requireRecipient Function

The function is declared in action.ts in asm-chain as follows:

function requireRecipient(name: Name): void

The requireRecipient function is used to notify other contracts that this contract has called a certain action, which is the action where requireRecipient is called. If the notified contract has the same action, then this action will be called.

The following sender and receiver code demonstrates how to send a notification from one contract to another.

// sender
import {
    print,
    requireAuth,
    requireRecipient,

    Name,
    Contract,
} from "asm-chain";

@contract
class MyContract extends Contract {
    @action("sayhello")
    sayHello(name: Name): void {
        print(`hello ${name}!`);
        requireAuth(name);
        requireRecipient(Name.fromString('hello'));
    }
}

//receiver.ts
import {
    Name,
    Contract,

    print,
} from "asm-chain";

@contract
class MyContract extends Contract {
    @action("sayhello", notify)
    sayHello(name: Name): void {
        print(`notify: hello ${name}!`);
    }
}

Let's explain the code:

• The sender contract code is deployed in the alice contract account. The sayhello action in it calls the requireRecipient function to notify the hello account that it has called the sayhello action.
• The receiver contract code is deployed in the hello account. From the following code, the line #[chain(action="test", notify)] is different from the normal action code. The notify parameter indicates that this action is used to receive notifications from other contracts. For an action that receives notifications, its self.receiver and self.first_receiver are not the same. In this case, self.first_receiver is the alice account and self.receiver is hello. You can view the output of chain_println!(self.receiver, self.first_receiver); during the test run to know this.

@action("sayhello", notify)
sayHello(name: Name): void {
    print(`notify: hello ${name}!`);
}

Below is the test code:

@chain_test
def test_notify(tester):
    deploy_contracts(tester)
    args = {'name': 'alice'}
    r = tester.push_action('alice', 'sayhello', args, {'alice': 'active'})
    logger.info('++++++elapsed: %s', r['elapsed'])
    tester.produce_block()

Compilation:

cd examples/notify
yarn
yarn build

Testing:

ipyeos -m pytest -s -x test.py -k test_notify

Output:

[(alice,sayhello)->alice]: CONSOLE OUTPUT BEGIN =====================
hello alice!
[(alice,sayhello)->alice]: CONSOLE OUTPUT END   =====================
[(alice,sayhello)->hello]: CONSOLE OUTPUT BEGIN =====================
notify: hello alice!
[(alice,sayhello)->hello]: CONSOLE OUTPUT END   =====================

Example code

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