YDN-DB - 删除数据库，然后在页面加载/重新加载时重新创建和加载，但在刷新时不加载

Posted 2023-05-09

【中文标题】YDN-DB - 删除数据库，然后在页面加载/重新加载时重新创建和加载，但在刷新时不加载

【英文标题】：YDN-DB - Delete DB then recreate and load when page is loaded/reloaded but not when refreshed

【发布时间】：2016-10-07 22:10:36

【问题描述】：

我正在转换一些 IndexedDB 代码以使用 YDN-DB，并且需要一些帮助来转换它。如果页面已加载或重新加载，则此代码实质上会删除 DB，但在刷新时不会。 我将如何使用 YDN-DB 实现这一目标？

var indexedDB = window.indexedDB || window.webkitIndexedDB || window.mozIndexedDB || window.msIndexedDB;
var db;
window.refreshing = false;

$(document).ready(function()
    if(window.performance)  
        if(performance.navigation.type  == 0 ) 
            // The db already exists so delete it and re-create it so we don't have stale records.
            deleteDB(); 
         else 
            window.refreshing = true;
            open();
        
    
);

function deleteDB() 
    var request = indexedDB.deleteDatabase("DocsDB");
    request.onsuccess = function() 
        open();
    
    request.onerror = function(event) 
        throw "Error in deleteDB.";
    


function open() 
    var request = indexedDB.open("DocsDB");
    var upgraded = false;
    request.onupgradeneeded = function(evt) 
        upgraded = true;
        var dbnew = evt.target.result;

        dbnew.onerror = function(event) 
            console.log("IndexedDB error: " + evt.target.error.code);
        ;

        var objectStore = dbnew.createObjectStore(
                 "docs",  keyPath: "id", autoIncrement: true );

        objectStore.createIndex("docname",   "DOC_NAME",    unique: false );
        objectStore.createIndex("printdate", "PRINT_DATE",  unique: false );
    
    request.onsuccess = function(evt) 
        db = request.result;
        if (!upgraded && !window.refreshing) 
            throw "Not upgraded";
        
        request.result.onversionchange = function(e) 
            if (e.newVersion === null)  // An attempt is made to delete the db
                e.target.close(); // Manually close our connection to the db
            
        ;

        if(typeof db != 'undefined' && !window.refreshing) 
            // We load the store with the records here, attempting to add records via ajax doesn't work
            // looks like we'll ahve to load them via ajax before initialization?
            var store = getObjectStore(db);
            for (i=0; i<documents["Rows"].length-1;i++) 
                store.add(documents["Rows"][i]);
            
        
    
    request.onerror = function() 
        throw "Error in open";
    


 function getObjectStore(db, mode = 'readwrite') 
     if(typeof db != 'undefined') 
         var tx = db.transaction('docs', mode);
         return tx.objectStore('docs');
     else 
        return null;
    
 

【参考方案1】：

要删除数据库使用，ydn.db.deleteDatabase("DocsDB")。

【讨论】：

是的，我知道该怎么做，但是是否有一个事件，例如 onsuccess 用于删除数据库后能够调用 open() ？

好的，在文档中找到了 .done() / .fail() 承诺。正在尝试使用 .onsuccess() / .onerror() 将发布一个示例供您与您的库一起使用。

我将修改后的示例添加到您的 GitHub 存储库上的票证中。 github.com/yathit/ydn-db/issues/105