user725: I looked through the Plutus GitHub and found some info, but I cannot decode it.plutus/plutus-ledger/src/Ledger/Tx.hs
Here it is:
  encode (SomeTx tx eraInMode) = encodedMode eraInMode <> Encoding (TkBytes (C.serialiseToCBOR tx))
    where
      encodedMode :: C.EraInMode era C.CardanoMode -> Encoding
      -- 0 and 1 are for ByronEraInByronMode and ShelleyEraInShelleyMode
      encodedMode C.ByronEraInCardanoMode   = Encoding (TkSimple 2)
      encodedMode C.ShelleyEraInCardanoMode = Encoding (TkSimple 3)
      encodedMode C.AllegraEraInCardanoMode = Encoding (TkSimple 4)
      encodedMode C.MaryEraInCardanoMode    = Encoding (TkSimple 5)
      encodedMode C.AlonzoEraInCardanoMode  = Encoding (TkSimple 6)
  decode = do
    w <- decodeSimple
    case w of
      2 -> decodeTx C.AsByronEra C.ByronEraInCardanoMode
      3 -> decodeTx C.AsShelleyEra C.ShelleyEraInCardanoMode
      4 -> decodeTx C.AsAllegraEra C.AllegraEraInCardanoMode
      5 -> decodeTx C.AsMaryEra C.MaryEraInCardanoMode
      6 -> decodeTx C.AsAlonzoEra C.AlonzoEraInCardanoMode
      _ -> fail "Unexpected value while decoding Cardano.Api.EraInMode"
    where
      decodeTx :: C.IsCardanoEra era => C.AsType era -> C.EraInMode era C.CardanoMode -> Decoder s SomeCardanoApiTx
      decodeTx asType eraInMode = do
        bytes <- decodeBytes
        tx <- either (const $ fail "Failed to decode Cardano.Api.Tx") pure $ C.deserialiseFromCBOR (C.AsTx asType) bytes
        pure $ SomeTx tx eraInMode

How do you go about using something like this?
Thanks!

user705: The answer is no.
A TxId is hash digest (blake2b-256) of the serialized transaction body. By construction, a hash is non-reversible (https://en.wikipedia.org/wiki/Cryptographic_hash_function).
In order to find back a transaction from a TxId, you need an index which keeps track of transactions and enable looking them up.

725: <p>I looked through the Plutus GitHub and found some info, but I cannot decode it.<a href="https://github.com/input-output-hk/plutus/blob/1efbb276ef1a10ca6961d0fd32e6141e9798bd11/plutus-ledger/src/Ledger/Tx.hs" rel="nofollow noreferrer">plutus/plutus-ledger/src/Ledger/Tx.hs</a></p>
<p>Here it is:</p>
<pre><code>  encode (SomeTx tx eraInMode) = encodedMode eraInMode &lt;&gt; Encoding (TkBytes (C.serialiseToCBOR tx))
    where
      encodedMode :: C.EraInMode era C.CardanoMode -&gt; Encoding
      -- 0 and 1 are for ByronEraInByronMode and ShelleyEraInShelleyMode
      encodedMode C.ByronEraInCardanoMode   = Encoding (TkSimple 2)
      encodedMode C.ShelleyEraInCardanoMode = Encoding (TkSimple 3)
      encodedMode C.AllegraEraInCardanoMode = Encoding (TkSimple 4)
      encodedMode C.MaryEraInCardanoMode    = Encoding (TkSimple 5)
      encodedMode C.AlonzoEraInCardanoMode  = Encoding (TkSimple 6)
  decode = do
    w &lt;- decodeSimple
    case w of
      2 -&gt; decodeTx C.AsByronEra C.ByronEraInCardanoMode
      3 -&gt; decodeTx C.AsShelleyEra C.ShelleyEraInCardanoMode
      4 -&gt; decodeTx C.AsAllegraEra C.AllegraEraInCardanoMode
      5 -&gt; decodeTx C.AsMaryEra C.MaryEraInCardanoMode
      6 -&gt; decodeTx C.AsAlonzoEra C.AlonzoEraInCardanoMode
      _ -&gt; fail &quot;Unexpected value while decoding Cardano.Api.EraInMode&quot;
    where
      decodeTx :: C.IsCardanoEra era =&gt; C.AsType era -&gt; C.EraInMode era C.CardanoMode -&gt; Decoder s SomeCardanoApiTx
      decodeTx asType eraInMode = do
        bytes &lt;- decodeBytes
        tx &lt;- either (const $ fail &quot;Failed to decode Cardano.Api.Tx&quot;) pure $ C.deserialiseFromCBOR (C.AsTx asType) bytes
        pure $ SomeTx tx eraInMode
</code></pre>
<p>How do you go about using something like this?</p>
<p>Thanks!</p>
 705: <p>The answer is no.</p>
<p>A TxId is hash digest (blake2b-256) of the serialized transaction body. By construction, a hash is non-reversible (<a href="https://en.wikipedia.org/wiki/Cryptographic_hash_function" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Cryptographic_hash_function</a>).</p>
<p>In order to find back a transaction from a TxId, you need an index which keeps track of transactions and enable looking them up.</p>
