refactor: Introduce TxDocOptions

This prepares the function to be more flexible, when more options are
passed in the future.

src/rpc/rawtransaction.cpp

@@ -248,7 +248,7 @@ static RPCHelpMan getrawtransaction()
                              {RPCResult::Type::NUM, "time", /*optional=*/true, "Same as \"blocktime\""},
                              {RPCResult::Type::STR_HEX, "hex", "The serialized, hex-encoded data for 'txid'"},
                          },
-                         DecodeTxDoc(/*txid_field_doc=*/"The transaction id (same as provided)", /*wallet=*/false)),
+                         TxDoc({.txid_field_doc="The transaction id (same as provided)"})),
                     },
                     RPCResult{"for verbosity = 2",
                         RPCResult::Type::OBJ, "", "",
@@ -422,7 +422,7 @@ static RPCHelpMan decoderawtransaction()
                 },
                 RPCResult{
                     RPCResult::Type::OBJ, "", "",
-                    DecodeTxDoc(/*txid_field_doc=*/"The transaction id", /*wallet=*/false),
+                    TxDoc(),
                 },
                 RPCExamples{
                     HelpExampleCli("decoderawtransaction", "\"hexstring\"")

src/rpc/rawtransaction_util.cpp

@@ -344,10 +344,10 @@ void SignTransactionResultToJSON(CMutableTransaction& mtx, bool complete, const
     }
 }
 
-std::vector<RPCResult> DecodeTxDoc(const std::string& txid_field_doc, bool wallet)
+std::vector<RPCResult> TxDoc(const TxDocOptions& opts)
 {
     return {
-        {RPCResult::Type::STR_HEX, "txid", txid_field_doc},
+        {RPCResult::Type::STR_HEX, "txid", opts.txid_field_doc},
         {RPCResult::Type::STR_HEX, "hash", "The transaction hash (differs from txid for witness transactions)"},
         {RPCResult::Type::NUM, "size", "The serialized transaction size"},
         {RPCResult::Type::NUM, "vsize", "The virtual transaction size (differs from size for witness transactions)"},
@@ -381,7 +381,7 @@ std::vector<RPCResult> DecodeTxDoc(const std::string& txid_field_doc, bool walle
                     {RPCResult::Type::NUM, "n", "index"},
                     {RPCResult::Type::OBJ, "scriptPubKey", "", ScriptPubKeyDoc()},
                 },
-                    wallet ?
+                    opts.wallet ?
                     std::vector<RPCResult>{{RPCResult::Type::BOOL, "ischange", /*optional=*/true, "Output script is change (only present if true)"}} :
                     std::vector<RPCResult>{}
                 )

src/rpc/rawtransaction_util.h

@@ -56,7 +56,13 @@ void AddOutputs(CMutableTransaction& rawTx, const UniValue& outputs_in);
 /** Create a transaction from univalue parameters */
 CMutableTransaction ConstructTransaction(const UniValue& inputs_in, const UniValue& outputs_in, const UniValue& locktime, std::optional<bool> rbf, uint32_t version);
 
+struct TxDocOptions {
+    /// The description of the txid field
+    std::string txid_field_doc{"The transaction id"};
+    /// Include wallet-related fields (e.g. ischange on outputs)
+    bool wallet{false};
+};
 /** Explain the UniValue "decoded" transaction object, may include extra fields if processed by wallet **/
-std::vector<RPCResult> DecodeTxDoc(const std::string& txid_field_doc, bool wallet);
+std::vector<RPCResult> TxDoc(const TxDocOptions& opts = {});
 
 #endif // BITCOIN_RPC_RAWTRANSACTION_UTIL_H

src/wallet/rpc/transactions.cpp

@@ -705,7 +705,7 @@ RPCHelpMan gettransaction()
                         {RPCResult::Type::STR_HEX, "hex", "Raw data for transaction"},
                         {RPCResult::Type::OBJ, "decoded", /*optional=*/true, "The decoded transaction (only present when `verbose` is passed)",
                         {
-                            DecodeTxDoc(/*txid_field_doc=*/"The transaction id", /*wallet=*/true),
+                            TxDoc({.wallet = true}),
                         }},
                         RESULT_LAST_PROCESSED_BLOCK,
                     })