Python用以太坊JSON-RPC请求对智能合约进行部署和交易

本文探讨了如何将JSON-RPC请求发送到Geth节点以创建原生的交易。目标是在使用高级库(如web3py或web3js)时了解并查看后台发生的情况。

另外,对处理错误和异常不是本文的重点。如果出现任何问题,它将只是显示失败。这篇文章主要是学习。对于生产环境,还是考虑使用web3.py。

我们将仅使用HTTP请求在私有链上使用智能合约部署和交互(调用函数和读取公共变量)。交易是离线签名的,然后才发送到geth节点进行处理。

对于本指南,我们使用的是私有的Proof-of-Authority网络。如果想创建这样一个网络,可以阅读我们以前的帖子。本文假设使用Ganache(以前称为TestRPC)或任何以太坊网络都完全没问题。因此,不会介绍有关在网络设置的任何内容,重点是使用python将HTTP请求发送到Geth节点。

条件

  • 1.通过IPC或RPC访问以太坊网络(可能是公有,私有或像Ganache这样的模拟器)。
  • 2.安装了python 3。 我个人喜欢Anaconda发行版
  • 3.安装最新版本的web3py

1.向Geth发送一个简单的请求

让我们通过向Geth发送一个非常简单的请求来热个身。查询下网络ID。 第一步是阅读文档。 我们需要的方法称为net_version,在此处进行描述。

我的Geth节点URL和端口是:http://localhost:8501。如果你使用的是具有默认值的Ganache,则URL可能是http://localhost:7545

我正在使用Requests python library来发出我的HTTP请求。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
import requests
# create persistent HTTP connection
session = requests.Session()
# as defined in https://github.com/ethereum/wiki/wiki/JSON-RPC#net_version
method = 'net_version'
params = []
payload= {"jsonrpc":"2.0",
"method":method,
"params":params,
"id":1}
headers = {'Content-type': 'application/json'}
response = session.post('http://localhost:8501', json=payload, headers=headers)
print('raw json response: {}'.format(response.json()))
print('network id: {}'.format(response.json()['result']))

结果是:

1
2
raw json response: {'id': 1, 'jsonrpc': '2.0', 'result': '1515'}
network id: 1515

不错,从那里我们准备好与合约一起部署和交易,这建立了一个良好的基础。1515是我的私有区块链的网络ID,如创世文件中所定义。目前看起来都很棒。 使用Ganache,应该获得5777的网络ID。

但在能够签署和发送交易之前,我们需要一个地址,一个私钥和一些以太币。

2.创建公钥私钥对并获取一些以太币

web3py(release 4)库将帮助我们创建密钥对。

1
2
3
4
5
6
7
import web3
w3 = web3.Web3()
myAccount = w3.eth.account.create('put some extra entropy here')
myAddress = myAccount.address
myPrivateKey = myAccount.privateKey
print('my address is : {}'.format(myAccount.address))
print('my private key is : {}'.format(myAccount.privateKey.hex()))

在这个示例中,我得到:

1
2
my address is    : 0xF464A67CA59606f0fFE159092FF2F474d69FD675
my private key is: 0x94cb9f766ef067eb229da85213439cf4cbbcd0dc97ede9479be5ee4b7a93b96f

请永远不要分享你的私钥!我这样做是因为它是一个本地私有链,我每天都要销毁并重启几次。我没有在任何公共网络上使用这个密钥对。

现在为了获得这个地址,有多种方法:

1.一种非常简单的方法是在genesis.json文件中添加此地址并启动新网络。下面是之前我的创世纪文件,其中包括我们刚刚创建的地址(删除0x)。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
{
"config": {
"chainId": 1515,
"homesteadBlock": 1,
"eip150Block": 2,
"eip150Hash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"eip155Block": 3,
"eip158Block": 3,
"byzantiumBlock": 4,
"clique": {
"period": 5,
"epoch": 30000
}
},
"nonce": "0x0",
"timestamp": "0x5a722c92",
"extraData": "0x000000000000000000000000000000000000000000000000000000000000000008a58f09194e403d02a1928a7bf78646cfc260b087366ef81db496edd0ea2055ca605e8686eec1e60000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
"gasLimit": "0x8000000",
"difficulty": "0x1",
"mixHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"coinbase": "0x0000000000000000000000000000000000000000",
"alloc": {
"08a58f09194e403d02a1928a7bf78646cfc260b0": {
"balance": "0x200000000000000000000000000000000000000000000000000000000000000"
},
"87366ef81db496edd0ea2055ca605e8686eec1e6": {
"balance": "0x200000000000000000000000000000000000000000000000000000000000000"
},
"F464A67CA59606f0fFE159092FF2F474d69FD675": {
"balance": "0x200000000000000000000000000000000000000000000000000000000000000"
}
},
"number": "0x0",
"gasUsed": "0x0",
"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000"
}

