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047 孤荷凌寒从零开始学区块链第 47 天 DAPP002

941xue · 于 发布 · 74 次阅读

孤荷凌寒自学第133天
区块链第47天,Dapp002
【主要内容】
今天继续学习实战,做一个真正的依托于智能合约的DAPP。今天继续学习直接使用Js代码与metaMask钱包来互动完成合约的访问。共耗时58分钟。
(此外整理作笔记花费了约82分钟)
详细学习过程见文末学习过程屏幕录像。
参照学习的博文是:
https://www.ucloud.cn/yun/24154.html

【ABI的JS文件】
首先也完成了一个abi接口的JS文件。
cryptozombies_abi.js
内容如下:

//cryptozombiesABI 变量存储的是一个列表,连接合约API接口的
var cryptozombiesABI =[
    {
        "constant": false,
        "inputs": [],
        "name": "acceptOwnership",
        "outputs": [],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": false,
        "inputs": [
            {
                "name": "_addr",
                "type": "address"
            }
        ],
        "name": "addLock",
        "outputs": [
            {
                "name": "success",
                "type": "bool"
            }
        ],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": false,
        "inputs": [
            {
                "name": "_spender",
                "type": "address"
            },
            {
                "name": "_value",
                "type": "uint256"
            }
        ],
        "name": "approve",
        "outputs": [
            {
                "name": "success",
                "type": "bool"
            }
        ],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": false,
        "inputs": [
            {
                "name": "_newOwner",
                "type": "address"
            }
        ],
        "name": "changeOwner",
        "outputs": [],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": false,
        "inputs": [
            {
                "name": "_enable",
                "type": "bool"
            }
        ],
        "name": "disableLock",
        "outputs": [
            {
                "name": "success",
                "type": "bool"
            }
        ],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": false,
        "inputs": [
            {
                "name": "_enable",
                "type": "bool"
            }
        ],
        "name": "enableTransfer",
        "outputs": [
            {
                "name": "success",
                "type": "bool"
            }
        ],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": false,
        "inputs": [
            {
                "name": "_addr",
                "type": "address"
            }
        ],
        "name": "removeLock",
        "outputs": [
            {
                "name": "success",
                "type": "bool"
            }
        ],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": false,
        "inputs": [
            {
                "name": "_addr",
                "type": "address"
            },
            {
                "name": "_enable",
                "type": "bool"
            }
        ],
        "name": "setExclude",
        "outputs": [
            {
                "name": "success",
                "type": "bool"
            }
        ],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": false,
        "inputs": [
            {
                "name": "_to",
                "type": "address"
            },
            {
                "name": "_value",
                "type": "uint256"
            }
        ],
        "name": "transfer",
        "outputs": [
            {
                "name": "success",
                "type": "bool"
            }
        ],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": false,
        "inputs": [
            {
                "name": "_from",
                "type": "address"
            },
            {
                "name": "_to",
                "type": "address"
            },
            {
                "name": "_value",
                "type": "uint256"
            }
        ],
        "name": "transferFrom",
        "outputs": [
            {
                "name": "success",
                "type": "bool"
            }
        ],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "inputs": [],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "constructor"
    },
    {
        "anonymous": false,
        "inputs": [
            {
                "indexed": false,
                "name": "_prevOwner",
                "type": "address"
            },
            {
                "indexed": false,
                "name": "_newOwner",
                "type": "address"
            }
        ],
        "name": "OwnerUpdate",
        "type": "event"
    },
    {
        "anonymous": false,
        "inputs": [
            {
                "indexed": true,
                "name": "_from",
                "type": "address"
            },
            {
                "indexed": true,
                "name": "_to",
                "type": "address"
            },
            {
                "indexed": false,
                "name": "_value",
                "type": "uint256"
            }
        ],
        "name": "Transfer",
        "type": "event"
    },
    {
        "anonymous": false,
        "inputs": [
            {
                "indexed": true,
                "name": "_owner",
                "type": "address"
            },
            {
                "indexed": true,
                "name": "_spender",
                "type": "address"
            },
            {
                "indexed": false,
                "name": "_value",
                "type": "uint256"
            }
        ],
        "name": "Approval",
        "type": "event"
    },
    {
        "constant": true,
        "inputs": [
            {
                "name": "_owner",
                "type": "address"
            },
            {
                "name": "_spender",
                "type": "address"
            }
        ],
        "name": "allowance",
        "outputs": [
            {
                "name": "remaining",
                "type": "uint256"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    },
    {
        "constant": true,
        "inputs": [
            {
                "name": "",
                "type": "address"
            }
        ],
        "name": "balanceOf",
        "outputs": [
            {
                "name": "",
                "type": "uint256"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    },
    {
        "constant": true,
        "inputs": [],
        "name": "decimals",
        "outputs": [
            {
                "name": "",
                "type": "uint8"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    },
    {
        "constant": true,
        "inputs": [],
        "name": "name",
        "outputs": [
            {
                "name": "",
                "type": "string"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    },
    {
        "constant": true,
        "inputs": [],
        "name": "owner",
        "outputs": [
            {
                "name": "",
                "type": "address"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    },
    {
        "constant": true,
        "inputs": [],
        "name": "symbol",
        "outputs": [
            {
                "name": "",
                "type": "string"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    },
    {
        "constant": true,
        "inputs": [],
        "name": "totalSupply",
        "outputs": [
            {
                "name": "",
                "type": "uint256"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    },
    {
        "constant": true,
        "inputs": [],
        "name": "transferEnabled",
        "outputs": [
            {
                "name": "",
                "type": "bool"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    }
]

