Forem: Subroto Kumar

How To Deploy A Smart Contract On Blockchain Using Python

Subroto Kumar — Mon, 23 May 2022 16:41:09 +0000

Dependencies

Python

web3.py :
Web3.py is a Python library for interacting with Ethereum.

It’s commonly found in decentralized apps (dapp) to help with sending transactions, interacting with smart contracts, reading block data, and a variety of other use cases.

Installation:
pip install web3

Py-solc-x | Py-solc :

Py-solc is a Python wrapper and version management tool for the solc Solidity compiler

Installation:
pip install py-solc-x

Ganache UI | Cli

Installation:

Ganache Desktop Download Link OR

Ganache-cli : pip install ganache-cli

Lets Get Started

1. Open the directory where you have put your smart contract in the code editor like VSCode.

2. Create solidity file SmartContractDemo.sol.

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

contract SmartContractDemo {
    struct Person {
        string name;
        string dateOfBirth;
    }

    Person[] public idCard;

    function numberOfEntries() public view returns (uint256) {
        return idCard.length;
    }

    function store(string memory _name, string memory _birthday) public {
        idCard.push(Person(_name, _birthday));
    }

    function changeData(
        uint256 index,
        string memory _name,
        string memory _birthday
    ) public {
        require(index <= numberOfEntries(), "Given index not present");
        idCard[index] = Person(_name, _birthday);
    }

    function retrieve(uint256 index)
        public
        view
        returns (string memory, string memory)
    {
        require(index <= numberOfEntries(), "Given index not present");
        return (idCard[index].name, idCard[index].dateOfBirth);
    }
}

3. Next create a python file deploy.py. Here, we write the code required to push our contract to the blockchain.

4. First add the below code to import the web3 and py-solc-x in python files:

from web3 import Web3
from solcx import compile_standard, install_solc

import json

5. Read and store the content of SmartContractDemo.sol in a separate variable:

# extract the content of SmartContractDemo.sol
with open("./SmartContractDemo.sol", "r") as file:
    smart_contract_demo = file.read()

6. Run the below code to install solc and compile the solidity code:

install_solc("0.6.0")

# Solidity source code
compiled_sol = compile_standard(
    {
        "language": "Solidity",
        "sources": {"SmartContractDemo.sol" : { "content" : smart_contract_demo_file }},
        "settings": {
            "outputSelection": {
                "*": {
                    "*": ["abi","metadata","evm.bytecode","evm.sourceMap"]
                }
            }
        }
    },
    solc_version="0.6.0",
)

7. The below code will put in the compiled_code as a new JSON file.

with open("compiled_code.json","w") as file:
    json.dump(compiled_sol,file)

8. Now before we deploy this contract, we need abi and bytecode first which we can get from compiled_code. This can be achieved by using this code:

# get abi
abi = compiled_sol["contracts"]["SmartContractDemo.sol"]["SmartContractDemo"]["abi"]

# bytecode
bytecode = compiled_sol["contracts"]["SmartContractDemo.sol"]["SmartContractDemo"]["evm"]["bytecode"]["object]

9. Connecting to Ganache:

To connect with ganache, we need an HTTP Provider URL, chain-id, the public key & private key which will be going to be used for deploying our smart contract.

How to get HTTP provider, chain-id, the public and private key of Transaction account:

If you are using Ganache UI

Step 1: Open Ganache App.

Step 2: Click on the Quickstart button.

This is what Ganache-UI looks like were

White-outlined box give us the RPC server i.e., http://127.0.0.1:7545
Yellow-outlined box give us chain_id i.e, 5777
Red-outlined box marks the public key of the account e.g., 0xE1584b4d8f1b0CeEF97190B296DaF446674A3d63
Blue-outlined box point to the button will show the private key associated with the given account

If you are using Ganache-CLI

Step 1: Open a terminal and then run the given command: ganache-cli.

This will launch the ganache-cli terminal.

Step 2: Copy and note the public key and private key associated with any account, clain-id, and RPC server url which is http://127.0.0.1:8545 in my case.

