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How to Upgrade a Smart Contract

Version 0.1

1. Introduction

API Return Value Description
Destroy none Destroy a smart contract
Migrate contract structure Upgrade a smart contract. The existing contract will be replaced by the newly migrated contract

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

2. Destroy

The existing contract will be deleted from the persistent storage area.

Example

from ontology.interop.Ontology.Contract import Migrate
from ontology.interop.System.Contract import Destroy
from ontology.interop.System.Runtime import Notify

def Main(operation, args):
    if operation == "destroy_contract":
        return destroy_contract()

    return False


def destroy_contract():
    Destroy()
    Notify(["The contract has been destoryed"])
    return True

3. Migrate

The existing contract will be replaced by the newly migrated contract. The data saved by the old contract will also be migrated to the new contract. The old contract will be deleted after migration.

Migrate parameters

Param Description
script avm code
need_storage Need persistent storage or not
name Author name
version Contract version
author Contract author
email Developer email
description Contract description

Example

from ontology.interop.Ontology.Contract import Migrate
from ontology.interop.System.Contract import Destroy
from ontology.interop.System.Runtime import Notify
from ontology.libont import AddressFromVmCode

def Main(operation, args):
    if operation == "migrate_contract":
        if len(args) != 7:
            return False
        avm_code = args[0]
        need_storage = args[1]
        name = args[2]
        version = args[3]
        author = args[4]
        email = args[5]
        description = args[6]
        return migrate_contract(avm_code, need_storage, name, version, author, email, description)

    return False


def migrate_contract(avm_code, need_storage, name, version, author, email, description):
    res = Migrate(avm_code, need_storage, name, version, author, email, description)
    if res:
        Notify(["Migrate successfully"])
        new_contract_hash=AddressFromVmCode(avm_code)
        Notify(new_contract_hash)
        return True
    else:
        return False

Follow up question: How to improve this contract?

Answer: Add CheckWitness().

4. Contributing

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