Token Playground Chapter 7 : Mint from a wrapped token in Soroban.

• Check this guide in https://token-playground.gitbook.io/
• Edit this guide in it's repo: https://github.com/esteblock/token-playground/
• Contribute to this guide in the ./docs folder of the repo

1. Introduction

In the previous chapters we have already:

• Issued a (classic) Stellar Assets in the (classic) Stellar blockchain.
• Wrapped this asset into a SAC (Stellar Asset Contract) token into Soroban

In this chapter we will mint some units of this SAC token inside the Soroban chain, so this token can be used by smart contracts!

2. Setting up your soroban-cli

Configure your soroban-cli to use the token-admin identity

soroban config identity address token-admin

Check last chapter if you don't know what this means.

3. Smart Contract ID

From last chapter, you'll need to have your SAC's id, that can be something like this:

86b9acd9860d105c2b5e6b688ab0fce5f9c45516dcc704f9427936c79384e72f

If you followed our Token Playground's code, you should have this id inside the .soroban/token_id file

TOKEN_ID=$(cat .soroban/token_id)

3. Destination address

As when issuing an asset in Stellar Classic, in order to mint a token in Soroban, you need to send units of this token to some receiver, hence we will set a receiver address:

DESTINATION_ADDRESS=SBFJKSFA5YK2SUAVVSMEKDA44MYCBFSNNAORJSO7J437HJWU6G7SGAVF

If you are following our code, and you are using the settings.json file, you can do

DESTINATION_ADDRESS=$(cat ./settings.json | jq  -r '.receiverPublic' )

4. The xfer function

In order to mint, we will use the soroban invoke command in the soroban-cli in order to invoke a function inside the SAC contract.

The transfer function in a SAC contract is the xfer function and receives 3 arguments:

• from
• to
• amount

Here is a piece of code of the SAC contract

fn xfer(e: Env, from: Address, to: Address, amount: i128) {
        from.require_auth();

        check_nonnegative_amount(amount);
        spend_balance(&e, from.clone(), amount);
        receive_balance(&e, to.clone(), amount);
        event::transfer(&e, from, to, amount);
    } 

If you want to learn more about the SAC code in the Stellar guide

5. Invoke the xfer function and mint the token

If we invoke the xfer function from the issuer we will actually mint some units of the token, hence, we will do:

TOKEN_ADMIN_SECRET=$(cat ./settings.json | jq -r '.issuerSecret' )

NETWORK="standalone"

soroban contract invoke \
  --network $NETWORK --identity token-admin \
  --wasm src/contracts/token/soroban_token_spec.wasm \
  --id "$TOKEN_ID" \
  --fn xfer -- \
  --from "$TOKEN_ADMIN_ADDRESS" \
  --to "$DESTINATION_ADDRESS" \
  --amount "50000000" 

Here, src/contracts/token/soroban_token_spec.wasm is the path of token wasm file. We provide you the one used when wrapping the token.

6. Did it mint? in Stellar or in Classic?

How can we know if we in fact minted the token?

In fact, when we wrap the token, both balances of the token Soroban/Classic are shared. Hence, if we ask Stellar Classic it yould say that there are not 5 units anymore, but 10.

And if we ask to the SAC token, it should say the same.

In chapter 5 we took information about the Stellar Asset in the classic Stellar. Let's ask Stellar Classic (check chapter 5!)

docker exec soroban-preview-7 node src/getInfo.js

The answer:

Futurenet Classic Info: 
{
  _links: { toml: { href: '' } },
  asset_type: 'credit_alphanum12',
  asset_code: 'MYASSETCODE',
  asset_issuer: 'GAM5XOXRUWPMKENBGOEAKMLRQ4ENHLHDSU2L2J7TVJ34ZI7S6PHMYIGI',
  paging_token: 'MYASSETCODE_GAM5XOXRUWPMKENBGOEAKMLRQ4ENHLHDSU2L2J7TVJ34ZI7S6PHMYIGI_credit_alphanum12',
  num_accounts: 1,
  num_claimable_balances: 0,
  num_liquidity_pools: 0,
  amount: '10.0000000',
  accounts: {
    authorized: 1,
    authorized_to_maintain_liabilities: 0,
    unauthorized: 0
  },
  claimable_balances_amount: '0.0000000',
  liquidity_pools_amount: '0.0000000',
  balances: {
    authorized: '10.0000000',
    authorized_to_maintain_liabilities: '0.0000000',
    unauthorized: '0.0000000'
  },
  flags: {
    auth_required: false,
    auth_revocable: false,
    auth_immutable: false,
    auth_clawback_enabled: false
  },
  toml: [Function (anonymous)]
}

We have now 10 units of the token!
We managed to suscesfully mint a wrapped asset in Soroban!

5. Use our code

If you want to use our code in the Token Playground's Repo, you can just call our script with the soroban-preview-7 docker containter

You can run it by:

docker exec soroban-preview-7 ./src/mint_with_just_token_id.sh standalone using_docker

Check all the code of our mint_with_just_token_id.sh script here

What is next?

In this chapter we minted units in Soroban, but we checked the total balance in Classic. In the next chapter we will use the SAC contract to get information about the token in Soroban. We should get the same information than in classic. Why? Because balances are shared!

Are you ready?

This Playground has been developed by @esteblock in collaboration with @marcos74 from @Dogstarcoin