rpc: fix regression in gettransaction

PR 16866 renamed the 'decode' argument in gettransaction to 'verbose' to make it more consistent with other RPC calls like getrawtransaction.

However, it seems it inadvertently overloaded the 'details' fields when 'verbose' is passed. The result is that the original 'details' fields are no longer returned, which seems to be a breaking API change.

This PR takes the simplest path to restoring the 'details' fields by renaming them from 'details' back to 'decoded', while leaving the 'verbose' argument for API consistency.

It also addresses [this comment](https://github.com/bitcoin/bitcoin/pull/16185#discussion_r320740413) to mention that the 'decoded' field is identical to decoderawtransaction.

Update the RPC help, functional test, and release note.

3 files changed, 15 insertions, 9 deletions

diff --git a/doc/release-notes-16185.md b/doc/release-notes-16185.md
index 14e4004f72..2567ebea40 100644
--- a/doc/release-notes-16185.md
+++ b/doc/release-notes-16185.md
@@ -1,3 +1,6 @@
 RPC changes
 -----------
-The `gettransaction` RPC now accepts a third (boolean) argument `verbose`. If set to `true`, a new `details` field will be added to the response containing additional transaction details.
+The `gettransaction` RPC now accepts a third (boolean) argument `verbose`. If
+set to `true`, a new `decoded` field will be added to the response containing
+the decoded transaction. This field is equivalent to RPC `decoderawtransaction`,
+or RPC `getrawtransaction` when `verbose` is passed.
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 9952e868f9..216205ed61 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -1648,8 +1648,10 @@ static UniValue gettransaction(const JSONRPCRequest& request)
                 "\nGet detailed information about in-wallet transaction <txid>\n",
                 {
                     {"txid", RPCArg::Type::STR, RPCArg::Optional::NO, "The transaction id"},
-                    {"include_watchonly", RPCArg::Type::BOOL, /* default */ "true for watch-only wallets, otherwise false", "Whether to include watch-only addresses in balance calculation and details[]"},
-                    {"verbose", RPCArg::Type::BOOL, /* default */ "false", "Whether to add a field with additional transaction details"},
+                    {"include_watchonly", RPCArg::Type::BOOL, /* default */ "true for watch-only wallets, otherwise false",
+                            "Whether to include watch-only addresses in balance calculation and details[]"},
+                    {"verbose", RPCArg::Type::BOOL, /* default */ "false",
+                            "Whether to include a `decoded` field containing the decoded transaction (equivalent to RPC decoderawtransaction)"},
                 },
                 RPCResult{
             "{\n"
@@ -1685,7 +1687,8 @@ static UniValue gettransaction(const JSONRPCRequest& request)
             "    ,...\n"
             "  ],\n"
             "  \"hex\" : \"data\"         (string) Raw data for transaction\n"
-            "  \"details\" : transaction         (json object) Optional, additional transaction details. This object contains the same transaction details as the `getrawtransaction` RPC method\n"
+            "  \"decoded\" : transaction         (json object) Optional, the decoded transaction (only present when `verbose` is passed), equivalent to the\n"
+            "                                                RPC decoderawtransaction method, or the RPC getrawtransaction method when `verbose` is passed.\n"
             "}\n"
                 },
                 RPCExamples{
@@ -1739,9 +1742,9 @@ static UniValue gettransaction(const JSONRPCRequest& request)
     entry.pushKV("hex", strHex);
 
     if (verbose) {
-        UniValue details(UniValue::VOBJ);
-        TxToUniv(*wtx.tx, uint256(), details, false);
-        entry.pushKV("details", details);
+        UniValue decoded(UniValue::VOBJ);
+        TxToUniv(*wtx.tx, uint256(), decoded, false);
+        entry.pushKV("decoded", decoded);
     }
 
     return entry;
diff --git a/test/functional/wallet_basic.py b/test/functional/wallet_basic.py
index 4c3fe3078b..40ad9081ae 100755
--- a/test/functional/wallet_basic.py
+++ b/test/functional/wallet_basic.py
@@ -499,10 +499,10 @@ class WalletTest(BitcoinTestFramework):
         self.nodes[0].setlabel(change, 'foobar')
         assert_equal(self.nodes[0].getaddressinfo(change)['ischange'], False)
 
-        # Test "verbose" field value in gettransaction response
+        # Test "decoded" field value in gettransaction `verbose` response.
         self.log.info("Testing verbose gettransaction...")
         tx = self.nodes[0].gettransaction(txid=txid, verbose=True)
-        assert_equal(tx["details"], self.nodes[0].decoderawtransaction(tx["hex"]))
+        assert_equal(tx["decoded"], self.nodes[0].decoderawtransaction(tx["hex"]))
 
 
 if __name__ == '__main__':