Deploying A Smart Contract

Before You Begin
This tutorial expects you to be familiar with Metamask. You can learn about Metamask in the following tutorials:
Introduction to Metamask
Creating a Wallet
Introduction to Metamask
Switch Networks

We’re going to be creating an ERC-20 token in this quickstart. The ERC-20 contract is used a lot in representing a massive array of tokens across multiple blockchains, primarily the Ethereum blockchain.

Prerequisites

  • You must have a Metamask wallet ready to use in your browser. Learn how here.
  • You must be connected to the Filecoin Wallaby Testnet. Learn how here.

Instructions

Get some funds

Before you can operate in the Filecoin test network, you need funds to pay for gas fees.

  1. Open your browser and open MetaMask.

  2. Click your account to copy the address to your clipboard:

    Select your account in MetaMask.

  3. Go to wallaby.network and scrolldown to the Faucet section.

  4. Paste your address into the address field, complete the I am human captcha, and then click Send:

    Click the send button in MetaMask.

  5. The faucet should give you a link to the transaction. Click it to view your transaction:

    Click the transaction link on the faucet.

  6. The block explorer will show you the transaction history for your address. After a couple of minutes, you should see 5000 tFIL transferred to your address.

  7. Open MetaMask to confirm that you received the tFIL:

    View your funds in MetaMask.

That’s all there is to it! Getting tFil is easy!

Contract creation

The development environment we’re going to be using is called Remix, viewable at remix.ethereum.org. Remix is an incredibly sophisticated tool, and there’s a lot you can play around with! In this tutorial however, we’re going to stick to the very basics. If you want to learn more, check out the Remix documentation.

Create a workspace

In Remix, workspaces are siloed environments where you can create a contract, or group of contracts, for each project. Let’s create a new workspace to create our new ERC-20 token.

  1. Open remix.ethereum.org.

  2. Click the + icon next to Workspaces to create a new workspace:

    Create a new Remix workspace.

  3. In the Choose a template dropdown, select ERC 20.

  4. Select the Mintable checkbox.

  5. Enter a fun name for your token in the Workspace name field. Something like CorgiCoin works fine.

    Name your workspace in Remix.

  6. Click OK to create your new workspace.

Customize the contract

The contract template we’re using is pretty simple; we just need to modify a couple of variables.

  1. Under the contract directory, click MyToken.sol.

  2. In the editor panel, replace MyToken with whatever you’d like to name your token. In this example, we’ll use CorgiCoin.

  3. On the same line, replace the second string with whatever you want the symbol of your token to be. In this example, we’ll use CRG.

    Edit your contract in Remix.

That’s all we need to change within this contract. You can see on line 4 that this contract is importing another contract from @openzeppelin for us, meaning that we can keep our custom token contract simple.

Compile

  1. Click the green play symbol at the top of the workspace to compile your contract. You can also press CMD + s on MacOS or CTRL + s on Linux and Windows.
  2. Remix automatically fetches the two import contracts from the top of our .sol contract. You can see these imported contracts under the .deps directory. You can browse the contracts there, but Remix will not save any changes you make.

Remix showing imported contracts.

Deploy

Now that we’ve successfully compiled our contract, we need to deploy it somewhere! This is where our previous MetaMask setup comes into play.

  1. Click the Deploy tab from the left.

    Click deploy within Remix.

  2. Under the Environment dropdown, select Injected Provider - MetaMask.

    Select the proper network within Remix.

  3. MetaMask will open a new window confirming that you want to connect your account to Remix.

  4. Click Next and then Connect to connect your tFIL account to Remix.

  5. Back in Remix, under the Account field, you’ll see that it says something like 0x5A5... (5000 ether). This value is 5000 tFIL, but Remix doesn’t natively support the Filecoin network and thus doesn’t understand what tFIL is. This isn’t a problem; it’s just a little quirk of using Remix.

    Remix showing 5000 tFil.

  6. Under the Contract dropdown, ensure the contract you created is selected.

    Select your contract in Remix.

  7. Click Deploy.

    Remix showing the deploy button.

  8. MetaMask will open a window and as you to confirm the transaction. Scroll down and click Confirm to have MetaMask deploy the contract.

  9. Back in Remix, a message at the bottom of the screen shows that the creation of your token is pending.

    A pending transaction in Remix.

  10. Wait around 90 seconds for the deployment to complete.

On the Filecoin network, a new set of blocks, also called a tipset, is created every thirty seconds. When deploying a contract, the transaction needs to be received by the network, and then the network needs to confirm the contract. This process takes around one to two tipsets to process – or around 60 to 90 seconds.

Use your contract

Now that we’ve compiled and deployed the contract, it’s time to actually interact with it!

Mint your tokens

Let’s call a method within the deployed contract to mint some tokens.

  1. Back in Remix, open the Deployed Contracts dropdown, within the Deploy sidebar tab.

    Remix showing my deployed contracts.

  2. Expand the mint method. You must fill in two fields here: to and amount.

    Remix showing the mint method of a contract.

  3. The to field specifies what address you want these initial tokens sent to. Open MetaMask, copy your address, and paste it into this field.

    Add an address into Remix.

  4. This field expects an attoFil value. 1 FIL is equal to 1,000,000,000,000,000,000 attoFil. So if you wanted to mint 100 FIL, you would enter 100 followed by 18 zeros: 100000000000000000000.

    Enter a value into Remix.

  5. Click Transact.

    Click transact in Remix.

  6. MetaMask will open a window and ask you to confirm the transaction. Again, you must wait for the network to process the transaction, which should take about 90 seconds. You can move on to the next section while you’re waiting.

    Remix pending the minting of a contract.

Add to MetaMask

Currently, MetaMask has no idea what our token is or what it even does. We can fix this by explicitly telling MetaMask the address of our contract.

  1. Go back to Remix and open the Deploy sidebar tab.

  2. Under Deployed Contracts, you should see your contract address at the top. Click the copy icon to copy the address to your clipboard.

    Copy your contract’s deployment address.

  3. Open MetaMask, select Assets, and click Import your tokens:

    Importing tokens into MetaMask.

  4. In the Token contract address field, paste the contract address you just copied from Remix and then click Add custom token. MetaMask should autofill the rest of the information based on what it can find from the Filecoin network.

    Import your tokens into MataMask.

  5. Click Import token.

    Click the import token button in MetaMask.

  6. You should now be able to see that you have 100 of your tokens within your MetaMask wallet!

    Final token import page in MetaMask.

Share your tokens

Having a bunch of tokens in your personal MetaMask is nice, but why not send some tokens to a friend? Your friend needs to create a wallet in MetaMask as we did in the Create a wallet and Switch networks tutorials. They will also need to import your contract deployment address like you did in the Add your tokens to MetaMask section. Remember, you need to pay gas for every transaction that you make! If your friend tries to send some of your tokens to someone else but can’t, it might be because they don’t have any tFil.

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