Question

我正在尝试更改solidity的状态变量值，并在geth控制台上进行测试，但状态变量的值不会更改。步骤如下：

1：写一个简单的智能合约代码，如下所示

pragma solidity ^0.4.0;

contract SimpleStorage {

uint public storedData=99;
mapping(string => uint)  balances;



function set(uint x) public returns (uint){

    storedData = x;
    return storedData;

}

function get() public constant returns (uint) {

    return storedData;

}

function multiply(uint a) returns(uint d) {
    return a * 7;
}

function setmapping(string key,uint value) returns(uint v)
{
     balances[key] = value;
     return balances[key];
}

function getmapping(string key) returns(uint v)
{
    return balances[key];
}

function kill()
{ 

}


}

2：用松露编译代码，使用命令

truffle compile

3：启动geth，解锁帐户，然后启动minner

4：部署智能合约

truffle migration --reset

然后我看到控制台输出如下

Using network 'development'.
Running migration: 1_initial_migration.js
Replacing Migrations...
... 0x8ccf9e1599c2760ff3eed993be10929403e1faa05489a247a067f4f06536c74c
Migrations: 0xec08113a9e810e527d99a1aafa8376425c4a75ed
Saving successful migration to network...
... 0xedbf12715b736759e9d9297cbaaeb3151d95f478c2f1ee71bff4819d2dbb47e5
Saving artifacts...
Running migration: 2_deploy_contracts.js
Replacing SimpleStorage...
... 0xff5b00f9b14d8ecea4828c3ad8e9dbfa9d685bc0b81530fc346759d7998b060f
SimpleStorage: 0x96cf1e076f4d99a5d0823bd76c8de6a3a209d125
Saving successful migration to network...
... 0x3452a9e76b73e250de80874ebc3fd454724ebf6a15563bee0d5ba89b7b41909f
Saving artifacts...

这意味着智能合约已成功部署

5：然后在geth控制台中，我将abi变量设置如下：

abi=[{"constant":true,"inputs":[],"name":"storedData","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"changeStorage","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"kill","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"getAll","outputs":[{"name":"","type":"uint256"},{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"x","type":"uint256"}],"name":"set","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"get","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"key","type":"string"},{"name":"value","type":"uint256"}],"name":"setmapping","outputs":[{"name":"v","type":"uint256"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"refrenceType","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"changeMemory","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"key","type":"string"}],"name":"getmapping","outputs":[{"name":"v","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"a","type":"uint256"}],"name":"multiply","outputs":[{"name":"d","type":"uint256"}],"payable":false,"type":"function"}]

6：立即获得合同：

test=eth.contract(abi).at("0x2f3970e8e4e2f5ed4ccb37b0f79fe5598700e2f0")

7：运行set（）

test.set.call(22);

输出是22，我认为状态变量storedData已成功设置为新值22，但当我在代码下运行以读取storedData时，

test4.get()

返回值仍然是99，这意味着storedData的值没有改变，除了使用uint做测试之外，我也试过了映射，但答案和uint一样，我不知道是否我在某个地方错了，或者状态变量不允许被修改，任何人都可以帮助我吗？

感谢。

Answer 1

从问题来看，这是不改变状态的呼叫：

test.set.call(22)

要更改状态，您必须发出交易。 call(...)仅告诉您如果要发送交易会发生什么。有关更多背景信息，请参阅：What is the difference between a transaction and a call?

所以你可以用以下代码替换上面的行：

test.set.sendTransaction(22)

或者，web3.js将automatically attempt决定是使用交易还是通话。所以在这种情况下你可以简单地使用：

test.set(22)

有关web3.js如何决定的更多背景信息，请参阅：How does web3.js decide to run a call() or sendTransaction() on a method call?

可靠性，将值设置为状态变量，值未更改

1 个答案: