Signing transactions

With Blockstack Connect, you can interact with the Stacks 2.0 blockchain, empowering your users to sign transactions and interact with smart contracts.

This functionality currently operates on the Stacks 2.0 Testnet

The user interface has been designed with developers in mind and prominently displays debug information. STX testnet tokens for paying transaction fees can be obtained for free with the testnet faucet. We will update this functionality and experience for mainnet upon its release.

How it works

For your app’s users to be able to execute a smart contract function, they need to sign and broadcast a transaction. It’s important that users remain in control of the private keys that sign these transactions. Connect provides an easy-to-use workflow that allows your users to securely sign transactions.

Connect allows you to open the authenticator with parameters indicating the details of the transaction - like the smart contract address, function name, and specific arguments. Your users get the chance to see these details, and then sign and broadcast the transaction in a single click. Their transaction will be securely signed and broadcasted onto the Stacks blockchain. After this is done, a callback is fired to allow you to update your app.

Calling Clarity Contract Functions

Once you have a Clarity smart contract built and deployed, you’ll naturally want to allow your app’s users to interact with it.

To initiate a contract call transaction, use the openContractCall function.

import { openContractCall } from '@blockstack/connect';

// Here's an example of options:
const myStatus = 'hey there';
const options = {
  contractAddress: 'ST22T6ZS7HVWEMZHHFK77H4GTNDTWNPQAX8WZAKHJ',
  contractName: 'status',
  functionName: 'write-status!',
  functionArgs: [
    {
      type: 'buff',
      value: myStatus,
    }
  ],
  authOrigin,
  appDetails: {
    name: 'SuperApp',
    icon: 'https://example.com/icon.png'
  },
  finished: (data) => {
    console.log('TX ID:', data.txId);
    console.log('Raw TX:', data.txRaw);
  },
};

await openContractCall(opts);

When calling openContractCall, you need to specify a few details. Here is the exact interface that describes what options you have:

interface ContractCallOptions {
  contractAddress: string;
  functionName: string;
  contractName: string;
  functionArgs?: any[];
  authOrigin?: string;
  appDetails: {
    name: string;
    icon: string;
  };
  finished: (data: FinishedTxData) => void;
}
parameter type optional description
contractAddress string false The Stacks address that published this contract
contractName string false The name that was used when publishing this contract
functionName string false The name of the function you’re calling. This needs to be a public function.
functionArgs array false The arguments you’re calling the function with. You’ll need to provide the Clarity type with each argument. See the below section for details. Defaults to [].
appDetails object false A dictionary that includes name and icon
finished function false A callback that is fired when the transaction is signed and broadcasted. Your callback will receive an object back with a txId and a txRaw, both of which are strings.
authOrigin string true The location of the authenticator. This is only necessary when developing the authenticator locally, or when using beta features. Defaults to "https://app.blockstack.org".

Passing Clarity types with function arguments

To be able to serialize your transaction properly, you need to provide the appropriate Clarity type with each argument. These types are named the same as they are in Clarity. The value that you pass must be a string. The types you can pass are:

  • uint - i.e. "240"
  • int - i.e. "12"
  • bool - can be “true”, “false”, “0” or “1”
  • buff - i.e. "asdf"
  • principal - This can be a contract principal, or a standard principal. Read more about principals. Examples: "ST22T6ZS7HVWEMZHHFK77H4GTNDTWNPQAX8WZAKHJ" or "ST22T6ZS7HVWEMZHHFK77H4GTNDTWNPQAX8WZAKHJ.my-contract".

Using these types, each argument is an object with the keys type and value. For example:

const functionArguments = [
  {
    type: 'buff',
    value: 'hello, world'
  },
  {
    type: 'uint',
    value: '1'
  }
]

If you’re using Typescript, these Clarity types can be imported as ContractCallArgumentType from @blockstack/connect.

