Interacting with contracts

Eclair provides a simple way to interact with smart contracts using familiar Solidity syntax.

Calling contracts and sending transactions

For any contract loaded, all the functions of the contract defined in its ABI are available as methods on the contract object.

By default, calling a view function will call it and return the result, while calling a non-view function will send a transaction and returns the transaction hash. Sending a transaction requires an account to be loaded.

The behavior can be changed by using one of the following method on the returned function object:

call: Call the function and return the result
traceCall: Same as call but also prints the trace of the call (also potentially shows better error messages)
send: Sends a transaction to the function and return the result
encode: ABI-encodes the function call

>> dai = repl.fetchAbi("DAI", 0x6B175474E89094C44Da98b954EedeAC495271d0F)
>> dai.balanceOf(0x4DEDf26112B3Ec8eC46e7E31EA5e123490B05B8B)
49984400000000000000000000
>> repl.loadPrivateKey()
>> dai.balanceOf.send(0x4DEDf26112B3Ec8eC46e7E31EA5e123490B05B8B)
Transaction(0x6a2f1b956769d06257475d18ceeec9ee9487d91c97d36346a3cc84d568e36e5c)
>> dai.balanceOf.encode(0x4DEDf26112B3Ec8eC46e7E31EA5e123490B05B8B)
0x70a082310000000000000000000000004dedf26112b3ec8ec46e7e31ea5e123490b05b8b
>> dai.transfer(0x4DEDf26112B3Ec8eC46e7E31EA5e123490B05B8B, 1e18)
Transaction(0xf3e85039345ff864bb216b10e84c7d009e99ec55b370dae22706b0d48ea41583)

Transaction options

There are different options available when calling and sending transactions to contracts. The options can be passed using the {key: value} Solidity syntax, for example:

>> tx = weth.deposit{value: 1e18}()

The following options are currently supported:

value: sets the msg.value of the transaction
block: sets the block number to execute the call on (only works for calls, not for sending transactions)
from: sets the from for the call (only works for calls, not for sending transactions)
gasLimit: sets the gas limit to use for the transaction
maxFee: sets the maximum fee to pay for the transaction
priorityFee: sets the priority fee to pay for the transaction
gasPrice: sets gas price to use for the (legacy) transaction

Transaction receipts

After sending a transaction, you can get the transaction receipt using the Transaction.getReceipt method.

>> tx = dai.approve(0x83F20F44975D03b1b09e64809B757c47f942BEeA, 1e18)
>> tx.getReceipt()
TransactionReceipt { tx_hash: 0x248ad948d1e4eefc6ccb271cac2001ebbdb2346beddc7656b1f9518f216c8b02, block_hash: 0x688517fe5e540b4e3953ed3ba84cc4d70903ddffb981a66c51ca49ca13c90bb1, block_number: 20380613, status: true, gas_used: 46146, gas_price: 4547819249 }
>> _.logs
[Log { address: 0x6B175474E89094C44Da98b954EedeAC495271d0F, topics: [0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925, 0x000000000000000000000000f39fd6e51aad88f6f4ce6ab8827279cfffb92266, 0x00000000000000000000000083f20f44975d03b1b09e64809b757c47f942beea], data: 0x0000000000000000000000000000000000000000000000000de0b6b3a7640000 }]

If the ABI of the contract emitting the log is loaded, the logs will automatically be decoded and the decoded arguments will be available in the args property of each log.

Events

Eclair provides a way to fetch events emitted by a contract using the events.fetch method.

>> events.fetch{fromBlock: 20490506, toBlock: 20490512}(0xe07F9D810a48ab5c3c914BA3cA53AF14E4491e8A)[0]
Log { address: 0xe07F9D810a48ab5c3c914BA3cA53AF14E4491e8A, topics: [0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef, 0x000000000000000000000000ba12222222228d8ba445958a75a0704d566bf2c8, 0x000000000000000000000000f081470f5c6fbccf48cc4e5b82dd926409dcdd67], data: 0x00000000000000000000000000000000000000000000000e8bd6d724bc4c7886, args: Transfer { from: 0xBA12222222228d8Ba445958a75a0704d566BF2C8, to: 0xf081470f5C6FBCCF48cC4e5B82Dd926409DcdD67, value: 268330894800999708806 } }

The events.fetch accepts either a single address or a list of addresses as the first argument, as well as some options to filter the logs returned. It returns a list of logs that match the given criteria, and automatically decodes each log if the ABI is loaded.

Options

The events.fetch method accepts the following options:

fromBlock: the block number to start fetching events from
toBlock: the block number to stop fetching events at
topic0: topic0 of the event
topic1: topic1 of the event
topic2: topic2 of the event
topic3: topic3 of the event

By default, it will try to fetch from the first ever block to the latest block. In many cases, the RPC provider will reject the request because too much data would be returned, in which case options above will need to be added to restrict the size of the response.

To only get one type of event, e.g. Transfer, you can filter using topic0 and the selector of the desired event.