Metamask display for signing data with eth_signTypedData_v4

Question

I am using the latest implementation of EIP712 to ask for user to confirm some action:

        web3.currentProvider.sendAsync({
            method: "eth_signTypedData_v4",
            params: [account, dataToSign],
            from: account
        }

with:

        const metaTransactionType = [
            { name: "permission", type: "string" }
        ];
        ...
        let message = {
            permission: "Hello world"
        };
        ...
        const dataToSign = JSON.stringify({
            types: {
                EIP712Domain: domainType,
                MetaTransaction: metaTransactionType
            },
            domain: domainData,
            primaryType: "MetaTransaction",
            message: message
        });

And everything works fine, but the Metamask pop up shows the word "Message" twice:

Metamask version is 8.1.5 (the latest I believe). Is this a bug or am I constructing the data to sign wrong?

Thanks!

Answer 1

This is the normal behavior. I also had the word "Message" showing up twice when working with EIP-712 a few months ago.

I tried at the time to modify the variable "message" in the js code but it was useless. I believe there is currently no way to change this.

It would indeed be an interesting feature to customize this Metamask window.