<p style="margin-left:0px;">For Python developers looking to interact with Ethereum, web3.py is the go-to library. This guide shows you how to use web3.py with BuildBear RPC to test, deploy, and manage dApps effortlessly within a realistic testing environment. We’ll also demonstrate how Web3.py, with BuildBear's RPC, interacts with the PancakeSwap Lottery smart contract on the Binance Chain.</p><h2 style="margin-left:0px;">What you will learn:</h2><ol style="list-style-type:decimal;"><li>What is Web3.py</li><li>How to use Web3.py on BuildBear.</li><li>Interacting withPancakeSwap smart contracts using web3.py</li></ol><h2 style="margin-left:0px;">What is Web3.py?</h2><p style="margin-left:0px;">web3.py is a Python library that greatly simplifies the way you connect with Ethereum networks. It is similar to what ethers.js and web3.js do for JavaScript, enabling developers to transact with the blockchain.</p><p style="margin-left:0px;">Here is an illustration, library helps connect with Ethereum:</p><figure class="image image_resized" style="width:50%;"><img src="https://strapi.buildbear.io/uploads/1_946f515e1b.png" alt="1.png" srcset="https://strapi.buildbear.io/uploads/thumbnail_1_946f515e1b.png 245w,https://strapi.buildbear.io/uploads/small_1_946f515e1b.png 500w,https://strapi.buildbear.io/uploads/medium_1_946f515e1b.png 750w,https://strapi.buildbear.io/uploads/large_1_946f515e1b.png 1000w," sizes="100vw"></figure><p style="margin-left:0px;">&nbsp;</p><p style="margin-left:0px;"><i>Image credit: </i><a href="https://iotbl.blogspot.com/2017/03/ethereum-and-blockchain-2.html"><i>iotbl</i></a><i>.</i></p><p style="margin-left:0px;"><code>web3.py</code> lets us communicate with the blockchain using JSON-RPC, allowing you to interact with the entire blockchain through that single connection. It’s like using a single access point to read data or send transactions to the network. With <code>web3.py</code>, you can easily check balances, call functions in smart contracts, or submit new transactions by communicating with a single node that shares data with the whole blockchain network.</p><p style="margin-left:0px;">&nbsp;</p><p style="margin-left:0px;">Web3.py is well-suited for projects built using Python and has a user-friendly API that is easy to use. The library also supports synchronous and asynchronous programming, allowing developers to choose the most appropriate method for their projects.</p><p style="margin-left:0px;">One of the main advantages of Web3.py is its easy-to-use API. The library has a simple and intuitive interface that makes it easy for developers to interact with the Ethereum blockchain. JSON RPC Support make it easy to integrate Web3.py into existing projects, and it also makes it easy to test and debug your code.</p><h3 style="margin-left:0px;">How to use Web3.py on BuildBear?</h3><p style="margin-left:0px;">To connect to a node on the mainnet/tetsnet using JSON-RPC, you need access to that blockchain node endpoint. This is where BuildBear comes in:</p><p style="margin-left:0px;">It provides a reliable and realistic testing environment with instant access to mainnet states with RPC URLs.</p><p style="margin-left:0px;">Unlimited token availability (ERC20 and Native tokens)</p><p style="margin-left:0px;">An explorer to debug and transaction traces</p><p style="margin-left:0px;">It provides a wide range of support for dev tools through its plugin architecture.</p><p style="margin-left:0px;">This setup simplifies the development process, making it easier and faster for developers to build and test applications. Now let us see how we can use the Python library with the BuildBear RPC URL.</p><h2 style="margin-left:0px;">Prerequisites</h2><ul><li>Install <a href="https://www.python.org/downloads/">Python 3.x</a></li></ul><p style="margin-left:0px;">You can check the version of Python (Python 3.8+ recommended) installed in your system by running the below command on the terminal:</p><pre><code class="language-plaintext">$ python3 --version</code></pre><ul><li>Install web3.py via pip.</li><li>BuildBear Account</li></ul><p style="margin-left:0px;">To get started, create a Sandbox on <a href="https://home.buildbear.io/">BuildBear</a> on the blockchain network. For this tutorial fork the Binance chain. If you’re new to BuildBear, create an account, and set up a Sandbox following our quick start <a href="https://www.buildbear.io/resources/quick-guide">guide</a>.</p><h2 style="margin-left:0px;">Setting Up the Project</h2><p style="margin-left:0px;">This project demonstrates how to use <code>web3.py</code> to interact with the PancakeSwap Lottery contract on the Binance Smart Chain. We’ll first go through basic <code>web3.py</code> functions to get familiar with common operations and then connect to PancakeSwap.</p><pre><code class="language-plaintext">mkdir dapp &amp;&amp; cd dapp</code></pre><p style="margin-left:0px;">Create a virtual environment with Python and activate.</p><pre><code class="language-plaintext">python3.12 -m venv myenv source myenv/bin/activate</code></pre><p style="margin-left:0px;">Install <code>web3.py</code> in your environment:</p><pre><code class="language-plaintext">pip install web3</code></pre><h3 style="margin-left:0px;">Connecting to BuildBear RPC</h3><p style="margin-left:0px;">Open the project in VS Code editor. Create a file name demo.py. Add the following code to connect to BuildBear’s RPC and verify the connection, retrieve block numbers, and check your wallet balance. Replace with your wallet address to check balance. Use <a href="https://faucet.buildbear.io/">faucet</a> to fund with test tokens.</p><pre><code class="language-plaintext">from web3 import Web3

