checkApproval

The checkApproval method checks if Symphony has sufficient allowance to spend tokens on behalf of the user. This check is necessary before executing swaps with non-native tokens.

Signature

async checkApproval(params?: {
  variable?: Route | string;
  signer?: Signer; // ethers/ethersV5
  walletClient?: WalletClient; // viem
  amount?: string | bigint;
  includesNative?: boolean;
  options?: {
    isRaw?: boolean;
  }
}): Promise<boolean>

TypeScript Types

// Import for viem
import type { Route } from "symphony-sdk/viem";
 
// Import for ethersV5
import type { Route } from "symphony-sdk/ethersV5";
 
// Import for ethers v6
import type { Route } from "symphony-sdk/ethers";

Parameters

• variable: Route object or token address (defaults to this.route)
• signer/walletClient: Transaction signer (defaults to Route's signer)
• amount: Amount to check approval for (defaults to route's input amount)
  • If isRaw=true: Amount in wei units
  • If isRaw=false: Amount in formatted units
• includesNative: Whether the swap includes native token (defaults to route's value)
• options: Configuration options
  • isRaw: If true, amount is in wei units (default: true)

Returns

Returns a Promise that resolves to:

• true: Symphony has sufficient allowance to execute the swap
• false: Symphony needs approval to execute the swap

Example Usage

const symphony = new Symphony();
 
// Get a route
const route = await symphony.getRoute(tokenIn, tokenOut, "1.0");
 
// Check if approval is needed
const isApproved = await route.checkApproval();
if (!isApproved) {
  // Request approval if needed
  const approvalTx = await route.giveApproval();
  console.log(`Approval transaction: ${approvalTx.transactionHash}`);
}
 
// Now we can swap
const { swapReceipt } = await route.swap();

TypeScript Example

import { Route } from "symphony-sdk/ethers";
import type { Route } from "symphony-sdk/ethers";
 
const route: Route = await symphony.getRoute(tokenIn, tokenOut, "1.0");
 
// Check approval with type safety
const isApproved: boolean = await route.checkApproval();
 
if (!isApproved) {
  const receipt = await route.giveApproval();
  console.log(`Approved at block ${receipt.blockNumber}`);
}

Custom Amount Check

// Check if a specific amount is approved
const hasEnoughAllowance = await route.checkApproval({
  amount: "100.0",
  options: { isRaw: false },
});
 
if (!hasEnoughAllowance) {
  // Approve the larger amount
  await route.giveApproval({
    amount: "100.0",
    options: { isRaw: false },
  });
}

Notes

• If the input token is the native token (e.g., SEI), checkApproval will always return true since native tokens don't require approval
• The method checks if the allowance is sufficient for the specific amount in the route
• A wallet client must be connected to check approval
• You can combine approval and swap in a single call using the swap method with skipApproval: false. See swap for details.

Error Handling

The method will throw an error if:

• No wallet client is connected
• The token address is invalid
• The token is not listed on Symphony
• The allowance check fails due to RPC issues