redeem

params of yAssetParams -> (list(op), storage upd)

Redeem user collateral locked under yToken token of tokenId, burning amount of users yTokens.

The yToken contract expects that underlying token info of tokenId and all borrowed by user before tokenIds are updated by calling PriceFeed.getPrice and updateInterest in the same block before this contract method

If amount passed 0n than amount calculated as

amount = userBalance * token.liquidity / token.totalSupply

Types

type yAssetParams       is [@layout:comb] record [
  tokenId                 : nat; // yToken token Id
  amount                  : nat; // amount tokens to burn
]

Parameter	Type	Description
tokenId	nat	yToken identifier
amount	nat	amount of yTokens to burn

Usage

🌮 Taquito

const redeemTokenId = 0; // or new BigNumber(0) or "0"
const amount = 10_000_000; // amount of yTokens to burn, pass 0 to burn all.
const yupana = await tezos.contract.at(yTokenAddress);
const proxy = await tezos.contract.at(proxyAddress);
const borrowedTokenIds = [1, 2]; // user borrowed tokens
const updBorrowed = borrowedTokenIds.reduce(
  (batch, tokenId) => {
    batch.push({
        kind: "transaction",
        ...yupana.methods.updateInterest(tokenId).toTransferParams(),
      },
      {
        kind: "transaction",
        ...proxy.methods.getPrice([tokenId]).toTransferParams(),
      });
      return batch;
    }
const batchArray = [
      ...updBorrowed,
      {
        kind: "transaction",
        ...yupana.methods.updateInterest(redeemTokenId).toTransferParams(),
      },
      {
        kind: "transaction",
        ...proxy.methods.getPrice([redeemTokenId]).toTransferParams(),
      },
      {
        kind: "transaction",
        ...yupana.methods.redeem(redeemTokenId, amount).toTransferParams(),
      },
    ];
const batch = await tezos.wallet.batch(batchArray);
const operation = await batch.send();
await operation.confirmation();

🐍 Pytezos

Errors

burnAmount = amount * token.totalSupply / token.liquidity

• yToken/not-enough-tokens-to-burn - not enough balance of tokens to burn burnAmount wanted by user.

• underflow/totalSupplyF - total supply less than burnAmount.

• underflow/totalLiquidF - total liquidity less than amount.

• token/cant-get-contract-token - FA12 token contract address does not contain transfer entrypoint from FA12 interface.

• token/cant-get-contract-fa2-token - FA2 token contract address does not contain transfer entrypoint from FA2 interface.

• yToken/exceeds-allowable-redeem - raised when outstanding borrow value greater than max collateral value.

• underflow/liquidity - reserves - liquidity more than reserves.

• ceil-div-error - division of two numbers fails.

• yToken/need-update - token price and interest not updated (see warning above)

• yToken/yToken-undefined - token identifier is not assigned to any known yTokens.