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How to check if an address is a Universal Profile?

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You may want to read the Standard Detection page first.

To check if an address is a Universal Profile we need to perform 3 checks:

Setup​

Make sure you have the following dependencies installed before beginning this tutorial:

Install the dependencies
npm install web3 @lukso/lsp-smart-contracts

Step 1 - Check address format​

This first basic test can be performed via regular expression or 3rd party library function. For example this is how we can achieve this using Web3.js isAddress:

import { isAddress } from 'web3-utils';

if (!isAddress(address)) {
  throw new Error('Invalid address');
}

Step 2 - Check if the contract supports the LSP0ERC725Account interface using ERC165​

This is next check that makes sure we deal with a smart contract that supports the LSP0ERC725Account interface (EIP-165). For this we need to create an universalProfile contract instance and call supportsInterface(...) method.

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Universal Profiles inherit ERC165, therefore by creating an instance of the Universal Profile contract you have access to the supportsInterface(...) method.

import UniversalProfile from '@lukso/lsp-smart-contracts/artifacts/UniversalProfile.json';
import { INTERFACE_IDS } from '@lukso/lsp-smart-contracts/constants';
import Web3 from 'web3';

const web3 = new Web3('https://rpc.testnet.lukso.network');

const universalProfileAddress = '0x...'; // The address of the contract that you are verifying
const universalProfile = new web3.eth.Contract(UniversalProfile.abi, universalProfileAddress);

const supportsLSP0Interface = await universalProfile.methods.supportsInterface(INTERFACE_IDS.LSP0ERC725Account).call();
// true or false -> if false, this address is not a Universal Profile.
if (!supportsLSP0Interface) {
  throw new Error('Contract does not support LSP0ERC725Account interface');
}

Step 3 - Check supported standard​

Last but not least we should perform a check over LSP3UniversalProfile standard. For this we need to call getData with the SupportedStandards:LSP3UniversalProfile key.

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Universal Profiles inherit ERC725Y, therefore by creating an instance of the Universal Profile contract you have access to the getData(..) method.

import UniversalProfile from '@lukso/lsp-smart-contracts/artifacts/UniversalProfile.json';
import { SupportedStandards } from '@lukso/lsp-smart-contracts/constants';
import Web3 from 'web3';

const web3 = new Web3('https://rpc.testnet.lukso.network');

const universalProfileAddress = "0x..."; // The address of the contract that you are verifying
const universalProfile = new web3.eth.Contract(UniversalProfile.abi, universalProfileAddress);

const supportedStandard = await universalProfile.methods['getData(bytes32)'](SupportedStandards.LSP3UniversalProfile.key).call();

if (supportedStandard !== SupportedStandards.LSP3UniversalProfile.value) {
  throw new Error('Address does not support LSP3UniversalProfile standard');
}

Final Code​

import UniversalProfile from '@lukso/lsp-smart-contracts/artifacts/UniversalProfile.json';
import { INTERFACE_IDS, SupportedStandards } from '@lukso/lsp-smart-contracts/constants';
import Web3 from 'web3';

const web3 = new Web3('https://rpc.testnet.lukso.network');

if (!web3.utils.isAddress(address)) {
  throw new Error('Invalid address');
}

// We assume that the contract is a Universal Profile
const universalProfileAddress = '0x...'; // The address of the contract that you are verifying
const universalProfile = new web3.eth.Contract(UniversalProfile.abi, universalProfileAddress);

const supportsLSP0Interface = await universalProfile.methods.supportsInterface(INTERFACE_IDS.LSP0ERC725Account).call();
// true or false -> if false, this address is not a Universal Profile.
if (!supportsLSP0Interface) {
  throw new Error('Contract does not support LSP0ERC725Account interface');
}

const supportedStandard = await universalProfile.methods['getData(bytes32)'](SupportedStandards.LSP3UniversalProfile.key).call();

if (supportedStandard !== SupportedStandards.LSP3UniversalProfile.value) {
  throw new Error('Address does not support LSP3UniversalProfile standard');
}