Struct ethers_contract::Multicall [−][src]
pub struct Multicall<M> { /* fields omitted */ }
Expand description
A Multicall is an abstraction for sending batched calls/transactions to the Ethereum blockchain.
It stores an instance of the Multicall
smart contract
and the user provided list of transactions to be made.
Multicall
can instantiate the Multicall contract instance from the chain ID of the client
supplied to new
. It supports the Ethereum mainnet, as well as testnets
Rinkeby,
Goerli and
Kovan.
Additionally, the block
number can be provided for the call by using the block
method.
Build on the Multicall
instance by adding calls using the add_call
method.
Example
use ethers_core::{
abi::Abi,
types::{Address, H256, U256},
};
use ethers_contract::{Contract, Multicall};
use ethers_providers::{Middleware, Http, Provider, PendingTransaction};
use std::{convert::TryFrom, sync::Arc};
// this is a dummy address used for illustration purpose
let address = "eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee".parse::<Address>()?;
// (ugly way to write the ABI inline, you can otherwise read it from a file)
let abi: Abi = serde_json::from_str(r#"[{"inputs":[{"internalType":"string","name":"value","type":"string"}],"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"author","type":"address"},{"indexed":true,"internalType":"address","name":"oldAuthor","type":"address"},{"indexed":false,"internalType":"string","name":"oldValue","type":"string"},{"indexed":false,"internalType":"string","name":"newValue","type":"string"}],"name":"ValueChanged","type":"event"},{"inputs":[],"name":"getValue","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"lastSender","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"string","name":"value","type":"string"}],"name":"setValue","outputs":[],"stateMutability":"nonpayable","type":"function"}]"#)?;
// connect to the network
let client = Provider::<Http>::try_from("https://kovan.infura.io/v3/c60b0bb42f8a4c6481ecd229eddaca27")?;
// create the contract object. This will be used to construct the calls for multicall
let client = Arc::new(client);
let contract = Contract::<Provider<Http>>::new(address, abi, Arc::clone(&client));
// note that these [`ContractCall`]s are futures, and need to be `.await`ed to resolve.
// But we will let `Multicall` to take care of that for us
let first_call = contract.method::<_, String>("getValue", ())?;
let second_call = contract.method::<_, Address>("lastSender", ())?;
// since this example connects to the Kovan testnet, we need not provide an address for
// the Multicall contract and we set that to `None`. If you wish to provide the address
// for the Multicall contract, you can pass the `Some(multicall_addr)` argument.
// Construction of the `Multicall` instance follows the builder pattern
let mut multicall = Multicall::new(Arc::clone(&client), None).await?;
multicall
.add_call(first_call)
.add_call(second_call);
// `await`ing on the `call` method lets us fetch the return values of both the above calls
// in one single RPC call
let _return_data: (String, Address) = multicall.call().await?;
// the same `Multicall` instance can be re-used to do a different batch of transactions.
// Say we wish to broadcast (send) a couple of transactions via the Multicall contract.
let first_broadcast = contract.method::<_, H256>("setValue", "some value".to_owned())?;
let second_broadcast = contract.method::<_, H256>("setValue", "new value".to_owned())?;
let multicall = multicall
.clear_calls()
.add_call(first_broadcast)
.add_call(second_broadcast);
// `await`ing the `send` method waits for the transaction to be broadcast, which also
// returns the transaction hash
let tx_hash = multicall.send().await?;
let _tx_receipt = PendingTransaction::new(tx_hash, &client).await?;
// you can also query ETH balances of multiple addresses
let address_1 = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa".parse::<Address>()?;
let address_2 = "ffffffffffffffffffffffffffffffffffffffff".parse::<Address>()?;
let multicall = multicall
.clear_calls()
.eth_balance_of(address_1)
.eth_balance_of(address_2);
let _balances: (U256, U256) = multicall.call().await?;
Implementations
Creates a new Multicall instance from the provided client. If provided with an address
,
it instantiates the Multicall contract with that address. Otherwise it fetches the address
from the address book.
Panics
If a None
address is provided, and the provided client also does not belong to one of
the supported network IDs (mainnet, kovan, rinkeby and goerli)
Sets the block
field for the multicall aggregate call
Appends a call
to the list of calls for the Multicall instance
Panics
If more than the maximum number of supported calls are added. The maximum limits is constrained due to tokenization/detokenization support for tuples
Appends a call
to the list of calls for the Multicall instance for querying
the ETH balance of an address
Panics
If more than the maximum number of supported calls are added. The maximum limits is constrained due to tokenization/detokenization support for tuples
Clear the batch of calls from the Multicall instance. Re-use the already instantiated Multicall, to send a different batch of transactions or do another aggregate query
let mut multicall = Multicall::new(client, None).await?;
multicall
.add_call(broadcast_1)
.add_call(broadcast_2);
let _tx_hash = multicall.send().await?;
multicall
.clear_calls()
.add_call(call_1)
.add_call(call_2);
let return_data: (String, Address) = multicall.call().await?;
Queries the Ethereum blockchain via an eth_call
, but via the Multicall contract.
It returns a ContractError<M>
if there is any error in the RPC call or while
detokenizing the tokens back to the expected return type. The return type must be
annonated while calling this method.
// If the Solidity function calls has the following return types:
// 1. `returns (uint256)`
// 2. `returns (string, address)`
// 3. `returns (bool)`
let result: (U256, (String, Address), bool) = multicall.call().await?;
Note: this method does not send a transaction from your account
Signs and broadcasts a batch of transactions by using the Multicall contract as proxy.
let tx_hash = multicall.send().await?;
Note: this method sends a transaction from your account, and will return an error if you do not have sufficient funds to pay for gas
Trait Implementations
Auto Trait Implementations
impl<M> RefUnwindSafe for Multicall<M> where
M: RefUnwindSafe,
impl<M> UnwindSafe for Multicall<M> where
M: RefUnwindSafe,
Blanket Implementations
Mutably borrows from an owned value. Read more
Instruments this type with the provided Span
, returning an
Instrumented
wrapper. Read more
Attaches the provided Subscriber
to this type, returning a
WithDispatch
wrapper. Read more
Attaches the current default Subscriber
to this type, returning a
WithDispatch
wrapper. Read more