javascript - 将 localForage 与 Cordova 结合使用的正确方法是什么？

Question

我正在尝试使用localForage与 localForage-cordovaSQLiteDriver在 cordova 应用程序中设置持久存储。它不起作用，我不断将以下条目记录到控制台:

我不确定我是否正确理解 localforage 生命周期。这就是我所拥有的:

// 1) setup cordova SQL lite driver
localforage.defineDriver(window.cordovaSQLiteDriver).then(function() {

    // 2) set preferred driver order
    return localforage.setDriver([
        window.cordovaSQLiteDriver._driver, // <-- prefer cordovaSQLiteDriver
        localforage.INDEXEDDB,
        localforage.WEBSQL,
        localforage.LOCALSTORAGE
    ]);
})
.then(function() {
    // 3) wait for localForage to be ready
    return localforage.ready();
})
.then(function() {

    // 4) create a globally scoped app database
    window.appStorage = localforage.createInstance({
        version: 1.0,
        size: 52428800, // 50mb
        name: 'my-app-name',
        storeName: 'setup'
    });

    // 5) check if we're using cordova sql lite
    if (localforage.driver() !== window.cordovaSQLiteDriver._driver) {
        console.warn('Not using cordovaSQLiteDriver.');
    }

    // 6) write something
    return appStorage.setItem('message', 'It worked!'); // <-- only it doesn't 
})
.then(function() {
    // 7) get the value back out of the database
    return appStorage.getItem('message');
})
.then(function(message){
    // 8) write the value to the console
    console.log(message);
});

在我看来，它应该将它成功了!打印到控制台。

Answer 1

因此，首先，createInstance() 返回一个全新且不相关的 localforage 实例，并从头开始重新初始化。因此，新实例将尝试使用默认驱动程序首选项顺序(IndexedDB、WebSQL、LocalStorage)来决定使用哪个驱动程序。所有 localforage 实例共享的唯一内容是可用/定义的驱动程序。所以你可以做这样的事情:

localforage.defineDriver(window.cordovaSQLiteDriver).then(function() {
    window.appStorage = localforage.createInstance({
        version: 1.0,
        size: 52428800, // 50mb
        name: 'my-app-name',
        storeName: 'setup',
        driver: [
            window.cordovaSQLiteDriver._driver, // <-- prefer cordovaSQLiteDriver
            localforage.INDEXEDDB,
            localforage.WEBSQL,
            localforage.LOCALSTORAGE
        ]
        // OR instead of passing the `driver` option,
        // you can call `window.appStorage.setDriver()`
        // right after `createInstance()`
    });

    if (window.appStorage.driver() !== window.cordovaSQLiteDriver._driver) {
        console.warn('Not using cordovaSQLiteDriver before setItem.');
    }

    return appStorage.setItem('message', 'It worked!');
})
.then(function() {
    return appStorage.getItem('message');
})
.then(function(message){
    console.log(message);
    if (window.appStorage.driver() !== window.cordovaSQLiteDriver._driver) {
        console.warn('Not using cordovaSQLiteDriver after setItem.');
    }
});