12.《Electron 跨平台开发实战》- chapter12 IndexedDB

IndexedDB
第三方访问 IndexedDB
- idb库
- Dexie.js
Clipsmater-IndexedDB
- 项目：Clipsmater-IndexedDB
- 完整代码

IndexedDB

IndexedDB 是由Chromeinu提供的NoSQL数据库，它的键和值可以是任何类型的JavaScript类型

第三方访问 IndexedDB

与IndexedDB 的所有交互都是异步进行的，直接使用事件来实现异步处理，这导致代码难以阅读和理解，

idb库

github:https://github.com/jakearchibald/idb
idb库封装了IndexedDB的内部细节，将IndexedDb基于事件的API封装成了一个基于Promise的API

Dexie.js

github:https://github.com/dfahlander/Dexie.js
electron中使用示例： https://github.com/dfahlander/Dexie.js/tree/master/samples/electron
API简单使用：https://dexie.org/docs/API-Reference

Clipsmater-IndexedDB

项目：Clipsmater-IndexedDB

使用IndexedDB数据库存储剪切板内容，使用第三方库 Dexie.js 操作IndexedDB数据库

完整代码

package.json

{
  "name": "clipmaster-9000",
  "version": "1.0.0",
  "description": "A menubar application with a rich UI.",
  "main": "app/main.js",
  "scripts": {
    "start": "electron .",
    "test": "echo "Error:no test specified" && exit 1"
  },
  "author": "weikai",
  "license": "MIT",
  "dependencies": {
    "dexie": "^3.0.1",
    "electron": "9.0.3",
    "menubar": "^9.0.1",
    "request": "^2.88.2"
  }
}

安装第三方库dexie

  cnpm install dexie --save

自定义数据库模块 dbdexie.js

创建dbdexie.js文件，内容如下：

const Dexie = require('dexie');
const db = new Dexie('clipsmarter_database');

db.version(1).stores({
    clips: '++id, value, data'
});

module.exports = db;

创建一个名为clipsmarter_database的数据，
创建数据库表clips, 其中：

NOTE: Don’t declare all columns like in SQL. You only declare properties you want to index, that is properties you want to use in a where(…) query.
Schema Syntax

++ Auto-incremented primary key
& Unique
- ```
Multi-entry index
```
[A+B] Compound index.

使用 dexie

引用自定模块 `dbdexie`

const db = require('./dbdexie');

查询

const initClippingElement = () => {
  /*
  db.clips
    //.reverse() //按主键降序排列
    .each(clip => {
      let clippingElement = createClippingElement(clip.id, clip.value);
      clippingsList.prepend(clippingElement);
    });
*/
  db.clips
    .orderBy('id')
    //.reverse()  //按主键降序排列
    .toArray((clips) => {
      for (var clip of clips) {
        let clippingElement = createClippingElement(clip.id, clip.value);
        clippingsList.prepend(clippingElement);
      }
    });
}

html中设置clipId

const createClippingElement = (clipId, clippingText) => {
  const clippingElement = document.createElement('article');

  clippingElement.classList.add('clippings-list-item');

  clippingElement.innerHTML = `
    <div class="clipping-text" disabled="true"></div>
    <div class="clipping-controls">
      <button class="copy-clipping">&rarr; Clipboard</button>
      <button class="publish-clipping">Publish</button>
      <button class="remove-clipping" data-clipId='${clipId}'>Remove</button>
    </div>
  `;

  clippingElement.querySelector('.clipping-text').innerText = clippingText;

  return clippingElement;
};

添加

const addClippingToList = () => {
  const clippingText = clipboard.readText();
  db.clips.add({ value: clippingText, data: Date.now() })
    .then(id => {
      return db.clips.get(id);
    }).then(item => {
      const clippingElement = createClippingElement(item.id, item.value);
      clippingsList.prepend(clippingElement);
    }).catch(err => {
      alert("Error: " + (err.stack || err));
    });
};