2.如果你有可以挖矿的节点或ganache,请打开Geth Javascript控制台并手动创建交易:

1
2
3
4
5
6
7
8
9
$ geth attach ipc:'http://localhost:8501' // 7545 for ganache
Welcome to the Geth JavaScript console!
instance: Geth/v1.7.3-stable-4bb3c89d/linux-amd64/go1.9
coinbase: 0x87366ef81db496edd0ea2055ca605e8686eec1e6
at block: 1585 (Wed, 14 Feb 2018 11:46:04 CET)
modules: eth:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0
> eth.sendTransaction({'from':eth.coinbase, 'to':'0xF464A67CA59606f0fFE159092FF2F474d69FD675', 'value':1000000000000000000000})
"0xdbc86acbe3644ac2cdb68132bbeecda40733c10f07ca16d87a2e5001e50eec4c"
> exit

这里我从0x87366...发送1000以太币到我的地址0xF464A...,1个以太坊是10的18次方wei(1个后跟18个零)。值的单位是wei。

3.在公共测试链上,使用faucet。

3.使用智能合约部署和交易

太好了,既然我们有一个带有一些以太网的地址(为了支付gas费用),我们可以离线创建我们的交易,签名并将其发送到具有原生JSON-RPC的HTTP请求节点。

我们将使用send_rawTransaction方法,该方法将交易的签名作为输入参数。

python代码正在查询truffle在编译智能合约时创建的包含合约abi和字节码的json文件。在测试python代码之前,创建一个truffle工作区并编译虚拟合约AdditionContract.sol

1
2
3
$ truffle init
// add the smart contract in contracts/
$ truffle compile

然后更新python代码,用geth节点的URL以及truffle工作空间和genesis文件的路径(不要忘记在路径中用你的userName替换我的userName)。

其他一切都在代码中,应该是不言自明的。

1
2
3
4
5
6
7
8
9
10
11
12
13
pragma solidity ^0.4.18;

contract AdditionContract {
uint public state = 0;

function add(uint value1, uint value2) public {
state = value1 + value2;
}

function getState() public constant returns (uint) {
return state;
}
}

文末附完整代码。

我们让一切都变得简单易于修改和测试。 玩的开心 :)

python用web3.py库开发以太坊来说非常的方便,有兴趣的用户可以关注我们的python以太坊教程,主要是针对python工程师使用web3.py进行区块链以太坊开发的详解。

另外其他语言可以学习的以太坊教程如下:

  • web3j教程,主要是针对java和android程序员进行区块链以太坊开发的web3j详解。
  • 以太坊教程,主要介绍智能合约与dapp应用开发,适合入门。
  • 以太坊开发,主要是介绍使用node.js、mongodb、区块链、ipfs实现去中心化电商DApp实战,适合进阶。
  • php以太坊,主要是介绍使用php进行智能合约开发交互,进行账号创建、交易、转账、代币开发以及过滤器和事件等内容。
  • C#以太坊,主要讲解如何使用C#开发基于.Net的以太坊应用,包括账户管理、状态与交易、智能合约开发与交互、过滤器和事件等。

汇智网原创翻译,转载请标明出处。这里是原文

raw_JSON_RPC_requests_to_smart_contract.py

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
# associated medium post: https://medium.com/@ethervolution/ethereum-create-raw-json-rpc-requests-with-python-for-deploying-and-transacting-with-a-smart-7ceafd6790d9
import requests
import json
import web3 # Release 4.0.0-beta.8
import pprint
import time

