Technical Perspectives | Contract Upgrade for Python Smart Contract Tutorial

01 lead

In the previous technical point of view, we introduced the contract native API and described how to use smart contracts for ONT / ONG transfers. In this issue we will discuss how to upgrade a contract through the Upgrade API . There are 2 APIs for contract upgrades, Destroy and Migrate . Its usage is as follows:

Let's take a closer look at how to use these two APIs. Prior to this, the small partners can create a new contract in the Ontology Smart Contract Development Tool SmartX and follow us. As with the previous API tutorial, we will give a video example of this tutorial at the end of the article.

02 Upgrade API How to use

  From ontology.interop.Ontology.Contract import Migrate 

From ontology.interop.System.Contract import Destroy

  From ontology.interop.System.Contract import Destroy 

From ontology.interop.System.Runtime import Notify

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Def Main(operation, args):

If operation == "destroy_contract":

Return destroy_contract()

Return False

Def destroy_contract():

Destroy() # call destroy to destroy this contract

Notify(["The contract has been destoryed"])

Return True You can see the results of this sample code on SmartX:

1. Paste the above code into SmartX to compile and deploy;
2. Clicking on the deployment again will pop up "Contract deployment failed, the contract has been deployed" because the same contract already exists on the chain;

3. Run the destroy_contract function to destroy the contract;

4. Click on the deployment contract again and you will find that the contract can be deployed again. It will not pop up again. "Contract deployment failed, the contract has been deployed." This can prove that the original contract has been destroyed in the chain.

•   From ontology.interop.Ontology.Contract import Migrate
   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) # Call Migrate to migrate this contract if res:
Notify(["Migrate successfully"])
New_contract_hash=AddressFromVmCode(avm_code) # Calculate the new contract address Notify(new_contract_hash) # Print out the new contract address return True
Else:
Return False

1. Paste the above code into SmartX compilation and fill in the parameters. Pay special attention to the following two points when filling in parameters: a. To confirm that avm_code does not exist on the chain, it will report an error; b. Migrate requires a higher gas limit, so adjust the gas limit when running the function.

If you want to try to develop on the ontology public chain, please add the ontology research assistant: ontresearch, join the ontology technology community to discuss!

We will continue to update Blocking; if you have any questions or suggestions, please contact us!