About Flask-Web3

Flask-Web3 is a flask extension allowing to smoothly integrate a flask application with web3.py. This package is intended for developers will to build a Flask application that interacts with an Ethereum client.

This page gives a good introduction to Flask-Web3. If not yet install please refer to the Installation section.

It is recommended that you have some light knowledge of web3.py before you try working with Flask-Web3.

A simple example

>>> from flask import Flask, jsonify
>>> from flask_web3 import current_web3, FlaskWeb3

# Declare Flask application
>>> app = Flask(__name__)

# Set Flask-Web3 configuration
>>> app.config.update({'ETHEREUM_PROVIDER': 'http', 'ETHEREUM_ENDPOINT_URI': 'http://localhost:8545'})

# Declare Flask-Web3 extension
>>> web3 = FlaskWeb3(app=app)

# Declare route
>>> @app.route('/blockNumber')
... def block_number():
...     return jsonify({'data': current_web3.eth.blockNumber})

You can notice that Flask-Web3 gives you an application context bound variable current_web3 that is accessible from any active flask application context.

An advanced example

You may like to declare your Flask-Web3 extension from a customize Web3 class with enhanced logic.

>>> from flask import Flask, jsonify
>>> from flask_web3 import current_web3, FlaskWeb3
>>> from web3 import Web3

# Declare Flask application
>>> app = Flask(__name__)
>>> app.config.update({'ETHEREUM_PROVIDER': 'http', 'ETHEREUM_ENDPOINT_URI': 'http://localhost:8545'})

# Declare a custom Web3 class
>>> class CustomWeb3(Web3):
...     def customBlockNumber():
...         return self.eth.blockNumber

# Associate a custom FlaskWeb3 extension
>>> class CustomFlaskWeb3(FlaskWeb3):
...     web3_class = CustomWeb3

# Declare customized web3 extension
>>> web3 = CustomFlaskWeb3(app=app)
>>> isinstance(web3, CustomWeb3)
True

# Declare route
>>> @app.route('/customBlockNumber')
... def last_odd_block_number():
...     return jsonify({'data': current_web3.customBlockNumber()})

Flask-Web3 configuration

Key	Comment	Default
ETHEREUM_PROVIDER	Type of Ethereum provider to use can be one of http, ipc, ws or test	http
ETHEREUM_ENDPOINT_URI	Endpoint URI of Ethereum client (only useful when provider is http or ws)	http
ETHEREUM_IPC_PATH	IPC path of Ethereum client (only useful when provider is ipc)	None
ETHEREUM_OPTS	A dictionary containing extra options fed to the provider when declaring it	{}