删除

删除时，获取id: `let clipId = parseInt(event.target.getAttribute("data-clipId"));`


clippingsList.addEventListener('click', (event) => {
  const hasClass = className => event.target.classList.contains(className);
  let clipId = parseInt(event.target.getAttribute("data-clipId")); //删除时，获取id
  const clippingListItem = getButtonParent(event);

  if (hasClass('remove-clipping')) removeClipping(clipId, clippingListItem);
  if (hasClass('copy-clipping')) writeToClipboard(getClippingText(clippingListItem));
  if (hasClass('publish-clipping')) publishClipping(getClippingText(clippingListItem));
});

const removeClipping = (clipId, target) => {
  db.clips.delete(clipId).then(result => {
    //Promise that resolves successfully with an undefined result, no matter if a record was deleted or not. 
    //不管删没删，都是返回：undefined
    target.remove();
  });
};

renderer.js 完整代码

const { clipboard, ipcRenderer, shell } = require('electron');
const db = require('./dbdexie');

let baseUrl = 'https://api.github.com/gists';
const request = require('request').defaults({
  url: baseUrl,
  headers: { 'User-Agent': 'Clipmaster 9000' }
});

const clippingsList = document.getElementById('clippings-list');
const copyFromClipboardButton = document.getElementById('copy-from-clipboard');

ipcRenderer.on('create-new-clipping', () => {
  addClippingToList();
  new Notification('Clipping Added', {
    body: `${clipboard.readText()}`
  });
});

ipcRenderer.on('write-to-clipboard', () => {
  const clipping = clippingsList.firstChild;
  writeToClipboard(getClippingText(clipping));
  new Notification('Clipping Copied', {
    body: `${clipboard.readText()}`
  });
});

ipcRenderer.on('publish-clipping', () => {
  const clipping = clippingsList.firstChild;
  publishClipping(getClippingText(clipping));
});

const initClippingElement = () => {
  /*
  db.clips
    //.reverse() //按主键降序排列
    .each(clip => {
      let clippingElement = createClippingElement(clip.id, clip.value);
      clippingsList.prepend(clippingElement);
    });
*/
  db.clips
    .orderBy('id')
    //.reverse()  //按主键降序排列
    .toArray((clips) => {
      for (var clip of clips) {
        let clippingElement = createClippingElement(clip.id, clip.value);
        clippingsList.prepend(clippingElement);
      }
    });
}

const createClippingElement = (clipId, clippingText) => {
  const clippingElement = document.createElement('article');

  clippingElement.classList.add('clippings-list-item');

  clippingElement.innerHTML = `
    <div class="clipping-text" disabled="true"></div>
    <div class="clipping-controls">
      <button class="copy-clipping">&rarr; Clipboard</button>
      <button class="publish-clipping">Publish</button>
      <button class="remove-clipping" data-clipId='${clipId}'>Remove</button>
    </div>
  `;

  clippingElement.querySelector('.clipping-text').innerText = clippingText;

  return clippingElement;
};

const addClippingToList = () => {
  const clippingText = clipboard.readText();
  db.clips.add({ value: clippingText, data: Date.now() })
    .then(id => {
      return db.clips.get(id);
    }).then(item => {
      const clippingElement = createClippingElement(item.id, item.value);
      clippingsList.prepend(clippingElement);
    }).catch(err => {
      alert("Error: " + (err.stack || err));
    });
};

copyFromClipboardButton.addEventListener('click', addClippingToList);

clippingsList.addEventListener('click', (event) => {
  const hasClass = className => event.target.classList.contains(className);
  let clipId = parseInt(event.target.getAttribute("data-clipId"));
  const clippingListItem = getButtonParent(event);

  if (hasClass('remove-clipping')) removeClipping(clipId, clippingListItem);
  if (hasClass('copy-clipping')) writeToClipboard(getClippingText(clippingListItem));
  if (hasClass('publish-clipping')) publishClipping(getClippingText(clippingListItem));
});

const removeClipping = (clipId, target) => {
  db.clips.delete(clipId).then(result => {
    //Promise that resolves successfully with an undefined result, no matter if a record was deleted or not. 
    //不管删没删，都是返回：undefined
    target.remove();
  });
};

const writeToClipboard = (clippingText) => {
  clipboard.writeText(clippingText);
};

const publishClipping = (clippingText) => {

  request.post(baseUrl, toJSON(clippingText), (err, response, body) => {

    if (err) {
      return new Notification('Error Publishing Your Clipping', {
        body: JSON.parse(err).message
      });
    }

    const gistUrl = JSON.parse(body).documentation_url; //   const gistUrl = JSON.parse(body).html_url;
    const notification = new Notification('Your Clipping Has Been Published', {
      body: `Click to open ${gistUrl} in your browser.`
    });

    notification.onclick = () => { shell.openExternal(gistUrl); };

    clipboard.writeText(gistUrl);
  });