# create persistent HTTP connection
session = requests.Session()
w3 = web3.Web3()
pp = pprint.PrettyPrinter(indent=2)

requestId = 0 # is automatically incremented at each request

URL = 'http://localhost:8501' # url of my geth node
PATH_GENESIS = '/home/salanfe/privateNetworks/geth_PoA/genesis.json'
PATH_SC_TRUFFLE = '/home/salanfe/Projects/AdditionContract/' # smart contract path

# extracting data from the genesis file
genesisFile = json.load(open(PATH_GENESIS))
CHAINID = genesisFile['config']['chainId']
PERIOD = genesisFile['config']['clique']['period']
GASLIMIT = int(genesisFile['gasLimit'],0)

# compile your smart contract with truffle first
truffleFile = json.load(open(PATH_SC_TRUFFLE + '/build/contracts/AdditionContract.json'))
abi = truffleFile['abi']
bytecode = truffleFile['bytecode']

# Don't share your private key !
myAddress = '0xF464A67CA59606f0fFE159092FF2F474d69FD675' # address funded in genesis file
myPrivateKey = '0x94cb9f766ef067eb229da85213439cf4cbbcd0dc97ede9479be5ee4b7a93b96f'


''' =========================== SOME FUNCTIONS ============================ '''
# see http://www.jsonrpc.org/specification
# and https://github.com/ethereum/wiki/wiki/JSON-RPC

def createJSONRPCRequestObject(_method, _params, _requestId):
return {"jsonrpc":"2.0",
"method":_method,
"params":_params, # must be an array [value1, value2, ..., valueN]
"id":_requestId}, _requestId+1

def postJSONRPCRequestObject(_HTTPEnpoint, _jsonRPCRequestObject):
response = session.post(_HTTPEnpoint,
json=_jsonRPCRequestObject,
headers={'Content-type': 'application/json'})

return response.json()


''' ======================= DEPLOY A SMART CONTRACT ======================= '''
### get your nonce
requestObject, requestId = createJSONRPCRequestObject('eth_getTransactionCount', [myAddress, 'latest'], requestId)
responseObject = postJSONRPCRequestObject(URL, requestObject)
myNonce = w3.toInt(hexstr=responseObject['result'])
print('nonce of address {} is {}'.format(myAddress, myNonce))

### create your transaction
transaction_dict = {'from':myAddress,
'to':'', # empty address for deploying a new contract
'chainId':CHAINID,
'gasPrice':1, # careful with gas price, gas price below the --gasprice option of Geth CLI will cause problems. I am running my node with --gasprice '1'
'gas':2000000, # rule of thumb / guess work
'nonce':myNonce,
'data':bytecode} # no constrctor in my smart contract so bytecode is enough

### sign the transaction
signed_transaction_dict = w3.eth.account.signTransaction(transaction_dict, myPrivateKey)
params = [signed_transaction_dict.rawTransaction.hex()]

### send the transacton to your node
requestObject, requestId = createJSONRPCRequestObject('eth_sendRawTransaction', params, requestId)
responseObject = postJSONRPCRequestObject(URL, requestObject)
transactionHash = responseObject['result']
print('contract submission hash {}'.format(transactionHash))

### wait for the transaction to be mined and get the address of the new contract
while(True):
requestObject, requestId = createJSONRPCRequestObject('eth_getTransactionReceipt', [transactionHash], requestId)
responseObject = postJSONRPCRequestObject(URL, requestObject)
receipt = responseObject['result']
if(receipt is not None):
if(receipt['status'] == '0x1'):
contractAddress = receipt['contractAddress']
print('newly deployed contract at address {}'.format(contractAddress))
else:
pp.pprint(responseObject)
raise ValueError('transacation status is "0x0", failed to deploy contract. Check gas, gasPrice first')
break
time.sleep(PERIOD/10)


''' ================= SEND A TRANSACTION TO SMART CONTRACT ================'''
### get your nonce
requestObject, requestId = createJSONRPCRequestObject('eth_getTransactionCount', [myAddress, 'latest'], requestId)
responseObject = postJSONRPCRequestObject(URL, requestObject)
myNonce = w3.toInt(hexstr=responseObject['result'])
print('nonce of address {} is {}'.format(myAddress, myNonce))