Important Note:

Accounts provided in the Ganache are only meant for development and testing purposes. Please, don't try to do actual transactions.
Private keys are highly confidential. So, keep your private keys safe. It allows the user to access the wallet.

10. Managing private key

Adding private key:

Even if we are just using the private key associated with ganache, for best practice we should always avoid hard coding private key in our coding.

So, to store the private key, we will add it as an environment variable and extract it in our python program deploy.py using OS module.

To do so :

Inside same directory, add a file .env
Open .env file and write: export $PRIVATE_KEY=<put your private key here> e.g., ![[Pasted image 20220523145104.png]]
Head back to deploy.py and import these module at the top: ![[Pasted image 20220523145413.png]]

11. Go back to our deploy.py and connect it with ganache.

# Connecting to ganache
w3 = Web3(Web3.HTTPProvider("http://127.0.0.1:8545"))
chain_id = 5777
my_address= "0xE1584b4d8f1b0CeEF97190B296DaF446674A3d63"
private_key = os.getenv("PRIVATE_KEY")

12. Now let's create the contract in python and get the latest transaction.

# Creating contract in python
SmartContractDemo = w3.eth.contract(abi=abi, bytecode=bytecode)

# Get the latest transaction
transaction = SmartContractDemo.constructor().buildTransaction({
    "chainId": chain_id,
    "gasPrice": w3.eth.gas_price,
    "from": my_address,
    "nonce": nonce,
})

13. Finally, let's sign our transaction and deploy it.

# Sign the transaction
signed_txn = w3.eth.account.sign_transaction(transaction, private_key=private_key)

print("Deploying Contract!")
# Sent it
tx_hash = w3.eth.send_raw_transaction(signed_txn.rawTransaction)

# Wait for the transaction to be mined, and get the transaction receipt
print("Waiting for Transaction to finish...")

tx_receipt=w3.eth.wait_for_transaction_receipt(tx_hash)
print(f"Done! Contract Deployed to {tx_receipt.contractAddress}")

Well done! We have successfully learned to deploy Smart Contract to the local blockchain.

Interacting with our smart contract

There are two types of Interaction one can make with a Smart Contract:

Call -> Simulate making the call and getting a return value
Transact -> Actually make a state change

Let's perform both the interaction with our smart contract :

1. To call a public function numberOfEnteries()from SmartContractDemo, go back to deploy.py.

# Working with the contracts
smart_contract_demo = w3.eth.contract(address=tx_receipt.contractAddress, abi=abi)

print(f"Number of Enteries in idCard array is {smart_contract_demo.functions.numberOfEnteries()}")

2. Now a state change by adding a data to the idCard array using the function store():

store_transaction = smart_contract_demo.functions.store("Naruto", "10-10-1999").buildTransaction({
    "chainId": chain_id,
    "gasPrice": w3.eth.gas_price,
    "from":my_address,
    "nonce":nonce+1,
})

signed_store_txn = w3.eth.account.sign_transaction(
    store_transaction, private_key=private_key
)

signed_store_hash = w3.eth.send_raw_transaction(signed_store_txn.rawTransaction)

tx_receipt = w3.eth.wait_for_transaction_receipt(signed_store_hash)

Whenever we make a state change, the transaction has to be signed first with our private key.

Note:
Calling a view or pure public function doesn't cost anything.
Whereas deploying a smart contract and making a function call that changes the state of the blockchain cost some amount of GAS Fees.

3. Finally, finish it by again calling numberOfEnteries() function and retrieve() function.

print(f"Number of Enteries in idCard array is {smart_contract_demo.functions.numberOfEnteries()}")

print(f"Person at 0th index in idCard array is {smart_contract_demo.functions.idCard(0)}")

4. Now run the deploy.py file (run via terminal: python ./deploy.py).

OUTPUT:

Now, if we check the ganache-cli, we can find two transaction records there,

The First transaction is about contract creation.
The Second transaction is made we call the store function to add Personal detail to idCard array.

