How to use _signTypedData?

[khoanguyen-yang]

I used _signTypedData for this message (example taken from WalletConnect test application).

It threw an error Error: ambiguous primary types or unused types: "EIP712Domain", "RelayRequest"...

Which part of the message should I sign using _signTypedData?

{
  "types": {
    "EIP712Domain": [
      { "name": "name", "type": "string" },
      { "name": "version", "type": "string" },
      { "name": "verifyingContract", "type": "address" }
    ],
    "RelayRequest": [
      { "name": "target", "type": "address" },
      { "name": "encodedFunction", "type": "bytes" },
      { "name": "gasData", "type": "GasData" },
      { "name": "relayData", "type": "RelayData" }
    ],
    "GasData": [
      { "name": "gasLimit", "type": "uint256" },
      { "name": "gasPrice", "type": "uint256" },
      { "name": "pctRelayFee", "type": "uint256" },
      { "name": "baseRelayFee", "type": "uint256" }
    ],
    "RelayData": [
      { "name": "senderAddress", "type": "address" },
      { "name": "senderNonce", "type": "uint256" },
      { "name": "relayWorker", "type": "address" },
      { "name": "paymaster", "type": "address" }
    ]
  },
  "domain": {
    "name": "GSN Relayed Transaction",
    "version": "1",
    "chainId": 42,
    "verifyingContract": "0x6453D37248Ab2C16eBd1A8f782a2CBC65860E60B"
  },
  "primaryType": "RelayRequest",
  "message": {
    "target": "0x9cf40ef3d1622efe270fe6fe720585b4be4eeeff",
    "encodedFunction": "0xa9059cbb0000000000000000000000002e0d94754b348d208d64d52d78bcd443afa9fa520000000000000000000000000000000000000000000000000000000000000007",
    "gasData": {
      "gasLimit": "39507",
      "gasPrice": "1700000000",
      "pctRelayFee": "70",
      "baseRelayFee": "0"
    },
    "relayData": {
      "senderAddress": "0x22d491bde2303f2f43325b2108d26f1eaba1e32b",
      "senderNonce": "3",
      "relayWorker": "0x3baee457ad824c94bd3953183d725847d023a2cf",
      "paymaster": "0x957F270d45e9Ceca5c5af2b49f1b5dC1Abb0421c"
    }
  }
}

Many thanks.

[khoanguyen-yang]

It turns out I have to use signTypedData_v4 from eth-sig-util

[zemse]

You may look at this small post incase it's helps https://dev.to/zemse/ethersjs-signing-eip712-typed-structs-2ph8

[dellwatson]

but it's weird, if i look into the Wallet there's _signTypedData but I cannot use it either. I'mnot sure why

[koppishere]

@khoanguyen-yang you can use _signTypedData, just remove EIP712Domain from types

[georgiod9]

But this doesn't make sense. The whole point is to include the EIP712Domain in the type data. I am running across the same issue. When I remove EIP712Domain from the TypedData it works.

[koppishere]

I believe ethers adds it by default, so you do include it in the end.

[georgiod9]

I believe ethers adds it by default, so you do include it in the end.

Yes, i figured it out. The domain is set as a separate parameter in the typed object.

But my concern is that the types aren't declared explicitly. Seems like ethers has an implicit way to deduce the types

[nftchance]

For those that are only making it here now, yes, ethers does have a way to infer the primaryType. You can find the full discussion at: #3614 (comment)