinbaseStruct)
+	}
+
+	txStruct := struct {
+		Txid      string     `json:"txid"`
+		Vout      int        `json:"vout"`
+		ScriptSig *ScriptSig `json:"scriptSig"`
+		Sequence  uint32     `json:"sequence"`
+	}{
+		Txid:      v.Txid,
+		Vout:      v.Vout,
+		ScriptSig: v.ScriptSig,
+		Sequence:  v.Sequence,
+	}
+	return json.Marshal(txStruct)
+}
+
 // Vout models parts of the tx data.  It is defined seperately since both
 // getrawtransaction and decoderawtransaction use the same structure.
 type Vout struct {
@@ -114,9 +144,9 @@ type Vout struct {
 	ScriptPubKey struct {
 		Asm       string   `json:"asm"`
 		Hex       string   `json:"hex"`
-		ReqSigs   int      `json:"reqSigs"`
+		ReqSigs   int      `json:"reqSigs,omitempty"`
 		Type      string   `json:"type"`
-		Addresses []string `json:"addresses"`
+		Addresses []string `json:"addresses,omitempty"`
 	} `json:"scriptPubKey"`
 }