MetaMask displaying wrong value when making RPC sendTransaction call

Question

I have been trying to send a transaction using an RPC call with MetaMask's window.ethereum.request injected method.

I have successfully sent a transaction before, by using the web3js method web3.eth.sendTransaction with MetaMask displaying the intended amount of ether. For the conversion from ether to wei I'm using web3.utils.toWei("3", "ether).

However, when I try to send a transaction using an RPC call, the MetaMask pop-up displays an incorrect amount of ether to be sent. The accounts used below are provided by Ganache. The sender address belongs to the account I have successfully connected to my app using MetaMask.

I am using Ganache as a local network and Firefox on Ubuntu. This is the code used to make the call:

 const myParameters = {
    from: "0x5c0bC92f7d26F7AD821408e2B1774FC96858C691",
    to: "0x6cC5550509CC3a66Df97Efa42B866A058e12ADE2",
    value: web3.utils.toWei("3", "ether")
    };

let results = await window.ethereum.request({method:"eth_sendTransaction", params: [myParameters]});

I have also tried converting the value to string, but I get the same wrong amount. Here's the pop-up I get for the above code:

Answer 1

Value should be in hex format.

Note: in some updated MetaMask installation, it seems the injected web3 has not the utils package anymore, so you may need to use web3.toWei instead.

 const myParameters = {
    from: "0x5c0bC92f7d26F7AD821408e2B1774FC96858C691",
    to: "0x6cC5550509CC3a66Df97Efa42B866A058e12ADE2",
    value: parseInt(web3.utils.toWei("3","ether")).toString(16)
    };

let results = await window.ethereum.request({method:"eth_sendTransaction", params: [myParameters]});

Answer 2

The accepted answer is actually not the best way to handle it. You don't need to go back and forth converting from integer and then to string to get the value. Web3 has everything you need to get the right amount:

const wei = web3.utils.toWei('3', 'ether')
await window.ethereum
    .request({
        method: 'eth_sendTransaction',
        params: [
            {
                from: '0x5c0bC92f7d26F7AD821408e2B1774FC96858C691',
                to: '0x6cC5550509CC3a66Df97Efa42B866A058e12ADE2',
                value: web3.utils.toHex(wei),
            },
        ],
    })