Stacks (STX) Token Transfers

STX token transfers can be initiated with the openSTXTransfer function.

import { openSTXTransfer } from '@blockstack/connect';

openSTXTransfer({
  recipient: 'ST2EB9WEQNR9P0K28D2DC352TM75YG3K0GT7V13CV',
  amount: '100',
  memo: 'Testing STX Transfers!',
  authOrigin,
  appDetails: {
    name: 'SuperApp',
    icon: 'https://example.com/icon.png'
  },
  finished: data => {
    console.log(data.txId);
  },
});

When calling openSTXTransfer, you need to specify a few details. Here are the options you have:

interface STXTransferOptions {
  recipient: string;
  amount: string;
  memo?: string;
  authOrigin?: string;
  appDetails: {
    name: string;
    icon: string;
  };
  finished: (data: FinishedTxData) => void;
}
parameter type optional description
recipient string false The STX Address for the recipient of this STX transfer
amount string false The amount of microstacks (µSTX) to be transferred. This argument is a string to prevent floating point errors. There are 1,000,000 µSTX per STX.
memo string true An optional memo to include in the transaction.
appDetails object false A dictionary that includes name and icon
finished function false A callback that is fired when the transaction is signed and broadcasted. Your callback will receive an object back with a txId and a txRaw, both of which are strings.
authOrigin string true The location of the authenticator. This is only necessary when developing the authenticator locally, or when using beta features. Defaults to "https://app.blockstack.org".

Deploying Clarity Contracts

To allow your app’s users to deploy arbitrary Clarity contracts, use the openContractDeploy method.

import { openContractDeploy } from '@blockstack/connect';

const codeBody = '(begin (print "hello, world"))';

openContractDeploy({
  contractName: 'my-contract-name',
  codeBody,
  authOrigin,
  appDetails: {
    name: 'SuperApp',
    icon: 'https://example.com/icon.png'
  },
  finished: (data) => {
    console.log(data.txId);
  }
})

Here is the interface for the options you can provide to openContractDeploy:

interface ContractDeployOptions {
  codeBody: string;
  contractName: string;
  authOrigin?: string;
  appDetails: {
    name: string;
    icon: string;
  };
  finished: (data: FinishedTxData) => void;
}
parameter type optional description
codeBody string false The Clarity source code for this contract
contractName string false The name for this contract
appDetails object false A dictionary that includes name and icon
finished function false A callback that is fired when the transaction is signed and broadcasted. Your callback will receive an object back with a txId and a txRaw, both of which are strings.
authOrigin string true The location of the authenticator. This is only necessary when developing the authenticator locally, or when using beta features. Defaults to "https://app.blockstack.org".

Usage in React Apps

Make sure you follow the setup instructions first. When you’re using useConnect, you don’t have to specify appDetails - we’ll pick that up from your existing configuration.

Each transaction signing method is exposed through the useConnect hook, but they’re prefixed with do instead of open, to remain consistent with our React action naming standards.

import { useConnect } from '@blockstack/connect';

const MyComponent = () => {
  const { doContractCall } = useConnect();

  const onClick = async () => {
    const opts = { /** See examples above */};
    await doContractCall(opts);
  }

  return (
    <span onClick={onClick}>Call my contract</span>
  );
};

Checking transaction status

You may want to check the status of a transaction after signing and broadcasting it. For instance, your app might want to enable certain components only after a transaction was successfully processed on the blockchain.

Following the steps above, you’ll receive a transaction ID (txId) as part of the finished callback method once your user signed the transaction. Equipped with the ID, you can use the Stacks Blockstack API to request the status of the transaction.

const response = await fetch(`https://sidecar.staging.blockstack.xyz/sidecar/v1/tx/${txId}`)
const txData = await response.json();
console.log(txData.status);

The API will respond with a JSON object that includes a tx_status field. Once the response returns success, the transactions was successfully processed.

Note: Review the API reference of the Get Transaction endpoint for more details.