The common entry point for interacting with the Web3.py library is the Web3 object. Web3 objects provide apis for Python-developed applications to interact with the Ethereum blockchain, typically by connecting to a JSON-RPC server.

Will the provider

Providers connect Web3 to the blockchain. The web3.py library comes with the following built-in providers, which can be used in most use cases.

  • web3.HTTPProvider: Used to connect to JSON-RPC servers based on HTTP and HTTPS.
  • web3.IPCProvider: Used to connect to jSON-RPC servers based on IPC sockets.
  • web3.WebsocketProviderJson-rpc server for connecting to WS – and WSS – based Websockets

HTTPProvider: Used to get the full URI where the server can be found. For local development, this is similar to http://localhost:8545.

IPCProvider: Used to get the file system path where the IPC socket can be found. If no arguments are provided, it uses the default path of the operating system.

WebsocketProvider: Used to get the full URI where the server can be found. For local development, this is similar to ws://127.0.0.1:8546.

Example code is as follows:

>>> from web3 import Web3, HTTPProvider, IPCProvider, WebsocketProvider # Note that you should create only one RPCProvider per # process, as it recycles underlying TCP/IP network connections between # your process and Ethereum node >>> web3 = Web3(HTTPProvider('http://localhost:8545')) # or for an IPC based connection >>> web3 = Web3(IPCProvider()) # or for Websocket Based Connection >>> web3 = web3 (WebsocketProvider('ws://127.0.0.1:8546'))Copy the code

Basic API

The Web3 class provides the following handy basic apis:

Type conversion

web3.toHex

Web3.toHex(primitive=None, hexstr=None, text=None)
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Takes various input and returns it in hexadecimal representation. It follows the rules for converting to hexadecimal in the JSON-RPC specification.

>>> Web3.toHex(0) '0x0' >>> Web3.toHex(1) '0x1' >>> Web3.toHex(0x0) '0x0' >>> Web3.toHex(0x000F) '0xf' >>> Web3.toHex(b'') '0x' >>> Web3.toHex(b'\x00\x0F') '0x000f' >>> Web3.toHex(False) '0x0' >>> Web3.toHex(True) '0x1' >>> Web3.toHex(hexstr='0x000F') '0x000f' >>> Web3.toHex(hexstr='000F') '0x000f' >>> Web3.toHex(text='') '0x' >>> = 'cowmo' Web3. ToHex (text) '0 x636f776dc3b6'Copy the code

web3.toText

Web3.toText(primitive=None, hexstr=None, text=None)
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Takes various inputs and returns their string equivalents. The text is decoded to UTF-8.

>>> web3.totext (0x636F776dc3B6) 'cowmo' >>> web3.totext (b'cowm\xc3\ XB6 ') 'cowmo' >>> Web3.totext (hexstr='0x636f776dc3b6') 'cowmo' >>> web3.totext (hexstr='636f776dc3b6') 'cowmo' >>> = 'cowmo' Web3. ToText (text) 'cowmo'Copy the code

Web3.toBytes

Web3.toBytes(primitive=None, hexstr=None, text=None)
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Takes various inputs and returns the equivalent bytes. The text is encoded as UTF-8.

>>> Web3.toBytes(0) b'\x00' >>> Web3.toBytes(0x000F) b'\x0f' >>> Web3.toBytes(b'') b'' >>> Web3.toBytes(b'\x00\x0F') b'\x00\x0f' >>> Web3.toBytes(False) b'\x00' >>> Web3.toBytes(True) b'\x01' >>> Web3.toBytes(hexstr='0x000F') b'\x00\x0f' > > > Web3. ToBytes (hexstr = '000 f) b' \ x00 \ x0f '> > > Web3. ToBytes (text =' ') "> b > > Web3. ToBytes (text = 'cowmo') b'cowm\xc3\xb6'Copy the code

Web3.toInt

Web3.toInt(primitive=None, hexstr=None, text=None)
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Takes various inputs and returns their integer equivalents.

>>> Web3.toInt(0)
0
>>> Web3.toInt(0x000F)
15
>>> Web3.toInt(b'\x00\x0F')
15
>>> Web3.toInt(False)
0
>>> Web3.toInt(True)
1
>>> Web3.toInt(hexstr='0x000F')
15
>>> Web3.toInt(hexstr='000F')
15
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Currency conversion

Web3.toWei

Web3.toWei(value, currency)
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Returns the value converted to wei in the denomination specified by the currency argument.

