Creating Ethereum Smart Contracts via Command Line – QuikNode –

Now let’s compile our project.

First, run sbt inside your eth-timelock directory:

$ sbt
[info] Loading settings for project eth-timelock from build.sbt ...
[info] Set current project to eth-timelock (in build file:/Users/testuser/eth-timelock/)
[info] Updating available solidity compiler set.
[info] sbt-ethereum-0.1.7-SNAPSHOT successfully initialized (built Sun, 17 Feb 2019 21:58:11 -0800)

Next run compile :

sbt:eth-timelock> compile
[info] Compiling 1 Solidity source to /Users/testuser/eth-timelock/target/ethereum/solidity...
[info] Compiling 'Timelock.sol'. (Debug source: '/Users/testuser/eth-timelock/target/ethereum/solidity/Timelock.sol')
[info] No Scala stubs will be generated as the setting 'ethcfgScalaStubsPackage' has not ben set.
[info] If you'd like Scala stubs to be generated, please define 'ethcfgScalaStubsPackage'.
[info] Updating ...
[info] Done updating.
[success] Total time: 1 s, completed Feb 25, 2019 12:16:01 AM

If you see any warning, just ignore it. You can see ABI get created under /target/ethereum/solidity .

Now we are ready to deploy our Smart Contract. But before that, if you want to switch the network, you can like this:

First, check your network with ethNodeChainIdPrint . sbt-etherum has MainNet set by default. Let’s change it to Ropsten (if you want some other testnet, feel free to do so too).

ethNodeChainIdOverrideSet 3

Here, 3 is the Ropsten network id. Remember, you should have a bit of ETH in your account to deploy the contract.

Now let’s start deploying:

sbt:eth-timelock> ethTransactionDeploy Timelock <TAB>

Always use Tab, sbt-ethereum has very rich Tab support for command completion. When you press Tab, it will tell you what to do next.

Our Smart Contract will need two parameters:

days — The number of days when the owner will be able to withdraw Ether.

seconds — Number of seconds when the owner will be able to withdraw Ether.

We’ll need the Smart Contract’s compute time using days + seconds, so let’s pass 0 days and 300 seconds (5 minutes):

ethTransactionDeploy Timelock 0 300 <TAB>

Now we need to pass the Ether amount, which will lock the contract for the given time. You can pass ETH amount using wei, gwei, szabo, finney, or ether units.

Let’s lock 10 wei for 5 minutes (300 seconds):

ethTransactionDeploy Timelock 0 300 10 wei

This will ask you to unlock your wallet using your passphrase and then ask you to submit the transaction. It will also ask to provide an alias name for your deployed contract.

Once done, it will give you deployed contract address which you can see on Etherscan. Let check the balance of the contract using:

ethAddressBalance timelock

Here timelock is alias name which we used while deploying our contract.

Interacting with your Smart Contract

Now, before 5 minutes runs out, let’s mock-test our Smart Contract using ethTransactionMock. This simulates a transaction on our Ethereum Node, but does not actually execute the transaction. So let’s try that:

sbt:eth-timelock> ethTransactionMock timelock withdraw

If you execute this within 5 minutes of deploying the Smart Contract, you will see an error. Execute the above command after 5 minutes and you will see a success message, but it does not run the command actually.

Now let’s actually withdraw our 10 wei from the contract after 5 minutes using:

ethTransactionInvoke timelock withdraw

This will create a transaction and withdraw the locked 10 wei. Once this command succeeds, you can check the balance of the contract again:

ethAddressBalance timelock

Conclusion

That’s it for today! Now you have another way to #buidl and deploy Smart Contracts. Let us know if you liked the article in the comment section and if you want to see more on this (or similar) topic 🙏

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