};

const getButtonParent = ({ target }) => {
  return target.parentNode.parentNode;
};

const getClippingText = (clippingListItem) => {
  return clippingListItem.querySelector('.clipping-text').innerText;
};

const toJSON = (clippingText) => {
  return {
    body: JSON.stringify({
      description: 'Created with Clipmaster 9000',
      public: 'true',
      files: {
        'clipping.txt': { content: clippingText }
      }
    })
  };
};

initClippingElement();

main.html
main.html 没做任何变化，沿用charp-10的内容

<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width,initial-scale=1">
  <title>Clipmaster 9000</title>
  <link rel="stylesheet" href="style.css" type="text/css">
</head>

<body>
  <div class="container">
    <section class="controls">
      <button id="copy-from-clipboard">Copy from Clipboard</button>
    </section>

    <section class="content">
      <div id="clippings-list" class="clippings-list"></div>
    </section>
  </div>
  <script>
    require('./renderer.js');
  </script>
</body>

</html>

main,js


const { menubar } = require('menubar');
const { globalShortcut, Menu } = require('electron');

const mb = menubar({
  preloadWindow: true,
  browserWindow: {
    webPreferences: {
      nodeIntegration: true
    },

  },
  index: `file://${__dirname}/index.html`,
});


mb.on('ready', () => {
  const secondaryMenu = Menu.buildFromTemplate([
    {
      label: 'Quit',
      click() { mb.app.quit(); },
      accelerator: 'CommandOrControl+Q'
    },
  ]);

  mb.tray.on('right-click', () => {
    mb.tray.popUpContextMenu(secondaryMenu);
  });

  const createClipping = globalShortcut.register('CommandOrControl+!', () => {
    mb.window.webContents.send('create-new-clipping');
  });

  const writeClipping = globalShortcut.register('CmdOrCtrl+Alt+@', () => {
    mb.window.webContents.send('write-to-clipboard');
  });

  const publishClipping = globalShortcut.register('CmdOrCtrl+Alt+#', () => {
    mb.window.webContents.send('publish-clipping');
  });

  if (!createClipping) { console.error('Registration failed', 'createClipping'); }
  if (!writeClipping) { console.error('Registration failed', 'writeClipping'); }
  if (!publishClipping) { console.error('Registration failed', 'publishClipping'); }

});

style.css

html {
  box-sizing: border-box;
}

html, body {
  height: 100%;
   100%;
  overflow: hidden;
  font-size: 12px;
}

*, *:before, *:after {
  box-sizing: inherit;
}

body {
  margin: 0;
  padding: 0;
}

body, input {
  font: menu;
  font-size: 12px;
}

body > div {
  height: 100%;
  overflow: scroll;
  -webkit-overflow-scrolling: touch;
}

.container {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  overflow: auto;
}

textarea, input, div, button { outline: none; }

.controls {
  background-color: rgb(217, 241, 238);
  padding: 1em;
  top: 0;
  position: fixed;
   100%;
}

.controls button {
  background-color: rgb(181, 220, 216);
  border: none;
  padding: 0.5em 1em;
}

.controls button:hover {
  background-color: rgb(156, 198, 192);
}

.controls button:active {
  background-color: rgb(144, 182, 177);
}

.controls button:disabled {
  background-color: rgb(196, 204, 202);
}

.content {
  height: 100%;
}

.clippings-list {
  margin-top: 65px;
  padding: 0 10px;
}

.clippings-list-item {
  border: 1px solid rgb(178, 193, 191);
  box-shadow: 1px 1px 1px 1px rgba(205, 228, 224, 0.78);
  padding: 0.5em;
  margin-bottom: 1em;
}

.clipping-text {
  background-color: rgb(228, 248, 245);
  padding: 0.5em;
  min- 100%;
  max-height: 10em;
  overflow: scroll;
}

.clipping-text::-webkit-scrollbar {
  display: none;
}

.clipping-controls {
  margin-top: 0.5em;
}

button {
  background-color: rgb(181, 220, 216);
  border: none;
  font-size: 0.8em;
  padding: 0.5em 1em;
}

button:hover {
  background-color: rgb(156, 198, 192);
}

button:active {
  background-color: rgb(144, 182, 177);
}

button:disabled {
  background-color: rgb(196, 204, 202);
}

button.remove-clipping {
  display: none;
  float: right;
  color: white;
  background-color: rgb(208, 69, 55);
}

button.remove-clipping:hover {
  background-color: rgb(208, 41, 29);
}

button.remove-clipping:active {
  background-color: rgb(236, 0, 6);
}

button.remove-clipping:disabled {
  background-color: rgb(152, 73, 64);
}

.clippings-list-item:hover button.remove-clipping {
  display: inline-block;
}

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原文地址：https://www.cnblogs.com/easy5weikai/p/13167807.html