Resource Link

Project Link:

GitHub: https://github.com/subrotokumar/SmartContractDemo

Documentation:

web3.py : https://web3py.readthedocs.io/en/stable/
py-solc-x : https://solcx.readthedocs.io/en/latest/

CONNECT WITH ME

I hope you have found this article helpful. Thank you for reading!

How to setup WSL2 and run Linux GUI apps in Windows operating system

Subroto Kumar — Fri, 01 Apr 2022 18:25:24 +0000

Windows Subsystem for Linux (WSL) is a Windows tool that allows developers run a GNU/Linux environment, install packages from the Ubuntu and other Linux archive, and run Linux applications and workflows directly on Windows, unmodified, without the overhead of a traditional virtual machine or dual-boot setup.

Installing WSL2

There are two ways by which we can install wsl2 in windows operating system and this depends on your windows version and build number.
To check your windows version:

Press WIN + R , type winver and then press ENTER .

First Method (Easy Method)

Prerequisites : You must be running Windows 10 version 2004 and higher (Build 19041 and higher) or Windows 11.

1. First we have to open a command prompt with administrator privileges.

Select Start, type PowerShell, right-click Windows PowerShell, and then select Run as administrator.

2. Run this command : wsl --install

This command will enable the required components, download the latest Linux kernal, set WSL 2 as default and install a Ubuntu (by default) distribution.
Only thing your have to do now is to set new Username and Password for your newly installed Ubuntu.

This above command will only works if you are installing WSL for first time and WSL is not installed at your PC at all.

If this method don't work for you then follow the next step.

3. Check the list of available Linux distributins available to download from the online store. To do so, run this command :
wsl --list --online or wsl -l -o .

4. Run this command to install your desired Linux Distribution: wsl --install -d <Distribution name>

Here : <Distribution name> should be same as one that one mention in NAME section.

For example, suppose I want to install Debian then i have to run this command : wsl --install -d Debian

5. Once the WSL install is completed your will need to set user account and password for your newly install Linux distribution.

Once everything is all done, close the terminal.
To open the installed Linux Distribution:
Select Start, type , and then Select and Run.

Second Method (Manual Method)

This method is more those computer which are running an older build of windows.

Step 1: Open PowerShell as Administrator (Start menu > PowerShell > right-click > Run as Administrator) and run this command :

dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart

This will enable the Windows System for Linux feature.

Step 2 : Enable Virtual Machine feature by running this command :

dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart

Step 3 : Restart the system and then run this command in PowerShell as Administrator.

wsl --set-deafult-version 2

Step 4 : Installing a Linux Distribution for your choice.

Open the Microsoft Store and select your favorite Linux Distribution. Here are following links for distribution available in Microsoft Store.

Step 5 : Once the Linux distribution of your choice is downloaded from Microsoft office. Open a newly installed Linux distribution, this will take you to Terminal window where rest of the installation will finish. This process will take a few minutes.

You will then need to create a user account and password for your new Linux distribution.

With this, You have successfully set up WSL2 in your windows machine.

Extra

To check list of all Linux Distribution and check which version for WSL it is running.
Use this command in PowerShell : wsl -l -v
To update from WSL 1 to WSL 2 on previously installed Linux distributions
Use this command : wsl --set-version <distro name> 2
To set the default Linux Distribution
Use this command : wsl -s <DistributionName> or wsl --setdefault <DistributionName>

Run Linux GUI Apps

Prerequisites :

Windows 11 Build 22000 or higher
Installed driver for vGPU
Linux GUI apps are only supported with WSL 2

If you just set-up WSL by using above methods, you're already ready to begin using Linux GUI apps on WSL!

For Existing WSL install

1. Open a command prompt/PowerShell as administrator.
2. Update the WSL
wsl --update
3. Shutdown the WSL by running this command
wsl --shutdown

Update the packages in your distribution

Run this command :

sudo apt update

Installing and running GUI-Apps in your distribution

Command for installing a package : sudo apt install <package-name>
Command to launch the package : <package name>

Now, lets install and launch Firefox. To do so, use this command sudo apt install firefox
sudo apt install firefox
This may some time depending upon your Internet Speed.
firefox

Thank you being with me and reading my article. If you like my post, follow me on Dev.to and do connect with me on LinkedIn and GitHub

What is Markdown and how you can use it to write README.md file for your GitHub project?

