Interact with a smart contract using Foundry

Prerequisites

You should already have a Foundry project set up, and have deployed your smart contract successfully. See the deploy a smart contract using Foundry tutorial for how to do so.

Optionally, but strongly recommended: You should also have successfully verified your smart contract. See the verify a smart contract using Foundry tutorial for how to do so.

Invoke function - query

Queries are read-only operations. So smart contract state is not updated. As no state change is needed, no wallets, signatures, or transaction fees (gas) are required.

Use the following command to query the value() function:

cast call \
  --rpc-url injectiveEvm \
  ${SC_ADDRESS} \
  "value()"

Replace ${SC_ADDRESS} with the address at which you deployed your smart contract.

For example, if the smart contract address is 0x213ba803265386c10ce04a2caa0f31ff3440b9cf, the command is:

cast call \
  --rpc-url injectiveEvm \
  0x213ba803265386c10ce04a2caa0f31ff3440b9cf \
  "value()"

This should output the following.

0x0000000000000000000000000000000000000000000000000000000000000000

Note that 0x0000000000000000000000000000000000000000000000000000000000000000 means 0. It is the raw representation in hexadecimal for Solidity’s uint256 (the return type of the value() function in the smart contract).

Invoke function - transaction

Transactions are write operations. So smart contract state is updated. As state change can occur, the transaction must be signed by a wallet, and transaction fees (gas) need to be paid.

Use the following command to transact the increment(num) function.

cast send \
  --legacy \
  --rpc-url injectiveEvm \
  --gas-price 160000000 \
  --gas-limit 2000000 \
  --account injTest \
  ${SC_ADDRESS} \
  "increment(uint256)" \
  1

Note that gas price is stated in wei. 1 wei = 10^-18 INJ.

Replace ${SC_ADDRESS} with the address at which you deployed your smart contract.

For example, if the smart contract address is 0x213ba803265386c10ce04a2caa0f31ff3440b9cf, the command is:

cast send \
  --legacy \
  --rpc-url injectiveEvm \
  --gas-price 160000000 \
  --gas-limit 2000000 \
  --account injTest \
  0x213ba803265386c10ce04a2caa0f31ff3440b9cf \
  "increment(uint256)" \
  1

If successful, this should produce a result similar to the following:

Enter keystore password:
blockHash            0xe4c1f5faafc5365c43678135d6adc87104f0e288cddfcdffeb2f5aa08282ca22
blockNumber          83078201
contractAddress
cumulativeGasUsed    43623
effectiveGasPrice    160000000
from                 0x58f936cb685Bd6a7dC9a21Fa83E8aaaF8EDD5724
gasUsed              43623
logs                 []
logsBloom            0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
root
status               1 (success)
transactionHash      0x3c95e15ba24074301323e09d09d5967cc2858e255d1fdfd912758fd8bbd353b4
transactionIndex     0
type                 0
blobGasPrice
blobGasUsed
to                   0x213bA803265386C10CE04a2cAa0f31FF3440b9cF

After updating the state, you can query the new state. The result will reflect the state change.

cast call \
  --rpc-url injectiveEvm \
  ${SC_ADDRESS} \
  "value()"

This time the result should be 0x0000000000000000000000000000000000000000000000000000000000000001 because 0 + 1 = 1.

0x0000000000000000000000000000000000000000000000000000000000000001

Next steps

Congratulations, you have completed this entire guide for developing EVM smart contracts on Injective using Foundry!

Smart contracts do not provide a user experience for non-technical users. To cater to them, you will need to build a decentralised application. To do so, check out the your first dApp guides!