nodejs渐入佳境[10]-案例-用户输入+json增删查改

对于之前的代码进行封装

原始文件app.js

对于返回节点进行判断,如果新增了节点,就打印新增节点。

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//打印字符串
const yargs = require('yargs');
const nodes = require('./nodes.js')
console.log('Start app.');

console.log(process.argv);

console.log('yargs',yargs.argv);
const argv = yargs.argv;
var command = process.argv[2];

if(command==='add'){
 var note = nodes.addNote(argv.title,argv.body);
if(note){
console.log('add success');
console.log(`title:${note.title}`);
console.log(`body:${note.body}`);
}
}else if(command === 'list'){
nodes.getAll();

}else if(command =='read'){
nodes.getNote(argv.title);
}else if(command=='remove'){
nodes.removeNote(argv.title);
}else{
console.log('command not find');
}

notes.js:

封装 获取节点以及保存节点、返回节点。

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console.log('start nodes.js');
const fs = require('fs');

//从文件中获取节点
var fetchNode = ()=>{
try{
var notesString = fs.readFileSync('notes-data.json');
return JSON.parse(notesString);
}catch(e){
return [];
}
}
//保存节点到文件
var saveNote = (notes)=>{

fs.writeFileSync('notes-data.json',JSON.stringify(notes));

}

//增加节点,如果新增返回新增节点。
var addNote = (title,body)=>{
var notes = fetchNode();
var note = {
title,
body
};

//筛选出相同的节点
var duplicateNotes = notes.filter((note)=>note.title===title);
//没有相同的节点
if(duplicateNotes.length ===0){
notes.push(note);
saveNote(notes);
return note;
}
}

var getAll = ()=>{
console.log('Get All notes');
};

var getNote = (title)=>{

console.log('getting note',title);
};

var removeNote = (title)=>{
console.log('Removing note',title);
};

module.exports = {
addNote,
getAll,
getNote,
removeNote
};

测试

打开控制台,在当前目录下输入:

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> node app.js add --title="buy book3" --body="jonson"

控制台返回结果:

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start nodes.js
Start app.
[ '/Users/jackson/.nvm/versions/node/v10.13.0/bin/node',
'/Users/jackson/Desktop/compaign/app.js',
'add',
'--title=buy book3',
'--body=jonson' ]
yargs { _: [ 'add' ],
title: 'buy book3',
body: 'jonson',
'$0': 'app.js' }
add success
title:buy book3
body:jonson

移除节点

app.js:

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//打印字符串
const yargs = require('yargs');
const nodes = require('./nodes.js')
console.log('Start app.');

console.log(process.argv);

console.log('yargs',yargs.argv);
const argv = yargs.argv;
var command = process.argv[2];

if(command==='add'){
 var note = nodes.addNote(argv.title,argv.body);
if(note){
console.log('add success');
console.log(`title:${note.title}`);
console.log(`body:${note.body}`);
}
}else if(command === 'list'){
nodes.getAll();

}else if(command =='read'){
nodes.getNote(argv.title);
}else if(command=='remove'){
var noteRemoved = nodes.removeNote(argv.title);
var message = noteRemoved?'Note was removed':'note not found';
console.log(message);
}else{
console.log('command not find');
}

notes.js:

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console.log('start nodes.js');
const fs = require('fs');
//从文件中获取节点
var fetchNode = ()=>{
try{
var notesString = fs.readFileSync('notes-data.json');
return JSON.parse(notesString);
}catch(e){
return [];
}
}
//保存节点到文件
var saveNote = (notes)=>{

fs.writeFileSync('notes-data.json',JSON.stringify(notes));

}

//增加节点,如果新增返回新增节点。
var addNote = (title,body)=>{
var notes = fetchNode();
var note = {
title,
body
};

//筛选出相同的节点
var duplicateNotes = notes.filter((note)=>note.title===title);
//没有相同的节点
if(duplicateNotes.length ===0){
notes.push(note);
saveNote(notes);
return note;
}
}

var getAll = ()=>{
console.log('Get All notes');
};

var getNote = (title)=>{

console.log('getting note',title);
};

var removeNote = (title)=>{
var notes = fetchNode();
//筛选出不同的节点
var duplicateNotes = notes.filter((note)=>note.title!==title);
saveNote(duplicateNotes);
return notes.length !==duplicateNotes.length;
};

module.exports = {
addNote,
getAll,
getNote,
removeNote
};

测试2

打开控制台,在当前目录下输入:

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> node app.js remove --title="buy book2"

控制台返回结果并且josn文件中对应元素被移除:

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start nodes.js
Start app.
[ '/Users/jackson/.nvm/versions/node/v10.13.0/bin/node',
'/Users/jackson/Desktop/compaign/app.js',
'remove',
'--title=buy book2' ]
yargs { _: [ 'remove' ], title: 'buy book2', '$0': 'app.js' }
Note was removed

获取节点

app.js

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//打印字符串
const yargs = require('yargs');
const nodes = require('./nodes.js')
console.log('Start app.');

console.log(process.argv);

console.log('yargs',yargs.argv);
const argv = yargs.argv;
var command = process.argv[2];

if(command==='add'){
 var note = nodes.addNote(argv.title,argv.body);
if(note){
console.log('add success');
console.log(`title:${note.title}`);
console.log(`body:${note.body}`);
}
}else if(command === 'list'){
nodes.getAll();

