chore: example for msg send with eip-712 (evmos#83)

Author: miliPaoletti

examples/messages/basic/msgSendWithEip712.md

@@ -0,0 +1,82 @@
+# Message Send with Eip712
+
+Send coins to another wallet and check wallet balance
+
+```ts
+import { ethToEvmos } from '@evmos/address-converter'
+import { Wallet } from '@ethersproject/wallet'
+import { getSender, MAINNET_CHAIN, MAINNET_FEE, broadcast,  singTransactionUsingEIP712 } from '@hanchon/evmos-ts-wallet'
+import { createMessageSend, MessageSendParams, Sender} from '@evmos/transactions'
+
+// CONSTANTS
+const privateKey = "pluck view carry maid bamboo river major where dutch wood certain oval order wise awkward clerk adult summer because number raven coil crunch hat"
+const url = 'https://rest.bd.evmos.org:1317'
+const urlBalance = 'https://rest.bd.evmos.org:1317/cosmos/bank/v1beta1/balances/'
+
+
+async function fetchGet(route: string){
+    try {
+        const request = await fetch(route)
+        if (request.status !== 200){
+            return "0"
+        }
+        const response = await request.json()
+        return response
+    } catch (e) {
+        console.log(e);
+        console.error("Error calling fetch GET: " + e);
+        return "0";
+    }
+}
+
+async function getWalletBalance (wallet: string, urlBalance: string): Promise<string> {
+    // given a wallet, it returns the balances and pagination
+    const requestUrl = urlBalance + wallet
+    let response = await fetchGet(requestUrl)
+    // if there was an error
+    if (response === "0"){
+        return "0"
+    }
+
+    const balances = response.balances
+
+    if (balances.length !== 0){
+        return balances[0].amount
+    }else {
+        return "0"
+    }
+}
+
+async function signAndBroadcastTx(wallet: Wallet, sender: Sender, url: string) {
+    const params: MessageSendParams = {
+        destinationAddress: 'evmos1pmk2r32ssqwps42y3c9d4clqlca403yd9wymgr',
+        amount: '1',
+        denom: 'aevmos',
+    }
+    let fee = MAINNET_FEE
+    // the fee amount it has to be bigger than the gas
+    fee.gas = "150000"
+    fee.amount = '3000000000000000'
+
+    // create the message
+    const message = createMessageSend(MAINNET_CHAIN, sender, MAINNET_FEE, 'message', params)
+    // sign the tx
+    let txBody = await singTransactionUsingEIP712(wallet, sender.accountAddress, message, MAINNET_CHAIN)
+    // broadcast the tx signed
+    await broadcast(txBody, url)
+}
+
+async function main(){
+    // create a wallet using the private keys
+    const wallet = Wallet.fromMnemonic(privateKey)
+    // For sending txns it's needed: accountNumber, sequence, pubkey
+    const sender = await getSender(wallet, url)
+    /*  getSender: returns the accountAddress, the sequence,
+        the accountNumber and the pubkey
+        If the pubkey is not created, it has a method that 'creates' it
+    */
+    await signAndBroadcastTx(wallet, sender, url)
+    await getWalletBalance(sender.accountAddress, urlBalance)
+}
+
+main()