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Prepare transaction data to approve vault shares for withdrawal via the WithdrawQueue contract.
Before withdrawing, you must approve the WithdrawQueue contract to spend your vault shares. Consider using prepareWithdrawalAuthorization for a higher-level API that handles approval checking automatically.

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Import

import { prepareApproveWithdrawOrderTxData } from "@paxoslabs/amplify-sdk";

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Usage

const txData = await prepareApproveWithdrawOrderTxData({
  yieldType: "CORE",
  wantAssetAddress: "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
  withdrawAmount: "100.0",
  chainId: 1,
});

// Execute approval
const hash = await walletClient.writeContract(txData);

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Parameters

ParameterTypeRequiredDescription
yieldTypeYieldTypeYesYield strategy (CORE, TREASURY, FRONTIER)
wantAssetAddressAddressYesToken address you want to receive
withdrawAmountstringNoAmount to approve (defaults to max uint256)
chainIdChainIdYesChain ID
shareDecimalsnumberNoPre-fetched vault share decimals (avoids redundant RPC call)

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Return Type

interface ApproveWithdrawOrderTxData {
  abi: typeof BoringVaultAbi;
  address: `0x${string}`;         // Vault shares (BoringVault) address
  functionName: "approve";
  args: [spender: `0x${string}`, amount: bigint];
}

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Examples

import { prepareApproveWithdrawOrderTxData } from "@paxoslabs/amplify-sdk";
import { createWalletClient, createPublicClient, http } from "viem";
import { mainnet } from "viem/chains";

async function approveWithdraw(userAddress: `0x${string}`) {
  const walletClient = createWalletClient({
    account: userAddress,
    chain: mainnet,
    transport: http(),
  });
  const publicClient = createPublicClient({
    chain: mainnet,
    transport: http(),
  });

  const USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";

  // Approve specific amount
  const txData = await prepareApproveWithdrawOrderTxData({
    yieldType: "CORE",
    wantAssetAddress: USDC,
    withdrawAmount: "100.0",
    chainId: 1,
  });

  const hash = await walletClient.writeContract(txData);
  const receipt = await publicClient.waitForTransactionReceipt({ hash });

  console.log("Approval confirmed:", receipt.transactionHash);
  return hash;
}

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Max vs Specific Approval

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Max Approval (Default)

When withdrawAmount is not provided, the SDK approves the maximum amount. This is a one-time approval that covers all future withdrawals: 
// Max approval - no amount specified
const txData = await prepareApproveWithdrawOrderTxData({
  yieldType: "CORE",
  wantAssetAddress: USDC_ADDRESS,
  chainId: 1,
});

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Specific Amount Approval

For tighter security, approve only the amount you intend to withdraw: 
// Approve exactly 100 shares
const txData = await prepareApproveWithdrawOrderTxData({
  yieldType: "CORE",
  wantAssetAddress: USDC_ADDRESS,
  withdrawAmount: "100.0",
  chainId: 1,
});

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Checking Existing Approval

Before approving, check if approval is already granted: 
import {
  isWithdrawalSpendApproved,
  prepareApproveWithdrawOrderTxData,
} from "@paxoslabs/amplify-sdk";

async function ensureApproval(userAddress: `0x${string}`) {
  const USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";

  const approvalInfo = await isWithdrawalSpendApproved({
    yieldType: "CORE",
    wantAssetAddress: USDC,
    recipientAddress: userAddress,
    chainId: 1,
  });

  if (approvalInfo.isApproved) {
    console.log(`Already approved. Allowance: ${approvalInfo.allowance}`);
    return null;
  }

  // Need to approve first
  return prepareApproveWithdrawOrderTxData({
    yieldType: "CORE",
    wantAssetAddress: USDC,
    chainId: 1,
  });
}
Consider using prepareWithdrawalAuthorization instead, which combines the approval check and approval preparation into a single call.

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Error Handling

ErrorDescriptionResolution
Vault chain mismatchVault not on requested chainVerify chainId matches vault deployment
BoringVault contract address not configuredMissing vault configCheck vault exists for yieldType/chain
WithdrawQueue contract address not configuredMissing queue configCheck vault configuration
import { prepareApproveWithdrawOrderTxData, APIError } from "@paxoslabs/amplify-sdk";

try {
  const txData = await prepareApproveWithdrawOrderTxData({
    yieldType: "CORE",
    wantAssetAddress: USDC_ADDRESS,
    chainId: 1,
  });
} catch (error) {
  if (error instanceof APIError) {
    console.error("SDK Error:", error.message);
  }
}