Preparing Transactions

All transactions sent with the SDK need to be prepared first. Preparing a transaction is synchronous, lightweight and does not require any network requests. It also gives you type-safe definitions for your contract calls.

The recommended way to prepare a contract call is to pass the Solidity method signature and the params. This is type-safe based on the Solidity method signature you define. You can get your desired contract method signature from the solidity code directly.

import { prepareContractCall, toWei } from "thirdweb";
 
const tx = prepareContractCall({
  contract,
  // Pass the method signature that you want to call
  method: "function mintTo(address to, uint256 amount)",
  // and the params for that method
  // Their types are automatically inferred based on the method signature
  params: ["0x123...", toWei("100")],
});

This will return a prepared transaction object that is ready to be sent to the blockchain and can be acted on in various ways.

You can also create a raw transaction directly. This is useful when you want to send ether to an address for example, or when you already have encoded data.

import { prepareTransaction, toWei } from "thirdweb";
 
const transaction = prepareTransaction({
  // The account that will be the receiver
  to: "0x456...",
  // The value is the amount of ether you want to send with the transaction
  value: toWei("1"),
});

There are few other ways to prepare a contract call, all of these return the same transaction object.

Using the CLI, you can generate optimized functions for all the possible calls to a contract. This saves you time and precomputes all the necessary encoding.

npx thirdweb generate <contractId>/<contractAddress>

Read more on how to generate extension functions using the CLI.

Another way to get type safety is to pass the full contract ABI to getContract. This will give you autocompletion for all methods declared in the ABI. There is a slight extract cost of having the full ABI in your code which can be pretty large.

import { getContract, prepareContractCall, toWei } from "thirdweb";
 
const contract = getContract({
  client,
	chainId,
  // The ABI for the contract is defined here
  abi: [
    ...
    {
      name: "mintTo",
      inputs: [
        {
          type: "address",
          name: "to",
        },
        {
          type: "uint256",
          name: "amount",
        },
      ],
      type: "function",
    }
    ...
  ],
});
 
const tx = prepareContractCall({
  contract,
  // We get auto-completion for all the available functions on the contract ABI
  method: "mintTo",
  // including full type-safety for the params
  params: ["0x123...", toWei("100")],
});

As an alternative to passing the full ABI, you can pass a snippet of the ABI for the method you want to call. This is useful when you only want to call a single method and don't want to have the full ABI in your code.

import { prepareContractCall, toWei } from "thirdweb";
 
const tx = prepareContractCall({
  contract,
  // Pass a snippet of the ABI for the method you want to call.
  method: {
    name: "mintTo",
    inputs: [
      {
        type: "address",
        name: "to",
      },
      {
        type: "uint256",
        name: "amount",
      },
    ],
    type: "function",
  },
  // The Types of `params` are automatically inferred based on the ABI inputs.
  params: ["0x123...", toWei("100")],
});

Finally, you can dynamically resolve contract methods at runtime using the resolveMethod function. This is the best way to handle contracts you don't know the ABI of in advance but it is also less performant and not type-safe.

import { prepareContractCall, resolveMethod, toWei } from "thirdweb";
const tx = prepareContractCall({
  contract,
  // in this case we only pass the name of the method we want to call
  method: resolveMethod("mintTo"),
  // however using this method we lose type safety for our params
  params: ["0x123...", toWei("100")],
});