DApp教程：用Truffle 开发一个链上记事本

** 照着做完了，很好的文章！** 补充一点，js控制台报Cannot read property 'constructor' of undefined的话把address类型加个name

event NewNote(address spender, string note);

你好，大神：1,请问getNotes: function() {...}中的App.account不存在，怎么获取？ 2，另外这句代码少了一个）,$("#notes").append( '<div > <textarea >' + note + '</textarea></div>' ;

请到问答提问

请问下，智能合约的助记词/私钥要如何保管才不会泄露？

一样的问题，楼主怎末解决的

truffle.js换成了truffle_config.js，我是这样写的：

var HDWalletProvider = require("truffle-hdwallet-provider");

var mnemonic = "orange apple banana orange2 apple2 banana2 orange3 apple3 banana3 orange4 apple4 banana4"; 。。。。 在下面这句里，提示找不到：mnemonic return new HDWalletProvider(mnemonic, "https://ropsten.infura.io/v3/b5a2f156624f457ca4fa970f2447588e");

App.noteInstance.addNote($("#new_note").val()).then(function(result) { return App.watchChange(); }).catch(function (err) { console.log(err.message); --------- 添加的时候, 返回地址错误 });

App.account是怎么取到的?

App.watchChange(); 这个函数在哪里?

这个问题解决了嘛

web3.eth.defaultAccount = web3.eth.accounts[0]; 。。。

大神好,请教个错误,谢谢 D:\solutions\truffle\dapp\NoteOnChain\node_modules\eth-block-tracker\src\polling.js:51 const newErr = new Error(PollingBlockTracker - encountered an error while attempting to update latest block:\n${err.stack}) ^ Error: PollingBlockTracker - encountered an error while attempting to update latest block: undefined at PollingBlockTracker._performSync (D:\solutions\truffle\dapp\NoteOnChain\node_modules\eth-block-tracker\src\polling.js:51:24) at processTicksAndRejections (node:internal/process/task_queues:96:5)

问下需要多少测试币啊,我1个eth不够

请问这种链上记事本是不是也会消耗gas，相当于付费记录？

完整代码如下：

NoteContract.sol 修改了构造函数

pragma solidity ^0.5.0;

contract NoteContract {
    mapping(address => string [] ) public notes;

    constructor() public {
    }

    event NewNote(address sender, string note);

    function addNote( string memory note) public {
        notes[msg.sender].push(note);
        emit NewNote(msg.sender, note);
    }
    event ModifyNote(address, uint index);

    function modifyNote(address own, uint index, string memory note) public {
        require(own == msg.sender);
	notes[own][index] = note;
        emit ModifyNote(own, index);
    }

    function getNotesLen(address own) public view returns (uint) {
        return notes[own].length;
    }
}

app.js 添加了account字段，设置默认账户，添加watchChange方法，修复了append右括号丢失的问题

App = {
	web3Provider: null,
	contracts: {},
	account: {},

	init: async function() {
		return await App.initWeb3();
	},

	initWeb3: async function() {
		// 最新dapp 浏览器或MetaMask
		if (window.ethereum) {
			App.web3Provider = window.ethereum;
			try {
				// 请求账号授权
				await window.ethereum.enable();
			} catch (error) {
				// User denied account access...
				console.error("User denied account access")
			}
		}
		// Legacy dapp browsers...
		else if (window.web3) {
			App.web3Provider = window.web3.currentProvider;
		} else {
			App.web3Provider = new Web3.providers.HttpProvider('http://localhost:9545');
		}
		web3 = new Web3(App.web3Provider);
		web3.eth.defaultAccount = web3.eth.accounts[0];
		App.account = web3.eth.defaultAccount;
		return App.initContract();
	},

	initContract: function() {
		$.getJSON('NoteContract.json', function(data) {
			App.contracts.noteContract = TruffleContract(data);
			App.contracts.noteContract.setProvider(App.web3Provider);

