web3.pyについて解説！Pythonを使ってスマートコントラクトの関数を呼び出してみよう！

ウマたん

当サイト【スタビジ】の本記事では、web3.pyについて解説していきます！web3.pyを利用することでスマートコントラクトに記載された関数を呼び出してデータを取得したりスマートコントラクトをデプロイしたりできるんです！Web3領域ではJavascriptを利用することが多いですがPythonも使えるんです！

こんにちは！

データサイエンティストのウマたん(@statistics1012)です！

この記事ではスマートコントラクトに記載された関数を呼び出してデータを取得したりスマートコントラクトをデプロイできるweb3.pyについて解説していきます！

Web3領域はJavascriptを利用することが多いですが、Pythonを利用することもできるのです！

web3.pyのインポートと接続

まずは、web3.pyのインポートと接続をおこなっていきます。

from web3 import Web3

続いてinfuraというサービスを使ってHTTP接続するイーサリアムのネットワークを作成していきます。

まずアカウントを登録を済ませて、ダッシュボード画面からCREATE NEW API KEYで新しいAPI KEYを作成します。

作成したAPI KEYの画面からEthereumのネットワークをコピーします。

ネットワークに接続していきます。以下のように記述しましょう！

web3 = Web3(Web3.HTTPProvider('＜作成したネットワークアドレス＞'))

接続ができているか以下のように記述します。

web3.is_connected()

Trueと返ってきたら成功です！

web3.pyを使って特定のNFTのスマートコントラクトの関数呼び出し

それでは、接続が確認できたので、実際に流通しているNFTのスマートコントラクトの関数を呼び出してデータを見ていきましょう！

今回見てみるのはNFTの中で最も有名と言っても過言ではないBAYC（BoredApeYachtClub）！

ただの変哲もないサルの画像ですが・・・

まず、こいつの情報を確認するためにetherscanというサイトのBAYCのページへ行きます。

etherscanとはイーサリアムのネットワークに載っているトランザクションや保有状況などを確認できるサイトです。

このサイトからBAYCのaddressとabiを取得します。

addressはコントラクトのアドレスであり、仮想通貨を送る上でのウォレットも一意のアドレスを持っています。

以下から取得できます。

abiはコントラクトの関数情報を含んだJSONファイルです。

まずContactに行き

以下から取得できます。

取得したaddressとabiを以下のように記載しておきましょう！

address = "0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D"
abi = json.loads('[{"inputs":[{"internalType":"string","name":"name","type":"string"},{"internalType":"string","name":"symbol","type":"string"},{"internalType":"uint256","name":"maxNftSupply","type":"uint256"},{"internalType":"uint256","name":"saleStart","type":"uint256"}],"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"owner","type":"address"},{"indexed":true,"internalType":"address","name":"approved","type":"address"},{"indexed":true,"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"owner","type":"address"},{"indexed":true,"internalType":"address","name":"operator","type":"address"},{"indexed":false,"internalType":"bool","name":"approved","type":"bool"}],"name":"ApprovalForAll","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"previousOwner","type":"address"},{"indexed":true,"internalType":"address","name":"newOwner","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"from","type":"address"},{"indexed":true,"internalType":"address","name":"to","type":"address"},{"indexed":true,"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"Transfer","type":"event"},{"inputs":[],"name":"BAYC_PROVENANCE","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"MAX_APES","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"REVEAL_TIMESTAMP","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"apePrice","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"approve","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"baseURI","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"emergencySetStartingIndexBlock","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"flipSaleState","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"getApproved","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"address","name":"operator","type":"address"}],"name":"isApprovedForAll","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"maxApePurchase","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"numberOfTokens","type":"uint256"}],"name":"mintApe","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[],"name":"name","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"owner","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"ownerOf","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"renounceOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"reserveApes","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"from","type":"address"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"safeTransferFrom","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"from","type":"address"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"tokenId","type":"uint256"},{"internalType":"bytes","name":"_data","type":"bytes"}],"name":"safeTransferFrom","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"saleIsActive","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"operator","type":"address"},{"internalType":"bool","name":"approved","type":"bool"}],"name":"setApprovalForAll","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"string","name":"baseURI","type":"string"}],"name":"setBaseURI","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"string","name":"provenanceHash","type":"string"}],"name":"setProvenanceHash","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"revealTimeStamp","type":"uint256"}],"name":"setRevealTimestamp","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"setStartingIndex","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"startingIndex","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"startingIndexBlock","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"bytes4","name":"interfaceId","type":"bytes4"}],"name":"supportsInterface","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"symbol","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"index","type":"uint256"}],"name":"tokenByIndex","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"uint256","name":"index","type":"uint256"}],"name":"tokenOfOwnerByIndex","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"tokenURI","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"totalSupply","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"from","type":"address"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"tokenId","type":"uint256"}],"name":"transferFrom","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"withdraw","outputs":[],"stateMutability":"nonpayable","type":"function"}]')

続いてこのaddressとabiを用いてcontractにアクセスしていきます。

contract = web3.eth.contract(address=address, abi=abi)

このコントラクトから関数を呼び出していきます。

コントラクトに記述されている関数はetherscanのContractのRead Contractという箇所から確認できます。

以下のように記述してあげましょう！

print(contract.functions.totalSupply().call())
print(contract.functions.name().call())

以下のように返ってくると思います。

BAYCの総発行量は10000なのでtotalSupplyは10000であり、nameではBAYCに正式名料が返ってきていることが分かりますね！

web3.py　まとめ

ここまでで、web3.pyについてまとめてきました！

ブロックチェーン上のオンチェーン分析に関しては当メディアが運営している学習サービス「スタアカ」の以下のコースで学べるので興味のある方は是非チェックしてみてください！

スタアカは業界最安級のAIデータサイエンススクールです。

AIデータサイエンスを学んで市場価値の高い人材になりましょう！

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