### prepare the data field of the transaction
# function selector and argument encoding
# https://solidity.readthedocs.io/en/develop/abi-spec.html#function-selector-and-argument-encoding
value1, value2 = 10, 32 # random numbers here
function = 'add(uint256,uint256)' # from smart contract
methodId = w3.sha3(text=function)[0:4].hex()
param1 = (value1).to_bytes(32, byteorder='big').hex()
param2 = (value2).to_bytes(32, byteorder='big').hex()
data = '0x' + methodId + param1 + param2

transaction_dict = {'from':myAddress,
'to':contractAddress,
'chainId':CHAINID,
'gasPrice':1, # careful with gas price, gas price below the threshold defined in the node config will cause all sorts of issues (tx not bieng broadcasted for example)
'gas':2000000, # rule of thumb / guess work
'nonce':myNonce,
'data':data}

### sign the transaction
signed_transaction_dict = w3.eth.account.signTransaction(transaction_dict, myPrivateKey)
params = [signed_transaction_dict.rawTransaction.hex()]

### send the transacton to your node
print('executing {} with value {},{}'.format(function, value1, value2))
requestObject, requestId = createJSONRPCRequestObject('eth_sendRawTransaction', params, requestId)
responseObject = postJSONRPCRequestObject(URL, requestObject)
transactionHash = responseObject['result']
print('transaction hash {}'.format(transactionHash))

### wait for the transaction to be mined
while(True):
requestObject, requestId = createJSONRPCRequestObject('eth_getTransactionReceipt', [transactionHash], requestId)
responseObject = postJSONRPCRequestObject(URL, requestObject)
receipt = responseObject['result']
if(receipt is not None):
if(receipt['status'] == '0x1'):
print('transaction successfully mined')
else:
pp.pprint(responseObject)
raise ValueError('transacation status is "0x0", failed to deploy contract. Check gas, gasPrice first')
break
time.sleep(PERIOD/10)



''' ============= READ YOUR SMART CONTRACT STATE USING GETTER =============='''
# we don't need a nonce since this does not create a transaction but only ask
# our node to read it's local database

### prepare the data field of the transaction
# function selector and argument encoding
# https://solidity.readthedocs.io/en/develop/abi-spec.html#function-selector-and-argument-encoding
# state is declared as public in the smart contract. This creates a getter function
methodId = w3.sha3(text='state()')[0:4].hex()
data = '0x' + methodId
transaction_dict = {'from':myAddress,
'to':contractAddress,
'chainId':CHAINID,
'data':data}

params = [transaction_dict, 'latest']
requestObject, requestId = createJSONRPCRequestObject('eth_call', params, requestId)
responseObject = postJSONRPCRequestObject(URL, requestObject)
state = w3.toInt(hexstr=responseObject['result'])
print('using getter for public variables: result is {}'.format(state))



''' ============= READ YOUR SMART CONTRACT STATE GET FUNCTIONS =============='''
# we don't need a nonce since this does not create a transaction but only ask
# our node to read it's local database

### prepare the data field of the transaction
# function selector and argument encoding
# https://solidity.readthedocs.io/en/develop/abi-spec.html#function-selector-and-argument-encoding
# state is declared as public in the smart contract. This creates a getter function
methodId = w3.sha3(text='getState()')[0:4].hex()
data = '0x' + methodId
transaction_dict = {'from':myAddress,
'to':contractAddress,
'chainId':CHAINID,
'data':data}

params = [transaction_dict, 'latest']
requestObject, requestId = createJSONRPCRequestObject('eth_call', params, requestId)
responseObject = postJSONRPCRequestObject(URL, requestObject)
state = w3.toInt(hexstr=responseObject['result'])
print('using getState() function: result is {}'.format(state))


''' prints
nonce of address 0xF464A67CA59606f0fFE159092FF2F474d69FD675 is 4
contract submission hash 0x64fc8ce5cbb5cf822674b88b52563e89f9e98132691a4d838ebe091604215b25
newly deployed contract at address 0x7e99eaa36bedba49a7f0ea4096ab2717b40d3787
nonce of address 0xF464A67CA59606f0fFE159092FF2F474d69FD675 is 5
executing add(uint256,uint256) with value 10,32
transaction hash 0xcbe3883db957cf3b643567c078081343c0cbd1fdd669320d9de9d05125168926
transaction successfully mined
using getter for public variables: result is 42
using getState() function: result is 42
'''