Your First Smart Contract

• You can find the chain details on the EVM Developers page

• You can find an example of a simple Counter contract and deployment instructions within the injective-foundry-example.

• You can also read our general-purpose Testnet Deployment guides.

Building and deploying smart contracts on Injective is straightforward. As your first example, we'll take a look at a simple Counter smart contract example.

1. We'll develop the smart contract,

2. Deploy to the Injective EVM Testnet following the steps in Testnet Deployment,

3. Query the smart contract using cast,

4. Send a transaction to change the smart contract state using cast,

Requirements

You will need a wallet, and an account that has been funded with some Testnet INJ. After creating your account, be sure to copy your private key somewhere accessible, as you will need it to complete this tutorial.

You can request EVM testnet funds from the official Testnet faucet here.

1. The guide uses foundry for deployments. Install it by running:

curl -L https://foundry.paradigm.xyz | bash

To verify the installation:

forge --version

Note that the version used in this tutorial was 1.2.3-stable. Be sure to use this version or later when following along.

1. Add Injective EVM to your foundry.toml

If you are starting a new project from scratch:

• Create a new directory for the project

• Create a new foundry.toml file inside it

• Create an src subdirectory

mkdir my-first-smart-contract-inj
cd my-first-smart-contract-inj
touch foundry.toml
mkdir src

[rpc_endpoints]
injectiveEvm = "https://k8s.testnet.json-rpc.injective.network/"

Development

We can build a simple Counter example and then do a transaction/query the smart contract state.

Smart Contract Code

Next, create a simple Counter smart contract written in Solidity.

touch src/counter.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.27;

contract Counter {
    uint256 public number;

    event ValueSet(address indexed sender, uint256 newValue);
    event UserRevert(address indexed sender, string reason);

    function setNumber(uint256 newNumber) public {
        number = newNumber;
        emit ValueSet(msg.sender, number);
    }

    function increment() public {
        number++;
        emit ValueSet(msg.sender, number);
    }

    function userRevert(string memory reason) public {
        emit UserRevert(msg.sender, reason);
        revert("user requested a revert; see event for details");
    }
}

Deployment

Read more about Testnet Deployment.

Querying the Smart Contract

Using Injective

// WiP

Using Foundry

Let's query the smart contract state using cast.

First use cast sig:

cast sig "function number() returns (uint256)"

This should produce the following output, which is the function signature:

0x8381f58a

We use this function signature in cast call, which performs the actual query:

cast call \
  --rpc-url injectiveEvm \
  {SmartContractAddress} \
  0x8381f58a

This outputs the return value of invoking number() on your deployed smart contract.

If you have yet to perform any transactions on this smart contract, it should show 0.

Transactions against the Smart Contract

Using Injective

// WiP

Using Foundry

Let's make a transaction and change the smart contract state using cast.

First use cast sig, this time on a different function:

cast sig "function increment()"

This should produce a different function signature from before, as points to a different function:

0xd09de08a

We use this cast send, which performs the actual transaction:

cast send \
  --legacy \
  --rpc-url injectiveEvm \
  --private-key {YourPrivateKey} \
  {SmartContractAddress} \
  0xd09de08a

If you visit the smart contract address in a block explorer, you should see the new transaction registered against it.

If you repeat the cast call command above, which invokes number(), you should get an updated value of 1 this time.

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