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Using invite codes with on-chain groups

This tutorial will guide you through the complete process of adding a user to an on-chain group via invite codes.

Install library​

npm install @bandada/utils

Create a new instance​

After installing the utils package, create a new instance of Semaphore.

More details on the utils package can be found here.

  • Create a new instance of Semaphore contract.
import { getSemaphoreContract } from "@bandada/utils"

const semaphore = getSemaphoreContract("sepolia")
  • Create a new instance of Semaphore contract with signer.
import { getSemaphoreContract } from "@bandada/utils"
import { useSigner } from "wagmi"

const { data: signer } = useSigner()

const semaphore = getSemaphoreContract("sepolia", signer)

You can choose to use other signer package of your choice, wagmi is just an example.

Create a group​

Create a new on-chain group with associated group.

const semaphore = getSemaphoreContract("sepolia", signer as any)
const admin = await signer.getAddress()

// create on-chain group
const receipt = await semaphore.createGroup(admin)

const groupIdBigNumber = receipt.events?.[0]?.args?.[0].toString()
const onchainGroupId = groupIdBigNumber.toString()

const apiKey = "your-api-key"
const groupCreationDetails = {
    name: onchainGroupId,
    description: `This group is associated to the on-chain group ${onchainGroupId}`,
    treeDepth: 16,
    fingerprintDuration: 3600
}

// create associated group
const group = apiSdk.createGroup(groupCreationDetails, apiKey)

Add members to on-chain group using invite code​

Create a new group invite.

const groupId = "your-associated-group-id"
const apiKey = "your-api-key"

const invite = await apiSdk.createInvite(groupId, apiKey)

Add member using an invite code​

Adds a member to an on-chain group using an invite code.

const groupId = "your-group-id"
const memberId = "member-id"
const inviteCode = "INVITECODE"

const group = await semaphore.getGroup(groupId, {
    members: true
})

const invite = await apiSdk.getInvite(inviteCode)
const apiKey = "your-api-key"

if(invite.isRedeemed) {
    throw new Error(`Invite code '${inviteCode}' has already been redeemed`)
} else {
    await semaphore.addMember(group.id, memberId)
    
    await apiSdk.redeemInvite(inviteCode, invite.group.id, apiKey)
}

Full example​

This is an example of how the whole code would look like:

import { getSemaphoreContract } from "@bandada/utils"
import { ApiSdk, SupportedUrl } from "@bandada/api-sdk"
import { useSigner } from "wagmi"

const apiSdk = new ApiSdk(SupportedUrl.DEV)
const semaphore = getSemaphoreContract("sepolia", signer as any)
const { data: signer } = useSigner()

const admin = await signer.getAddress()

// create on-chain group
const receipt = await semaphore.createGroup(admin)

const groupIdBigNumber = receipt.events?.[0]?.args?.[0].toString()
const onchainGroupId = groupIdBigNumber.toString()

const apiKey = "your-api-key"
const memberId = "member-id-1"

const groupCreationDetails = {
    name: onchainGroupId,
    description: `This group is associated to the on-chain group ${onchainGroupId}`,
    treeDepth: 16,
    fingerprintDuration: 3600
}

// create associated group
const associatedGroup = apiSdk.createGroup(groupCreationDetails, apiKey)

// generate invite code with the associated group id
const invite = await apiSdk.createInvite(associatedGroup.id, apiKey)

// check if the invite code has been redeemed
if(invite.isRedeemed) {
    throw new Error(`Invite code '${invite.code}' has already been redeemed`)
} else {
    // add member to on-chain group
    await semaphore.addMember(onchainGroupId, memberId)

    // redeem the invite code after successfully adding the member to the on-chain group
    await apiSdk.redeemInvite(invite.code, associatedGroup.id, apiKey)
}