Developer Fundamentals

4. Clauses and Fuel Calc

Build multi-clause tx and estimate VTHO gas precisely.

Prerequisites

Crafting Clauses & Gas

Instructions inside the envelope? Clauses! 📬 VeChain bundles multiples for efficiency.

Ok, so…

You weren't expecting to code manually each clause, right? Fortunatelly we have a Clause builder.

Encode clauses:

import { Clause, ABIFunction } from '@vechain/sdk-core';

const clauses = [
  Clause.callFunction('0x8384738c...', 
  new ABIFunction({ name: 'increment', type: 'function' })),
  // Add more clauses!
];

import { Clause, ABIFunction } from '@vechain/sdk-core';

const clauses = [
  Clause.callFunction('0x8384738c...', 
  new ABIFunction({ name: 'increment', type: 'function' })),
  // Add more clauses!
];

import { Clause, ABIFunction } from '@vechain/sdk-core';

const clauses = [
  Clause.callFunction('0x8384738c...', 
  new ABIFunction({ name: 'increment', type: 'function' })),
  // Add more clauses!
];

The other part you know, you estimate gas and get the transaction body:

const gasResult = await thor.transactions.estimateGas(clauses);
const txBody = await thor.transactions.buildTransactionBody(clauses, gasResult.totalGas);

const gasResult = await thor.transactions.estimateGas(clauses);
const txBody = await thor.transactions.buildTransactionBody(clauses, gasResult.totalGas);

const gasResult = await thor.transactions.estimateGas(clauses);
const txBody = await thor.transactions.buildTransactionBody(clauses, gasResult.totalGas);

Multi-power activated!

Note for nerds!

In the example we've used ABIFunction, which requires to know the properties of the contract function we wish to use. The alternative is to load the ABI:

import Abi from './abi.json' assert { type: 'json' };
// contract ABI is same as in example above
const vtho = thor.contracts.load(
    '0x8384738c...',
    Abi
)

const clauses = [
  vtho.clause.increment().clause,
  // Add more clauses!
]

import Abi from './abi.json' assert { type: 'json' };
// contract ABI is same as in example above
const vtho = thor.contracts.load(
    '0x8384738c...',
    Abi
)

const clauses = [
  vtho.clause.increment().clause,
  // Add more clauses!
]

import Abi from './abi.json' assert { type: 'json' };
// contract ABI is same as in example above
const vtho = thor.contracts.load(
    '0x8384738c...',
    Abi
)

const clauses = [
  vtho.clause.increment().clause,
  // Add more clauses!
]

Signing seals it!

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