AToken
aTokens are tokens minted and burnt upon supply and withdraw of assets to an Aave market, which denote the amount of crypto assets supplied and the yield earned on those assets. The aTokens’ value is pegged to the value of the corresponding supplied asset at a 1:1 ratio and can be safely stored, transferred or traded. All yield collected by the aTokens' reserves are distributed to aToken holders directly by continuously increasing their wallet balance.
All standard EIP20 methods are implemented for aTokens, such as
balanceOf, transfer, transferFrom, approve, totalSupply etc.💡 `balanceOf` will always return the most up to date balance of the user, which includes their principal balance + the yield generated by the principal balance.
function DOMAIN_SEPARATOR()Get the domain separator for the token at current chain.
function nonces(address owner)Returns the nonce value for address specified as parameter. This is the nonce used when calling
permit()const token = new Contract(aTokenAddress, aToken.abi, provider);
await token.nonces(user);
function scaledBalanceOf(address user)Returns the scaled supply balance of
user. The scaled balance is the sum of all the updated stored balance divided by the reserve's liquidity index at the moment of the update.function getScaledUserBalanceAndSupply(address user)Returns the scaled balance of the user and the scaled total supply.
function scaledTotalSupply()Returns the scaled total supply of the aToken.
function getPreviousIndex(address user)Returns last index interest that was accrued to the user's balance (expressed in ray).
function getIncentivesController()Returns the address of the Incentives Controller contract
function POOL()Returns the address of the associated Pool for the aToken.
function UNDERLYING_ASSET_ADDRESS()Returns address of the underlying reserve asset.
function RESERVE_TREASURY_ADDRESS()Returns address of the Aave Treasury, controlled by governance, receiving the fee on this aToken.
function setIncentivesController(IAaveIncentivesController controller)Sets a new Incentives Controller.
Only Pool Admin can call this methods. To update Incentives Controller on main Aave market, Governance Proposal must be submitted.
Allows a user to permit another account (or contract) to use their funds using a signed message. This enables gas-less transactions and single approval/transfer transactions.
Parameter | Type | Description |
|---|---|---|
owner | address | The owner of the funds |
spender | address | The spender for the funds |
value | uint256 | The amount the spender is permitted to use |
deadline | uint256 | The deadline timestamp that the permit is valid. Use type(uint).max for no deadline. |
v | uint8 | Signature parameter |
r | bytes32 | Signature parameter |
s | bytes32 | Signature parameter |
import { signTypedData_v4 } from 'eth-sig-util'
import { fromRpcSig } from 'ethereumjs-util'
// ... other imports
import aTokenAbi from "./aTokenAbi.json"
// ... setup your web3 provider
const aTokenAddress = "ATOKEN_ADDRESS"
const aTokenContract = new web3.eth.Contract(aTokenAbi, aTokenAddress)
const privateKey = "YOUR_PRIVATE_KEY_WITHOUT_0x"
const chainId = 1
const owner = "OWNER_ADDRESS"
const spender = "SPENDER_ADDRESS"
const value = 100 // Amount the spender is permitted
const nonce = 1 // The next valid nonce, use `_nonces()`
const deadline = 1600093162
const permitParams = {
types: {
EIP712Domain: [
{ name: "name", type: "string" },
{ name: "version", type: "string" },
{ name: "chainId", type: "uint256" },
{ name: "verifyingContract", type: "address" },
],
Permit: [
{ name: "owner", type: "address" },
{ name: "spender", type: "address" },
{ name: "value", type: "uint256" },
{ name: "nonce", type: "uint256" },
{ name: "deadline", type: "uint256" },
],
},
primaryType: "Permit",
domain: {
name: "aTOKEN_NAME",
version: "1",
chainId: chainId,
verifyingContract: aTokenAddress,
},
message: {
owner,
spender,
value,
nonce,
deadline,
},
}
const signature = signTypedData_v4(
Buffer.from(privateKey, "hex"),
{ data: permitParams }
)
// The signature can now be used to execute the transaction
const { v, r, s } = fromRpcSig(signature)
await aTokenContract.methods
.permit({
owner,
spender,
value,
deadline,
v,
r,
s
})
.send()
.catch((e) => {
throw Error(`Error permitting: ${e.message}`)
})
- How aToken earn interest? / How aToken balance increases?LendingPool methods (deposit, withdraw, borrow, repay, liquidationCall) updates the state and cumulated liquidity index of the reserve once every block. AToken's
balanceOfmethod returns the balance computed based onblock.timestampandliquidityIndexof the underlying reserve and hence, returns the most up to date balance of account, which includesprincipal + interest. - LiquidityRate vs LiquidityIndex
- Can I transfer aTokens?Yes! with few caveat to keep in mind
- By transferring aTokens, you’re transferring your balance of the underlying asset. Only the account holding the aTokens can
withdrawthe deposited asset. - AToken transfer will fail if the resulting Health Factor of
userwill end up being below 1.
- If I transfer aToken does my pending liquidity rewards get transferred?No, liquidity rewards earned prior to the transfer of aToken are accrued by the user/address holding the aTokens originally. Though, all future liquidity rewards will be earned by the new recipient.
- What is the difference between ScaledBalance and Balance?
- Example please!Let’s say you supply 1,000 DAI to the Aave LendingPool, you will receive 1,000 aDAI (at 1:1 exchange rate).You can see your aDAI balance increasing right away.Now, say a month later your aDAI balance is 1,050. You could withdraw 1,050 DAI from LendingPool by burning 1050 aDAI.
Last modified 4mo ago