buildbear_url = "https://rpc.buildbear.io/prime-gorgon-3fe07045"
web3 = Web3(Web3.HTTPProvider(buildbear_url))

print(web3.is_connected())
print(web3.eth.block_number)

# Fill in your account here
balance = web3.eth.get_balance("0x9FE1b56E45c464616317eEA2663e691FbF79bE52")
print(web3.from_wei(balance, "ether"))
</code></pre><p style="margin-left:0px;">Run the Python file to get a similar output as follows:<br>&nbsp;</p><figure class="image image_resized" style="width:50%;"><img src="https://strapi.buildbear.io/uploads/sdewr_b1f7ae8cf9.png" alt="sdewr.png" srcset="https://strapi.buildbear.io/uploads/thumbnail_sdewr_b1f7ae8cf9.png 245w,https://strapi.buildbear.io/uploads/small_sdewr_b1f7ae8cf9.png 500w," sizes="100vw"></figure><h3 style="margin-left:0px;">Selling Tokens on PancakeSwap</h3><p style="margin-left:0px;">For the next part, let’s interact with the PancakeSwap router to sell tokens. We’ll connect to the PancakeSwap router contract and send a transaction to exchange tokens.</p><p style="margin-left:0px;">Use the below code to:</p><ul><li>Initialize a connection with the BuildBear RPC to access the Binance chain</li><li>Set PancakeSwap Router Contract <code>(0x10ED43C718714eb63d5aA57B78B54704E256024E</code>) for token swap operations.</li><li>Obtain PancakeSwap ABI that defines how to interact with the contract functions.</li><li>Define sender's address (The wallet holding the tokens you wish to sell) and token contract address(the token contract address you want to sell)</li></ul><p style="margin-left:0px;">Note: Check sender’s BNB native token balance. Get test tokens from faucet to pay for gas fee for executing transaction.</p><ul><li>Allow PancakeSwap to access your token by approving the <code>spend</code> amount.</li><li>Initiate Swap Transaction: Call the <code>swapExactTokensForTokens</code> or <code>swapExactTokensForETH</code> function on the PancakeSwap router contract.</li><li>Specify parameters such as the token amount to sell, the minimum tokens you want to receive, and your wallet address as the receiver.</li><li>Confirm Transaction: Monitor the transaction status and confirm once it’s complete.</li></ul><p style="margin-left:0px;"><strong>Note</strong>: Replace <code>"YOUR_PRIVATE_KEY"</code> with your actual private key for the wallet.</p><figure class="image image_resized" style="width:50%;"><img src="https://strapi.buildbear.io/uploads/carbon_7_9b86762a1a.png" alt="carbon (7).png" srcset="https://strapi.buildbear.io/uploads/thumbnail_carbon_7_9b86762a1a.png 93w,https://strapi.buildbear.io/uploads/small_carbon_7_9b86762a1a.png 298w,https://strapi.buildbear.io/uploads/medium_carbon_7_9b86762a1a.png 448w,https://strapi.buildbear.io/uploads/large_carbon_7_9b86762a1a.png 597w," sizes="100vw"></figure><p style="margin-left:0px;"><span style="background-color:rgb(255,255,255);color:rgb(23,43,77);font-family:-apple-system, BlinkMacSystemFont, &quot;Segoe UI&quot;, Roboto, Oxygen, Ubuntu, &quot;Fira Sans&quot;, &quot;Droid Sans&quot;, &quot;Helvetica Neue&quot;, sans-serif;">The output would look like:</span></p><figure class="image image_resized" style="width:50%;"><img src="https://strapi.buildbear.io/uploads/123455_002d83f351.png" alt="123455.png" srcset="https://strapi.buildbear.io/uploads/thumbnail_123455_002d83f351.png 245w,https://strapi.buildbear.io/uploads/small_123455_002d83f351.png 500w,https://strapi.buildbear.io/uploads/medium_123455_002d83f351.png 750w,https://strapi.buildbear.io/uploads/large_123455_002d83f351.png 