【Html文件内容】

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>CryptoZombies front-end</title>
    <script language="javascript" type="text/javascript" src="jquery.min.js"></script>
    <script language="javascript" type="text/javascript" src="web3.min.js"></script>
    <!-- 1. Include cryptozombies_abi.js here -->
    <script language="javascript" type="text/javascript" src="cryptozombies_abi.js"></script>

    <script>
            //声明一些钱包地址:
            //下面一行定义的是部署合约的节点(创世节点)的信息,公钥
            var wallet_address="0x5227C3EF48B5A1bcF784593e46D9579D26a3b592"; //狐狸钱包的公钥,就是钱包地址,是eth网络上的一个节点。
            //下面一行定义的是节点2的信息
            var w2add="0xe2d6c2f289c53B5aEA44C47293Ba179a3bfa21f0"; //公钥

            //下面一行定义的是节点3 的信息
            var w3add="0xb40599fB0366DCf0ffe86677b005b3f20Dfa29aE"; //公钥

            //下面一行定义的是节点4 的信息
            var w4add="0x70c8461366d5368B1E79CBFc2Acf4ba56C745977"; //公钥




            // 2. Start code here
            var cc;
            var web3js;

            function startApp() {
                try {
                    var cryptoZombiesAddress = "0xf89074dcdd8798b7e20b8cd88a9a38f27479411c"; //要连接的合约地址
                    cc = web3js.eth.contract(cryptozombiesABI, cryptoZombiesAddress); //如果是另一个版本可能还得加上new关键字。


                } catch (err) {
                    alert(err);
                }
                alert("加载成功");

            }

            window.addEventListener('load', function () {

                // Checking if Web3 has been injected by the browser (Mist/MetaMask)
                if (typeof web3 !== 'undefined') {
                    // Use Mist/MetaMask's provider自动使用网页钱包的节点,不用自己指定节点。
                    web3js = new Web3(web3.currentProvider);
                    alert(web3js.version.api);
                } else {
                    // Handle the case where the user doesn't have Metamask installed
                    // Probably show them a message prompting them to install Metamask
                    alert("请安装Metamask钱包");
                }

                // Now you can start your app & access web3 freely:
                startApp();

            })

            //----------------下面是自定义的与合约交互的函数-------------------------
            //--查询一个节点授权另一个节点可以运用的代币的授权余额数
            function getAllowance(owneradd,spenderadd){
                try{
                    //cc.methods.allowance(owneradd,spenderadd).call({from: currentAccount}, function(error, result){
                    //    if(!error) {
                    //        alert(result);
                    //    } else {
                    //        alert(error);
                    //    }
                    //});
                    //return "ok";
                    return cc.methods.allowance(owneradd,spenderadd).call();


                }catch(err){
                    return '在尝试调用合约的查询授权节点可用余额时出错 :' + err;
                }
            }



            //--------------------------调用测试---------------------------------------
            //--查询节点一向节点二授权的代币余额
            function cmdone_click(){
                try{
                    r=getAllowance(wallet_address,w2add);
                    alert(r);
                    //getAllowance(wallet_address,w2add)
                    //.then(function(result) {
                    //    alert("allowbanlanced is: " + JSON.stringify(result));
                    //});//这儿不管使用then,还是done都报错。
                }catch(err){
                    alert(err)
                }
            }


        </script>

</head>
<body>
    <div>
        <input type="button" value="查询授权全额" id="cmdone" name="cmdone" onclick="cmdone_click();" />

    </div>

</body>
</html>

【卡住的问题】
今天前面部分非常顺利,但截止当前仍然没有确定是否用js代码顺利连接上了合约,因为在执行:

return cc.methods.allowance(owneradd,spenderadd).call();

语句时,卡住,直接提示:
TypeError: Cannot read property 'allowance' of undefined
经多方搜索,未来找到有效答案,于是我怀疑,此处也许合约并没有连接并调用成功。
也恳请高手给予指导,万分感激。

github: https://github.com/lhghroom/Self-learning-blockchain-from-scratch
原文地址:https://www.941xue.com/content.aspx?id=1550

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