Creating an account, adding a trust line and transferring the asset in a single transaction

Question

I want to send non-native assets to new stellar accounts. To do this, I understand that I need to create a new account by funding it with XLM (1 XLM minimum), add a trust line to the asset issuer and then transfer the asset from my account to the new account. I want to do this in one transaction. This is what I have so far:

var sourceKeys = StellarSdk.Keypair.fromSecret(sourceaccountkey);
let builder = new StellarSdk.TransactionBuilder(sourceAccount);
builder.addOperation(StellarSdk.Operation.createAccount({
    destination: destinationId,
    startingBalance: sendamount
}));

// This operation needs to be done on the receiver account, but the builder object belongs to the source account
builder.addOperation(
    StellarSdk.Operation.changeTrust({
        asset: new StellarSDK.Asset(assetcode, assetissueraddress)
    })
);

// Assuming the above is even possible, how do I sign with both source and receiver account keys?
transaction.sign(sourceKeys);

Any help is much appreciated. Thanks.

Answer 1

1. Prepare keypairs for all participating accounts - source account and destination account.

let source = StellarSdk.Keypair.fromSecret(sourceAccountSecretKey)
let dest = StellarSdk.Keypair.fromSecret(destinationAccountSecretKey)

Keypair for the destination account can be generated using StellarSdk.Keypair.random().

2. Load current source account state from Horizon server

let sourceAccount = await horizon.loadAccount(source.publicKey())

3. Create a transaction builder

let builder = new StellarSdk.TransactionBuilder(sourceAccount)

4. Add CREATE_ACCOUNT operation

builder.addOperation(StellarSdk.Operation.createAccount({
     destination: dest.publicKey(),
     startingBalance: '1.6'
}))

The starting balance should be enough to satisfy the minimum account balance requirement(1 XLM), trustline reserve (0.5 XLM), and a few more stroops to pay transaction fees (0.1 XLM).

5. Add CHANGE_TRUST operation to establish trustline

builder.addOperation(StellarSdk.Operation.changeTrust({ 
    asset: new StellarSDK.Asset(assetCode, assetIssuerAddress),
    source: dest.publicKey()
}))

Note that source parameter contains a public key of our destination account because we perform this operation on behalf of the destination account.

6. Add PAYMENT operation to transfer your custom asset

builder.addOperation(StellarSdk.Operation.payment({ 
    destination: dest.publicKey(),
    asset: new StellarSDK.Asset(assetCode, assetIssuerAddress),
    amount: '100'
}))

7. Build and sign transaction with both source and destination keypairs

let tx = builder.build()

tx.sign(source)
tx.sign(dest)

8. Submit transaction to network

let txResult = await horizon.submitTransaction(tx)

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Also check the detailed walkthrough describing the basic account creation process.