result.pushKV("hex", strHex);

// validation.cpp
bool GetTransaction(const uint256 &hash, CTransactionRef &txOut, const Consensus::Params& consensusParams, uint256 &hashBlock, bool fAllowSlow, CBlockIndex* blockIndex)
{
    CBlockIndex *pindexSlow = blockIndex;

    LOCK(cs_main);

    if (!blockIndex) {
        CTransactionRef ptx = mempool.get(hash);
        if (ptx) {
            txOut = ptx;
            return true;
        }
        if (fTxIndex) {
            CDiskTxPos postx;
            if (pblocktree->ReadTxIndex(hash, postx)) {
                CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION);
                if (file.IsNull())
                    return error("%s: OpenBlockFile failed", __func__);
                CBlockHeader header;
                try {
                    file >> header;
                    fseek(file.Get(), postx.nTxOffset, SEEK_CUR);
                    file >> txOut;
                } catch (const std::exception& e) {
                    return error("%s: Deserialize or I/O error - %s", __func__, e.what());
                }
                hashBlock = header.GetHash();
                if (txOut->GetHash() != hash)
                    return error("%s: txid mismatch", __func__);
                return true;
            }
        }
        if (fAllowSlow) { // use coin database to locate block that contains transaction, and scan it
            int nHeight = -1;
            {
                const CCoinsViewCache& view = *pcoinsTip;
                const CCoins* coins = view.AccessCoins(hash);
                if (coins)
                    nHeight = coins->nHeight;
            }
            if (nHeight > 0)
                pindexSlow = chainActive[nHeight];
        }
    }


    if (pindexSlow) {
        CBlock block;
        if (ReadBlockFromDisk(block, pindexSlow, consensusParams)) {
            for (const auto& tx : block.vtx) {
                if (tx->GetHash() == hash) {
                    txOut = tx;
                    hashBlock = pindexSlow->GetBlockHash();
                    return true;
                }
            }
        }
    }

    return false;
}

// validation.h
bool GetTransaction(const uint256 &hash, CTransactionRef &tx, const Consensus::Params& params, uint256 &hashBlock, bool fAllowSlow = false, CBlockIndex* blockIndex = nullptr);