}else if(command =='read'){
var note = nodes.getNote(argv.title);
if(note){
console.log('find');
console.log(`title:${note.title}`);
console.log(`body:${note.body}`);
}else{
console.log('note not found');
}
}else if(command=='remove'){
var noteRemoved = nodes.removeNote(argv.title);
var message = noteRemoved?'Note was removed':'note not found';
console.log(message);
}else{
console.log('command not find');
}

notes.js:

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console.log('start nodes.js');
const fs = require('fs');
//从文件中获取节点
var fetchNode = ()=>{
try{
var notesString = fs.readFileSync('notes-data.json');
return JSON.parse(notesString);
}catch(e){
return [];
}
}
//保存节点到文件
var saveNote = (notes)=>{

fs.writeFileSync('notes-data.json',JSON.stringify(notes));

}

//增加节点,如果新增返回新增节点。
var addNote = (title,body)=>{
var notes = fetchNode();
var note = {
title,
body
};

//筛选出相同的节点
var duplicateNotes = notes.filter((note)=>note.title===title);
//没有相同的节点
if(duplicateNotes.length ===0){
notes.push(note);
saveNote(notes);
return note;
}
}

var getAll = ()=>{

};

var getNote = (title)=>{

var notes = fetchNode();
//筛选出相同的节点
var duplicateNotes = notes.filter((note)=>note.title===title);
return duplicateNotes[0];
};

var removeNote = (title)=>{
var notes = fetchNode();
//筛选出不同的节点
var duplicateNotes = notes.filter((note)=>note.title!==title);
saveNote(duplicateNotes);
return notes.length !==duplicateNotes.length;
};

module.exports = {
addNote,
getAll,
getNote,
removeNote
};

测试3

打开控制台,在当前目录下输入:

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> node app.js read  --title="buy book3"

控制台返回结果:

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start nodes.js
Start app.
[ '/Users/jackson/.nvm/versions/node/v10.13.0/bin/node',
'/Users/jackson/Desktop/compaign/app.js',
'read',
'--title=buy book3',
'--body=123' ]
yargs { _: [ 'read' ], title: 'buy book3', body: 123, '$0': 'app.js' }
find
title:buy book3
body:jonson

列出所有节点

app.js

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//打印字符串
const yargs = require('yargs');
const nodes = require('./nodes.js')
console.log('Start app.');

console.log(process.argv);

console.log('yargs',yargs.argv);
const argv = yargs.argv;
var command = process.argv[2];

if(command==='add'){
 var note = nodes.addNote(argv.title,argv.body);
if(note){
console.log('add success');
console.log(`title:${note.title}`);
console.log(`body:${note.body}`);
}
}else if(command === 'list'){
var allnotes = nodes.getAll();
allnotes.forEach((note)=>{ console.log(note)});
}else if(command =='read'){
var note = nodes.getNote(argv.title);
if(note){
console.log('find');
console.log(`title:${note.title}`);
console.log(`body:${note.body}`);
}else{
console.log('note not found');
}
}else if(command=='remove'){
var noteRemoved = nodes.removeNote(argv.title);
var message = noteRemoved?'Note was removed':'note not found';
console.log(message);
}else{
console.log('command not find');
}

nodes.js

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console.log('start nodes.js');
const fs = require('fs');
//从文件中获取节点
var fetchNode = ()=>{
try{
var notesString = fs.readFileSync('notes-data.json');
return JSON.parse(notesString);
}catch(e){
return [];
}
}
//保存节点到文件
var saveNote = (notes)=>{

fs.writeFileSync('notes-data.json',JSON.stringify(notes));

}

//增加节点,如果新增返回新增节点。
var addNote = (title,body)=>{
var notes = fetchNode();
var note = {
title,
body
};

//筛选出相同的节点
var duplicateNotes = notes.filter((note)=>note.title===title);
//没有相同的节点
if(duplicateNotes.length ===0){
notes.push(note);
saveNote(notes);
return note;
}
}

var getAll = ()=>{
var notes = fetchNode();
return notes;
};

var getNote = (title)=>{

var notes = fetchNode();
//筛选出相同的节点
var duplicateNotes = notes.filter((note)=>note.title===title);
return duplicateNotes[0];
};

var removeNote = (title)=>{
var notes = fetchNode();
//筛选出不同的节点
var duplicateNotes = notes.filter((note)=>note.title!==title);
saveNote(duplicateNotes);
return notes.length !==duplicateNotes.length;
};

测试4

打开控制台,在当前目录下输入:

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> node app.js list

控制台返回结果:

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start nodes.js
Start app.
[ '/Users/jackson/.nvm/versions/node/v10.13.0/bin/node',
'/Users/jackson/Desktop/compaign/app.js',
'list' ]
yargs { _: [ 'list' ], '$0': 'app.js' }
{ title: 'buy book3', body: 'jonson' }
{ title: 'buy book2', body: 'jonson' }