Developer Quickstart

Deploy a smart contract that can request and receive random numbers

In order to receive randomness for your smart contract, simply grab the oracle interface and address from the snippet below and get going!
Steps
1.Copy the following code and replace line 55 (# Do something with RNG) with your code that makes use of the random number.
2.​Compile, declare, deploy the contract on StarkNet.
Sample Code
%lang starknet
​
%builtins pedersen range_check
​
from starkware.cairo.common.uint256 import Uint256
from starkware.starknet.common.syscalls import get_caller_address, get_block_timestamp
from starkware.cairo.common.cairo_builtins import HashBuiltin
from starkware.cairo.common.cairo_secp.bigint import BigInt3
​
@contract_interface
namespace IRNGOracle {
    func request_rng(beacon_address: felt) -> (requestId: felt) {
    }
}
​
@storage_var
func oracle_address() -> (addr: felt) {
}
​
@storage_var
func beacon_address() -> (address: felt) {
}
​
@constructor
func constructor{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr}(
    oracle_addr: felt, _beacon_address: felt
) {
    oracle_address.write(oracle_addr);
    beacon_address.write(_beacon_address);
​
    return ();
}
​
@external
func request_rng{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr}() -> (
    request_id: felt
) {
    let (oracle) = oracle_address.read();
    let (_beacon_address) = beacon_address.read();
    let (request_id) = IRNGOracle.request_rng(
        contract_address=oracle, beacon_address=_beacon_address
    );
    return (request_id,);
}
​
@external
func will_recieve_rng{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr}(
    rng: BigInt3, request_id: felt
) {
    let (oracle) = oracle_address.read();
    let (caller_address) = get_caller_address();
​
    assert oracle = caller_address;
​
    // # Do something with RNG
​
    return ();
}
​

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Last modified 5mo ago