Unified Tx API

Preview — 0.8.0-preview1: APIs may change before stable release.

What Changed

In previous versions, building transactions required choosing between two classes:

Tx — for regular payments, native token minting, staking, and governance
ScriptTx — for Plutus script inputs, Plutus minting, and validator attachment

Starting in 0.8.0, all ScriptTx operations are now available directly on Tx. The ScriptTx class is deprecated and will be removed in a future release.

Why

No more class-choice burden — you don’t need to decide upfront whether your transaction involves scripts
Mix operations freely — combine script inputs, Plutus minting, native payments, and staking in a single Tx
Drop-in migration — replace new ScriptTx() with new Tx() and everything works

New Methods on Tx

Script Input Collection


// Collect from script UTXOs with redeemer and optional datum
tx.collectFrom(utxo, redeemer, datum)
tx.collectFrom(utxoList, redeemer, datum)
tx.collectFrom(utxo, redeemer)
tx.collectFrom(utxoList, redeemer)
 
// Predicate-based script UTXO selection
tx.collectFrom(scriptAddress, utxo -> utxo.getAmount().contains("token"), redeemer, datum)
 
// Filter-based script UTXO selection
tx.collectFrom(scriptAddress, filterSpec, redeemer, datum)

Reference Inputs


// Read reference inputs (no spending)
tx.readFrom(utxo1, utxo2)
tx.readFrom(transactionInput)
tx.readFrom(txHash, outputIndex)

Plutus Minting


// Mint with Plutus script (singular: mintAsset)
tx.mintAsset(plutusScript, asset, redeemer)
tx.mintAsset(plutusScript, assets, redeemer, receiver)
tx.mintAsset(plutusScript, assets, redeemer, receiver, outputDatum)
 
// Mint via reference script (by policy ID)
tx.mintAsset(policyId, asset, redeemer)
tx.mintAsset(policyId, assets, redeemer, receiver)

Note: Native script minting continues to use mintAssets (plural), while Plutus minting uses mintAsset (singular).

Validator Attachment


tx.attachSpendingValidator(plutusScript)
tx.attachMintValidator(plutusScript)
tx.attachCertificateValidator(plutusScript)
tx.attachRewardValidator(plutusScript)
tx.attachProposingValidator(plutusScript)
tx.attachVotingValidator(plutusScript)

Change Address with Datum


tx.withChangeAddress(address, inlineDatum)
tx.withChangeAddress(address, datumHash)

Script-Protected Stake Operations


// Deregister with redeemer
tx.deregisterStakeAddress(stakeAddr, redeemer)
 
// Delegate with redeemer
tx.delegateTo(stakeAddr, poolId, redeemer)
 
// Withdraw with redeemer
tx.withdraw(rewardAddr, amount, redeemer)
tx.withdraw(rewardAddr, amount, redeemer, receiver)

Script-Protected Governance Operations


tx.registerDRep(credential, anchor, redeemer)
tx.unRegisterDRep(credential, refundAddress, refundAmount, redeemer)
tx.updateDRep(credential, anchor, redeemer)
tx.createProposal(govAction, returnAddress, anchor, redeemer)
tx.createVote(voter, govActionId, vote, anchor, redeemer)
tx.delegateVotingPowerTo(address, dRep, redeemer)

Usage Examples

Script Input with Payment


Tx tx = new Tx()
        .collectFrom(scriptUtxo, redeemer)
        .attachSpendingValidator(spendingScript)
        .payToAddress(receiver, Amount.ada(10))
        .from(senderAddress);
 
TxResult result = quickTxBuilder.compose(tx)
        .withSigner(SignerProviders.signerFrom(sender))
        .completeAndWait();

Reference Inputs


Tx tx = new Tx()
        .collectFrom(scriptUtxo, redeemer)
        .readFrom(referenceUtxo)           // Reference input for inline datum/script
        .payToAddress(receiver, Amount.ada(5))
        .from(senderAddress);

Plutus Minting


Asset token = Asset.builder()
        .name("MyPlutusToken")
        .value(BigInteger.valueOf(100))
        .build();
 
Tx tx = new Tx()
        .mintAsset(mintingScript, token, PlutusData.unit(), receiverAddress)
        .from(senderAddress);
 
TxResult result = quickTxBuilder.compose(tx)
        .withSigner(SignerProviders.signerFrom(sender))
        .completeAndWait();

Mixed Operations in One Transaction


// Combine native payment, Plutus minting, and script input in a single Tx
Tx tx = new Tx()
        .payToAddress(receiver1, Amount.ada(5))              // Native payment
        .mintAsset(mintScript, token, PlutusData.unit())     // Plutus minting
        .collectFrom(scriptUtxo, spendRedeemer)              // Script input
        .attachSpendingValidator(spendingScript)
        .from(senderAddress);

Migration Guide

Replacing ScriptTx with Tx is a drop-in change. The method names and signatures are identical.

Before (0.7.x)


ScriptTx scriptTx = new ScriptTx()
        .collectFrom(scriptUtxo, redeemer, datum)
        .payToAddress(receiver, Amount.ada(10))
        .attachSpendingValidator(validator);
 
quickTxBuilder.compose(scriptTx)
        .withSigner(SignerProviders.signerFrom(sender))
        .completeAndWait();

After (0.8.0)


Tx tx = new Tx()
        .collectFrom(scriptUtxo, redeemer, datum)
        .payToAddress(receiver, Amount.ada(10))
        .attachSpendingValidator(validator)
        .from(senderAddress);
 
quickTxBuilder.compose(tx)
        .withSigner(SignerProviders.signerFrom(sender))
        .completeAndWait();

The only required addition is .from(senderAddress) to set the fee payer, which ScriptTx handled differently (via package-private methods).

How Detection Works

You don’t need to configure anything. When QuickTxBuilder processes a Tx, it automatically detects whether the transaction involves scripts by checking hasScriptIntents() — a data-driven inspection of the transaction’s intentions list. If any script-related intents are present (script inputs, Plutus minting, or validator attachments), the builder applies script-specific processing (collateral selection, execution unit evaluation, etc.) automatically.

Comparison

Aspect	Before (0.7.x)	After (0.8.0)
Class choice	`Tx` for regular, `ScriptTx` for scripts	`Tx` for everything
Script inputs	`ScriptTx.collectFrom(utxo, redeemer)`	`Tx.collectFrom(utxo, redeemer)`
Plutus minting	`ScriptTx.mintAsset(script, asset, redeemer)`	`Tx.mintAsset(script, asset, redeemer)`
Validator attachment	`ScriptTx.attachSpendingValidator(script)`	`Tx.attachSpendingValidator(script)`
Mixing operations	Compose separate `Tx` + `ScriptTx`	Single `Tx` with all operations
Backward compatibility	N/A	`ScriptTx` still works (deprecated)