Viem Adapter
The Viem Adapter provides integration with the viem library, enabling you to use all CoW Protocol SDK packages with viem clients and accounts.
Installation
npm install @cowprotocol/sdk-viem-adapter
Constructor
import { ViemAdapter } from '@cowprotocol/sdk-viem-adapter'
import { http, createPublicClient, privateKeyToAccount } from 'viem'
import { sepolia } from 'viem/chains'
const account = privateKeyToAccount('YOUR_PRIVATE_KEY' as `0x${string}`)
const transport = http('YOUR_RPC_URL')
const provider = createPublicClient({ chain: sepolia, transport })
const adapter = new ViemAdapter({ provider, signer: account })
Parameters
A viem PublicClient instance created with createPublicClient.
Optional viem account instance or private key string. Can be created with privateKeyToAccount or obtained from wagmi hooks.
Optional WalletClient instance. Use this instead of signer when working with wagmi’s useWalletClient hook.
Properties
signer
Returns the ViemSignerAdapter instance. Throws an error if no signer was provided.
const signerAdapter = adapter.signer
utils
Utility methods for working with viem types and contracts.
const interface = adapter.utils.createInterface(abi)
TypedDataVersionedSigner
Signer class for EIP-712 typed data with version support.
TypedDataV3Signer
Signer class for EIP-712 typed data version 3 (legacy).
IntChainIdTypedDataV4Signer
Signer class for EIP-712 typed data version 4 with integer chain ID handling.
Methods
getChainId
Returns the chain ID from the connected provider.
const chainId = await adapter.getChainId()
Promise<number>
getCode
Returns the bytecode at a given address.
const code = await adapter.getCode('0x...')
address (string): The contract address
Returns: Promise<string | undefined>
getTransactionReceipt
Returns the transaction receipt for a given transaction hash.
const receipt = await adapter.getTransactionReceipt('0x...')
hash (string): The transaction hash
Returns: Promise<TransactionReceipt | null>
getStorageAt
Returns the value from a storage position at a given address.
const value = await adapter.getStorageAt('0x...', '0x0')
address (Address): The contract addressslot (0x${string}): The storage slot
Returns: Promise<0x${string}>
call
Executes a read-only call to a contract.
const result = await adapter.call({
to: '0x...',
data: '0x...'
})
txParams (TransactionParams): Transaction parametersprovider (PublicClient, optional): Override provider
Returns: Promise<string>
readContract
Reads from a contract function.
const result = await adapter.readContract({
address: '0x...',
abi: contractAbi,
functionName: 'balanceOf',
args: ['0x...']
})
address (string): Contract addressabi (Abi): Contract ABIfunctionName (string): Function name to callargs (ContractValue[], optional): Function argumentsprovider (PublicClient, optional): Override provider
Returns: Promise<unknown>
getBlock
Returns block information for a given block tag.
const block = await adapter.getBlock('latest')
blockTag (BlockTag): Block tag (e.g., ‘latest’, ‘pending’, block number)provider (PublicClient, optional): Override provider
Returns: Promise<Block>
getContract
Creates a contract instance with a compatible interface.
const contract = adapter.getContract('0x...', contractAbi)
const result = await contract.read.functionName()
address (string): Contract addressabi (Abi): Contract ABI
Returns: GenericContract
setSigner
Sets or updates the signer for the adapter.
const newAccount = privateKeyToAccount('0x...')
adapter.setSigner(newAccount)
signer (Account | PrivateKey): New signer to use
setProvider
Sets or updates the provider for the adapter.
const newProvider = createPublicClient({ chain: mainnet, transport: http() })
adapter.setProvider(newProvider)
provider (PublicClient): New provider to use
Returns: PublicClient
signerOrNull
Returns the signer adapter or null if not set.
const signer = adapter.signerOrNull()
if (signer) {
// Use signer
}
ViemSignerAdapter | null
createSigner
Creates a new signer adapter from an account or private key.
const signerAdapter = adapter.createSigner(account)
signer (Account | PrivateKey | ViemSignerAdapter): Signer to wrap
Returns: ViemSignerAdapter
Usage Examples
With Wagmi
import { useWalletClient, usePublicClient } from 'wagmi'
import { ViemAdapter } from '@cowprotocol/sdk-viem-adapter'
function MyComponent() {
const publicClient = usePublicClient()
const { data: walletClient } = useWalletClient()
const adapter = new ViemAdapter({
provider: publicClient,
walletClient: walletClient
})
// Use adapter with SDK
}
With Private Key
import { ViemAdapter } from '@cowprotocol/sdk-viem-adapter'
import { http, createPublicClient, privateKeyToAccount } from 'viem'
import { mainnet } from 'viem/chains'
const account = privateKeyToAccount('0x...')
const provider = createPublicClient({
chain: mainnet,
transport: http('https://eth.llamarpc.com')
})
const adapter = new ViemAdapter({ provider, signer: account })
With CoW SDK
import { CowSdk, SupportedChainId } from '@cowprotocol/cow-sdk'
import { ViemAdapter } from '@cowprotocol/sdk-viem-adapter'
import { http, createPublicClient, privateKeyToAccount } from 'viem'
import { sepolia } from 'viem/chains'
const account = privateKeyToAccount('YOUR_PRIVATE_KEY' as `0x${string}`)
const transport = http('YOUR_RPC_URL')
const provider = createPublicClient({ chain: sepolia, transport })
const adapter = new ViemAdapter({ provider, signer: account })
const sdk = new CowSdk({
chainId: SupportedChainId.SEPOLIA,
adapter,
tradingOptions: {
traderParams: {
appCode: 'YOUR_APP_CODE',
},
options: {
chainId: SupportedChainId.SEPOLIA,
},
},
})
const orderId = await sdk.trading.postSwapOrder(parameters)
See Also