			App.contracts.noteContract.deployed()
				.then(function(instance) {
					App.noteIntance = instance;
					return App.getNotes();
				});
		});
		return App.bindEvents();
	},
	getNotes: function() {
		App.noteIntance.getNotesLen(App.account)
			.then(function(len) {
				App.noteLength = len;
				if (len > 0) {
					App.loadNote(len - 1);
				}
			})
			.catch(function(err) {});
	},
	loadNote: function(index) {
		App.noteIntance.notes(App.account, index)
			.then(function(note) {
				$("#notes")
					.append('<div> <textarea>' + note + '</textarea></div>');
				if (index - 1 >= 0) {
					App.loadNote(index - 1);
				}
			})
			.catch(function(err) {});
	},
	bindEvents: function() {
		$("#add_new")
			.on('click', function() {
				$("#loader")
					.show();
				App.noteIntance.addNote($("#new_note")
						.val())
					.then(function(result) {
						return App.watchChange();
					})
					.catch(function(err) {
						console.log(err.message);
					});
			});
	},
	watchChange: function() {
		location.reload();
	},
};

$(function() {
	$(window)
		.load(function() {
			App.init();
		});
});

完整代码如下：

NoteContract.sol 修改了构造函数

pragma solidity ^0.5.0;
contract NoteContract { mapping(address => string [] ) public notes;

constructor() public {
}

event NewNote(address sender, string note);

function addNote( string memory note) public {
    notes[msg.sender].push(note);
    emit NewNote(msg.sender, note);
}
event ModifyNote(address, uint index);

function modifyNote(address own, uint index, string memory note) public {
    require(own == msg.sender);
notes[own][index] = note;
    emit ModifyNote(own, index);
}

function getNotesLen(address own) public view returns (uint) {
    return notes[own].length;
}
}

app.js 添加了account字段，设置默认账户，添加watchChange方法，修复了append右括号丢失的问题

App = {
    web3Provider: null,
    contracts: {},
    account: {},

    init: async function() {
        return await App.initWeb3();
    },

    initWeb3: async function() {
        // 最新dapp 浏览器或MetaMask
        if (window.ethereum) {
            App.web3Provider = window.ethereum;
            try {
                // 请求账号授权
                await window.ethereum.enable();
            } catch (error) {
                // User denied account access...
                console.error("User denied account access")
            }
        }
        // Legacy dapp browsers...
        else if (window.web3) {
            App.web3Provider = window.web3.currentProvider;
        } else {
            App.web3Provider = new Web3.providers.HttpProvider('http://localhost:9545');
        }
        web3 = new Web3(App.web3Provider);
        web3.eth.defaultAccount = web3.eth.accounts[0];
        App.account = web3.eth.defaultAccount;
        return App.initContract();
    },

    initContract: function() {
        $.getJSON('NoteContract.json', function(data) {
            App.contracts.noteContract = TruffleContract(data);
            App.contracts.noteContract.setProvider(App.web3Provider);

            App.contracts.noteContract.deployed()
                .then(function(instance) {
                    App.noteIntance = instance;
                    return App.getNotes();
                });
        });
        return App.bindEvents();
    },
    getNotes: function() {
        App.noteIntance.getNotesLen(App.account)
            .then(function(len) {
                App.noteLength = len;
                if (len > 0) {
                    App.loadNote(len - 1);
                }
            })
            .catch(function(err) {});
    },
    loadNote: function(index) {
        App.noteIntance.notes(App.account, index)
            .then(function(note) {
                $("#notes")
                    .append('<div> <textarea>' + note + '</textarea></div>');
                if (index - 1 >= 0) {
                    App.loadNote(index - 1);
                }
            })
            .catch(function(err) {});
    },
    bindEvents: function() {
        $("#add_new")
            .on('click', function() {
                $("#loader")
                    .show();
                App.noteIntance.addNote($("#new_note")
                        .val())
                    .then(function(result) {
                        return App.watchChange();
                    })
                    .catch(function(err) {
                        console.log(err.message);
                    });
            });
    },
    watchChange: function() {
        location.reload();
    },
};

$(function() {
    $(window)
        .load(function() {
            App.init();
        });
});