10 : Write the native token (XLM) using soroban-cli.

Token Playground Chapter 10 : Write the native token (XLM) contract using soroban-cli

• 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

What about when we want to use XLM inside a Soroban smart contract? How do we trigger those transactions? Can we trigger transactions on behalf the user using the require_auth method?

In this chapter we will see how to interact and write (call functions that change the state of the Blockchain) the native token (XLM) smart contract inside Soroban using soroban-cli.

Specifically we will call the transfer, approve and transfer_from functions:

2. Setting up our environment

Configure soroban-cli, wrap the native token (see chapter 8) and get its address:

NETWORK="standalone"
SOROBAN_RPC_HOST="http://stellar:8000"
SOROBAN_RPC_URL="$SOROBAN_RPC_HOST/soroban/rpc"
FRIENDBOT_URL="$SOROBAN_RPC_HOST/friendbot"
SOROBAN_NETWORK_PASSPHRASE="Standalone Network ; February 2017"

echo Adding network
soroban config network add "$NETWORK" \
  --rpc-url "$SOROBAN_RPC_URL" \
  --network-passphrase "$SOROBAN_NETWORK_PASSPHRASE"
echo ---

soroban config identity generate my-account
MY_ACCOUNT_ADDRESS="$(soroban config identity address my-account)"
curl  --silent -X POST "$FRIENDBOT_URL?addr=$MY_ACCOUNT_ADDRESS" > null
ARGS="--network standalone --source-account my-account"

echo Wrapping token
TOKEN_ADDRESS=$(soroban lab token wrap $ARGS --asset native)
echo Wrapped with address result: $TOKEN_ADDRESS
echo ---

echo Wrapping might fail if it was done before, so we are also getting the address:
TOKEN_ADDRESS="$(soroban lab token id --asset native --network standalone)"
echo Native token address: $TOKEN_ADDRESS
echo ---

3. Setting up your identities

In this chapter we will use a my-account, spender and recipient accounts. The my-account account will be the main account that will holds XLM and send them to the recipient. Also, the my-account will allow the spender to send XLM on his behalf:

echo Creating my-account identity
soroban config identity generate my-account
MY_ACCOUNT_ADDRESS="$(soroban config identity address my-account)"
curl  --silent -X POST "$FRIENDBOT_URL?addr=$MY_ACCOUNT_ADDRESS" > null

echo Creating spender identity
soroban config identity generate spender
SPENDER="$(soroban config identity address spender)"
curl  --silent -X POST "$FRIENDBOT_URL?addr=$SPENDER" > null

echo Creating recipient identity
soroban config identity generate recipient
RECIPIENT="$(soroban config identity address recipient)"
curl  --silent -X POST "$FRIENDBOT_URL?addr=$RECIPIENT" > null

4. Transfer XLM

1. Check the initial balance of the recipient

echo Checking initial balance of recipient
soroban contract invoke   --network standalone --source-account my-account  --id "$TOKEN_ADDRESS"   --   balance   --id $RECIPIENT

The result should be:

Checking initial balance of recipient
"100000000000"

1. Call the transfer function using my-account as source-account

echo Sending 5 stroops from my-account to recipient
soroban contract invoke   --network standalone --source-account my-account  --id "$TOKEN_ADDRESS"   --   transfer   --from $MY_ACCOUNT_ADDRESS   --to $RECIPIENT  --amount 5

1. Check the new balance of the recipient

echo Checking new balance of recipient
soroban contract invoke   --network standalone --source-account my-account  --id "$TOKEN_ADDRESS"   --   balance   --id $RECIPIENT

The result should be:

Checking new balance of recipient
"100000000005"

5. Using transfer_from

echo Approve 5 stroops from my-account. spender will be the spender identity
soroban contract invoke   --network standalone --source-account my-account  --id "$TOKEN_ADDRESS"   --   approve   --from $MY_ACCOUNT_ADDRESS   --spender $SPENDER  --amount 5 --expiration-ledger 999999 

echo Checkint the allowance of spender to spend from my-account
soroban contract invoke   --network standalone --source-account my-account  --id "$TOKEN_ADDRESS"   --   allowance   --from $MY_ACCOUNT_ADDRESS   --spender $SPENDER

echo Checking recipient balance before doing the transfer_from
soroban contract invoke   --network standalone --source-account my-account  --id "$TOKEN_ADDRESS"   --   balance   --id $RECIPIENT

echo Executing the transfer_from function. Spender is spending 5 stroops. Sending from my-account to recipient
soroban contract invoke   --network standalone --source-account spender  --id "$TOKEN_ADDRESS"   --   transfer_from   --spender $SPENDER --from $MY_ACCOUNT_ADDRESS --to $RECIPIENT  --amount 5

echo Checking new balance of recipient
soroban contract invoke   --network standalone --source-account my-account  --id "$TOKEN_ADDRESS"   --   balance   --id $RECIPIENT

The result should be:

Approve 5 stroops from my-account. spender will be the spender identity

Checkint the allowance of spender to spend from my-account
"5"
Checking recipient balance before doing the transfer_from
"100000000005"
Executing the transfer_from function. Spender is spending 5 stroops. Sending from my-account to recipient

Checking new balance of recipient
"100000000010"

6. 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-10 docker containter

You can run it by:

bash src/chapter10/sending_native_XLM_soroban.sh 

Check all the code in the repo!

What is next?

In this chapter we used the native token contract address in order to send some XLM using the transfer, aprove and transfer_from functions.

In the next chapter we'll use the native token inside our own written smart contract!

Are you ready?

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This Playground chapter has been written by @esteblock