如何从以太坊区块链检索数据

Question

我是区块链新手，node.js。如何使用节点获取方法从以太坊区块链检索数据。

是否可以找回原始保存的数据？

Answer 1

根据Web3 API文档，获取合约实例和调用方法的方式是：

1.合同定义

var MyContract = web3.eth.contract(abi);

2。获取地址

的合约实例

var myContractInstance = MyContract .at('0x**********');

3。执行调用

var owner = myContractInstance .owner.call();

完整代码：

var abi = [
    {
      "constant": true,
      "inputs": [],
      "name": "owner",
      "outputs": [
        {
          "name": "",
          "type": "address"
        }
      ],
      "payable": false,
      "type": "function"
    },
    {
      "inputs": [],
      "payable": false,
      "type": "constructor"
    }
  ];


var MyContract = web3.eth.contract(abi);

// initiate contract for an address
var myContractInstance = MyContract .at('0xa07ddaff6d8b7aabf91ac6f82bf89455eb9784f4');

// call constant function (synchronous way)
var owner = myContractInstance .owner.call();

console.log("owner="+owner);

工作正常：

owner=0x13a0674c16f6a5789bff26188c63422a764d9a39

如何从以太坊区块链检索数据

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