contract-ts

Guest Book Contract

The smart contract stores messages from users. Messages can be premium if the user attaches sufficient money (0.1 $NEAR).

this.messages = [];

@call
// Public - Adds a new message.
add_message({ text }: { text: string }) {
  // If the user attaches more than 0.1N the message is premium
  const premium = near.attachedDeposit() >= BigInt(POINT_ONE);
  const sender = near.predecessorAccountId();

  const message = new PostedMessage({premium, sender, text});
  this.messages.push(message);
}
  
@view
// Returns an array of messages.
get_messages({ fromIndex = 0, limit = 10 }: { fromIndex: number, limit: number }): PostedMessage[] {
  return this.messages.slice(fromIndex, fromIndex + limit);
}

Quickstart

1. Make sure you have installed node.js >= 16.
2. Install the NEAR CLI

1. Build and Test the Contract

You can automatically compile and test the contract by running:

npm run test

2. Create an Account and Deploy

You can create a testnet account and deploy the contract by running:

near create-account <your-account.testnet> --useFaucet
near deploy <your-account.testnet> build/release/hello_near.wasm

3. Retrieve the Stored Messages

get_messages is a read-only method (view method) that returns a slice of the vector messages.

View methods can be called for free by anyone, even people without a NEAR account!

near view <your-account.testnet> get_messages '{"from_index":0, "limit":10}'

4. Add a Message

add_message adds a message to the vector of messages and marks it as premium if the user attached more than 0.1 NEAR.

add_message is a payable method for which can only be invoked using a NEAR account. The account needs to attach money and pay GAS for the transaction.

# Use near-cli to donate 1 NEAR
near call <your-account.testnet> add_message '{"text": "a message"}' --amount 0.1 --accountId <your-account.testnet>

Tip: If you would like to add a message another account, first login into NEAR using:

# Use near-cli to login your NEAR account
near login

and then use the logged account to sign the transaction: --accountId <your-account.testnet>.