Subroto Kumar — Sun, 13 Mar 2022 18:04:18 +0000

Markdown is a lightweight markup language that allows us to write in easy-to-read text format and convert it into XHTML (or HTML) to display in a browser or another writing program.

Paragraph

Lorem ipsum dolor sit amet, consectetur adipiscing elit,
sed do eiusmod tempor incididunt ut
labore et dolore magna aliqua.

Output:

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

Line-Break

To insert a line break into your Markdown file, finish your line with at least two spaces and press ENTER key. It will render a new line for your text.

Hey there  
I'm a coder.

Output:

Hey there
I'm a coder.

Text Formatting

1. Using Italics in text

To use Italics in text, surround the targeted part of text with single asterisks (*) or single underscores (_).

This is *Morax*.
I'm a _programmer_.

Output:

This is Morax.
I'm a programmer.

2. Using Bold in text

Bold text is created by using two asterisks (**) or two underscores (__).

This is **Morax**.
I'm a __programmer__.

Output:

This is Morax.
I'm a programmer.

3. Using Asterisk or Underscore in a Text

To use a literal asterisk or Underscore in a text, precede it with an escape character backslash ()
e.g.,
\_This is all \*\*plain\*\* text\_.

Output:

_This is all **plain** text_.

Horizontal Line

To draw Horizontal rule, put three or more hyphens (-), asterisks (*), or underscores (_) in a new line.

_ _ _
* * *
_ _ _

Output:

Heading

# Heading 1
## Heading 2
### Heading 3
#### Heading 4
##### Heading 5
###### Heading 6

Output:

Heading 1

Heading 2

Heading 3

Heading 4

Heading 5

Heading 6

Making List

Ordered List

1. Java
2. Python
3. Go

Output:

Java
Python
Go

Unordered List

- Java
  - Core Java
  - Advance Java
- Python
- Go

Output:

Java
- Core Java
- Advance Java
Python
Go

Tracking task lists

- [x] Windows
- [x] Linux
- [ ] MacOS

Output:

Building Table

Language | Use 1 | Use 2
- | - | -
Java | Mobile App Development | Cloud-based Application
Python | AL & ML | Data analytics
C# | Game Development | Mobile Apps

Output:

Language	Use 1	Use 2
Java	Mobile App Development	Cloud-based Application
Python	AL & ML	Data analytics
C#	Game Development	Mobile Apps

Quoting Text

> "If you don't take risks, you can't create a future!" - Monkey D. Luffy`

Output:

"If you don't take risks, you can't create a future!" - Monkey D. Luffy

> I’ll leave tomorrow’s problems to tomorrow’s me.” – Saitama
> “Being weak is nothing to be ashamed of… Staying weak is !!“ – Fuegoleon Vermillion

Output:

I’ll leave tomorrow’s problems to tomorrow’s me.” – Saitama
“Being weak is nothing to be ashamed of… Staying weak is !!“ – Fuegoleon Vermillion

Link and Image

Using Image

Syntax:

![Image_discription](image-url)

![Picture](https://images.unsplash.com/photo-1496065187959-7f07b8353c55?ixlib=rb-1.2.1&ixid=MnwxMjA3fDB8MHxzZWFyY2h8MTJ8fHRlY2hub2xvZ3l8ZW58MHx8MHx8&auto=format&fit=crop&w=500&q=60)

Output:

Using Link

Syntax:

[Link-text](url)

[My Linkedin](https://www.linkedin.com/in/kumarsubroto)

Output:

My Linkedin

Code snippets

This is `code`

Output:

This is code

Code Blocks

Syntax:

Output:

Syntax:

Output:

Extra-Resources

Github Markdown Emoji

Thank you being with me and reading my article. If you like my post, follow me on Dev.to and do connect with me on LinkedIn and GitHub.