1000w," sizes="100vw"></figure><p style="margin-left:0px;">&nbsp;</p><h3 style="margin-left:0px;">Using PancakeSwap-lottery library</h3><p style="margin-left:0px;">Let us use the <code>pancakeswap-lottery</code> library to provide access to key information in PancakeSwap's lottery contract. It can be installed from pip with the below command;</p><pre><code class="language-plaintext">pip install pancakeswap-lottery</code></pre><p style="margin-left:0px;">Now go to <a href="https://github.com/frefrik/pancakeswap-lottery/blob/main/pancakeswap_lottery/lotteryv2.py">LotteryV2</a>, and replace with your BuildBear RPC as provider. Here are some examples of what you can do:</p><h3 style="margin-left:0px;">Get stats from the current lottery round.</h3><p style="margin-left:0px;">Get the complete code from <a href="https://github.com/frefrik/pancakeswap-lottery/tree/main/pancakeswap_lottery">here</a></p><figure class="image image_resized" style="width:50%;"><img src="https://strapi.buildbear.io/uploads/829da0c6_4fc3_4b8f_92e4_707671cdfe2c_7ebf61f041.png" alt="829da0c6-4fc3-4b8f-92e4-707671cdfe2c.png" srcset="https://strapi.buildbear.io/uploads/thumbnail_829da0c6_4fc3_4b8f_92e4_707671cdfe2c_7ebf61f041.png 245w,https://strapi.buildbear.io/uploads/small_829da0c6_4fc3_4b8f_92e4_707671cdfe2c_7ebf61f041.png 500w,https://strapi.buildbear.io/uploads/medium_829da0c6_4fc3_4b8f_92e4_707671cdfe2c_7ebf61f041.png 750w,https://strapi.buildbear.io/uploads/large_829da0c6_4fc3_4b8f_92e4_707671cdfe2c_7ebf61f041.png 1000w," sizes="100vw"></figure><h3 style="margin-left:0px;">Get lottery history data (<i>Lottery Date</i>, <i>Round</i>, <i>Prize pool</i>) from the last <code>X</code> rounds.</h3><p style="margin-left:0px;">&nbsp;</p><figure class="image image_resized" style="width:50%;"><img src="https://strapi.buildbear.io/uploads/71061db1_cb11_490f_b117_9fad2e4e2c04_d3b3974447.png" alt="71061db1-cb11-490f-b117-9fad2e4e2c04.png" srcset="https://strapi.buildbear.io/uploads/thumbnail_71061db1_cb11_490f_b117_9fad2e4e2c04_d3b3974447.png 245w,https://strapi.buildbear.io/uploads/small_71061db1_cb11_490f_b117_9fad2e4e2c04_d3b3974447.png 500w,https://strapi.buildbear.io/uploads/medium_71061db1_cb11_490f_b117_9fad2e4e2c04_d3b3974447.png 750w,https://strapi.buildbear.io/uploads/large_71061db1_cb11_490f_b117_9fad2e4e2c04_d3b3974447.png 1000w," sizes="100vw"></figure><h2 style="margin-left:0px;"><br>Conclusion</h2><p style="margin-left:0px;">In this tutorial, we demonstrated how to set up a connection to BuildBear’s RPC with <code>web3.py</code>, retrieve blockchain information, and execute a token swap on PancakeSwap. With Web3.py support in BuildBear, you can simulate and automate interactions with smart contracts, analyze the results, and test your code in a controlled environment.</p><p style="margin-left:0px;">For further reading, check out <code>web3.py</code>’s <a href="https://web3py.readthedocs.io/en/stable/">official documentation</a>.<br>&nbsp;</p><p style="margin-left:0px;">&nbsp;</p><p style="margin-left:0px;">&nbsp;</p>

Screenshot from 2024-11-28 10-59-02.png

For Python developers looking to interact with Ethereum, web3.py is the go-to library. This guide shows you how to use web3.py with BuildBear RPC to test, deploy, and manage dApps effortlessly within a realistic testing environment. 

The Ultimate Guide to Web3.py for Developers

Let’s get started then, Shall we?

Let’s get started then, Shall we?

Test DApps at Scale.