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course06_use_runtime_api_in_smart_contract.md

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How to Use Runtime API in Smart Contract

Version 0.1

1. Introduction

API Return Value Description
Runtime.GetTime uint Return timestamp of the most recent block
GetCurrentBlockHash string Return block hash of the most recent block
Runtime.Notify(object[]) void In smart contract, sending notifications (including socket notifications or rpc queries) to clients that are executing this smart contract
Serialize(item) byte array Serializes an item into a bytearray
Deserialize(item) original type Deserializes an item from a bytearray
Base58ToAddress(base58_address) byte array Convert a base58 address to address in form of byte array
AddressToBase58(address) string Convert an address in form of byte array to a base58 address
Runtime.CheckWitness(hash_or_pubkey : byte[]) bool Verify operational permissions of user or contract

For more details, you can view the API-doc and the source code here.

2. How to use Runtime API

Import package

from ontology.interop.System.Runtime import GetTime, CheckWitness, Log, Notify, Serialize, Deserialize
from ontology.interop.Ontology.Runtime import Base58ToAddress, AddressToBase58, GetCurrentBlockHash

Notify: In smart contract, sending notifications (including socket notifications or rpc queries) to clients that are executing this smart contract

from ontology.interop.System.Runtime import GetTime, CheckWitness, Log, Notify, Serialize, Deserialize

def Main(operation):
    if operation == 'demo':
        return demo()
    return False


def demo():
    Notify("hello world")

GetTime: Return timestamp of the most recent block

from ontology.interop.System.Runtime import GetTime

def Main(operation):
    if operation == 'demo':
        return demo()
    return False


def demo():
    time=GetTime()
    return time # return a uint num

GetCurrentBlockHash: Return block hash of the most recent block

from ontology.interop.Ontology.Runtime import GetCurrentBlockHash

def Main(operation):
    if operation == 'demo':
        return demo()
    return False
    
def demo():
    block_hash = GetCurrentBlockHash()
    return block_hash

Serialize: Serialize the data from original type to byte array

Deserialize: Deserialize the data from byte array to original type

from ontology.interop.System.Runtime import GetTime, CheckWitness, Log, Notify, Serialize, Deserialize
from ontology.interop.System.Storage import Put, Get, GetContext

def Main(operation, args):
    if operation == 'serialize_to_bytearray':
        data = args[0]
        return serialize_to_bytearray(data)
    if operation == 'deserialize_from_bytearray':
        key = args[0]
        return deserialize_from_bytearray(key)
    return False


def serialize_to_bytearray(data):
    sc = GetContext()
    key = "1"
    byte_data = Serialize(data)
    Put(sc, key, byte_data)


def deserialize_from_bytearray(key):
    sc = GetContext()
    byte_data = Get(sc, key)
    data = Deserialize(byte_data)
    return data

Base58ToAddress: transfer a base58 address to address in form of byte array

AddressToBase58: transfer an address in form of byte array to a base58 address

from ontology.interop.System.Runtime import Log
from ontology.interop.Ontology.Runtime import Base58ToAddress, AddressToBase58

def Main(operation):
    if operation == 'demo':
        return demo()
    return False


def demo():
    base58_addr="AV1GLfVzw28vtK3d1kVGxv5xuWU59P6Sgn"
    addr=Base58ToAddress(base58_addr)
    Log(addr)
    base58_addr=AddressToBase58(addr)
    Log(base58_addr)

CheckWitness: Verify operational permissions of user or contract

from ontology.interop.System.Runtime import CheckWitness, Notify
from ontology.interop.Ontology.Runtime import Base58ToAddress
from ontology.builtins import bytearray

def Main(operation):
    if operation == 'demo':
        return demo()
    return False


def demo():
    addr=Base58ToAddress("AW8hN1KhHE3fLDoPAwrhtjD1P7vfad3v8z")
    res=CheckWitness(addr)
    Notify(res)
    return res

3. Contributing

Please feel free to give any suggestion and help us make video better!
Contact: Yue Zhao 
Wechat: 16621171248
Email: messixaviinsta0303@163.com