>>> Web3.toWei(1, 'ether')
1000000000000000000
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Web3.fromWei

Web3.fromWei(value, currency)
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Returns the value of wei converted to the given currency. The value is returned as Decimal to ensure accuracy down to WEI.

>>> web3.fromWei(1000000000000000000, 'ether')
Decimal('1')
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address

Web3.isAddress

Web3.isAddress(value)
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Returns true if the value is one of the recognized address formats. – Allows 0x prefixes and values without prefixes. – If the address contains mixed upper and lower case characters, the function also checks whether the address is EIP55 compliant.

>>> web3.isAddress('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
True
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Web3.isChecksumAddress

Web3.isChecksumAddress(value)
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Returns true if the value conforms to EIP55 and is a valid address

>>> web3.isChecksumAddress('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
True
>>> web3.isChecksumAddress('0xd3cda913deb6f67967b99d67acdfa1712c293601')
False
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Web3.toChecksumAddress

Web3.toChecksumAddress(value)
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Returns the given address with EIP55 checksum.

>>> Web3.toChecksumAddress('0xd3cda913deb6f67967b99d67acdfa1712c293601')
'0xd3CdA913deB6f67967B99D67aCDFa1712C293601'
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Cryptographic hash

Web3.sha3

classmethod Web3.sha3(primitive=None, hexstr=None, text=None)
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Returns Keccak SHA256 for the given value. Before calculating the hash, the text is encoded into UTF-8, just like solidity. Any of the following ways are valid and equal:

>>> Web3.sha3(0x747874)
>>> Web3.sha3(b'\x74\x78\x74')
>>> Web3.sha3(hexstr='0x747874')
>>> Web3.sha3(hexstr='747874')
>>> Web3.sha3(text='txt')
HexBytes('0xd7278090a36507640ea6b7a0034b69b0d240766fa3f98e3722be93c613b29d2e')
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Web3.soliditySha3

classmethod Web3.soliditySha3(abi_types, value)

Returns Sha3, which is evaluated by the soliditySha3 function based on the supplied value and abi_types. Abi_types should be a list of solidity type strings for each value provided.

>>> Web3.soliditySha3(['bool'], True)
HexBytes("0x5fe7f977e71dba2ea1a68e21057beebb9be2ac30c6410aa38d4f3fbe41dcffd2")

>>> Web3.soliditySha3(['uint8', 'uint8', 'uint8'], [97, 98, 99])
HexBytes("0x4e03657aea45a94fc7d47ba826c8d667c0d1e6e33a64a036ec44f58fa12d6c45")

>>> Web3.soliditySha3(['uint8[]'], [[97, 98, 99]])
HexBytes("0x233002c671295529bcc50b76a2ef2b0de2dac2d93945fca745255de1a9e4017e")

>>> Web3.soliditySha3(['address'], ["0x49eddd3769c0712032808d86597b84ac5c2f5614"])
HexBytes("0x2ff37b5607484cd4eecf6d13292e22bd6e5401eaffcc07e279583bc742c68882")

>>> Web3.soliditySha3(['address'], ["ethereumfoundation.eth"])
HexBytes("0x913c99ea930c78868f1535d34cd705ab85929b2eaaf70fcd09677ecd6e5d75e9")
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Module Modules

Web3.py splits the JSON-RPC functionality over modules that loosely correspond to namespaces for jSON-RPC methods.

For those who want to get started quickly on developing Ethereum in Python, check out this: Python Ethereum, a detailed explanation of blockchain ethereum development for Python engineers using Web3.py.

Other Ethereum related tutorials:

  • Web3j tutorial, mainly for Java and Android programmers for blockchain Ethereum development web3J details.
  • Ethereum tutorial, mainly introduces smart contract and DAPP application development, suitable for getting started.
  • Ethereum development, mainly introduces the use of Node.js, mongodb, blockchain, IPFS to achieve decentralized e-commerce DApp combat, suitable for advanced.
  • PHP Ethereum mainly introduces the use of PHP for smart contract development interaction, account creation, transactions, transfers, token development, filters and events and other content.

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