更新版本時如何清除來自indexedDB的所有數據？

我有兩個問題： 1.我想當我更新我的數據庫版本清除所有數據。更新版本時如何清除來自indexedDB的所有數據？

objectStore.clear();

，但我有錯誤： main1.js：42未捕獲ConstraintError：無法執行對「IDBDatabase」 createObjectStore「：具有指定名稱的對象存儲已經存在。

更新版本DB如何僅向我的Db添加新項目？

var browserDatabase = {};

browserDatabase._db = null; 
browserDatabase._dbVersion = 4; 
browserDatabase._dbName = "mediaStorageDB"; 
browserDatabase._storeName = "myStore"; 
var idb = window.indexedDB 

var IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction; 
var IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange; 

var dbName='nameDb'; 

if (!window.indexedDB) { 
    // window.alert("Ваш браузер не поддерживат стабильную версию IndexedDB. Такие-то функции будут недоступны"); 
} 
var request = window.indexedDB.open("MyTestDatabase", 7); 


request.onupgradeneeded = function(e) { 

    console.log(e.oldVersion) 

    db = event.target.result; 
    //console.log(db) 
    // Создаем хранилище объектов для этой базы данных 
    // var objectStore = db.createObjectStore("name", { keyPath: "myKey" }) 
    const customerData = [ 
     { ssn: "444-44-4444", name: "Bill", age: 35, email: "[email protected]" }, 
     { ssn: "555-55-5555", name: "Donna", age: 32, email: "[email protected]" } 
    ]; 



    var objectStore = db.createObjectStore("customers", { keyPath: "ssn" }); 

    // Create an index to search customers by name. We may have duplicates 
    // so we can't use a unique index. 
    objectStore.createIndex("name", "name", { unique: false }); 

    // Create an index to search customers by email. We want to ensure that 
    // no two customers have the same email, so use a unique index. 
    objectStore.createIndex("email", "email", { unique: true }); 


    objectStore.clear(); //clear previous version 



    // Store values in the newly created objectStore. 
    for (var i in customerData) { 
     objectStore.add(customerData[i]); 
    } 

    if (e.oldVersion < 1) { 
     // create v1 schema 
    } 
    if (e.oldVersion < 2) { 
     // upgrade v1 to v2 schema 
    } 
    if (e.oldVersion < 3) { 
     // upgrade v2 to v3 schema 
    } 
    // ... 
}; 
request.onerror = function(event) { 
    // Сделать что-то при ошибке request.errorCode! 
    console.log('error'); 
    console.log(event); 
}; 
request.onsuccess = function(event) { 
    // Выполнить какой-то код если запрос успешный request.result! 
    console.log('success'); 

    db = event.target.result; 
    console.log(db); 

    var transaction = db.transaction(["customers"], "readwrite"); 


    const customerData = [ 
     { ssn: "888-44-4444", name: "Sasga", age: 35, email: "[email protected]" }, 
     { ssn: "99-55-5555", name: "Andrii", age: 32, email: "[email protected]" } 
    ]; 
    var objectStore = transaction.objectStore("customers"); 
    for (var i in customerData) { 
     var request = objectStore.add(customerData[i]); 
     request.onsuccess = function(event) { 
      // event.target.result == customerData[i].ssn; 
     }; 
    } 


    transaction.oncomplete = function(event) { 
     console.log("All done!"); 
    }; 

    transaction.onerror = function(event) { 
     // Don't forget to handle errors! 
    }; 


};

來源

2017-03-03 zloctb

clear將在商店中刪除所有數據。

deleteObjectStore將刪除該商店。

由於商店已經存在並且您正在嘗試創建該商店，因此您會收到錯誤消息。如果您希望能夠運行create，則必須先運行deleteObjectStore。

然而，這可能不是你想要做的。在版本更改中，您通常不想刪除對象存儲庫，索引和數據。你只是想更新它們。

來源

2017-03-06 04:05:55 dumbmatter

更新版本時如何清除來自indexedDB的所有數據？

回答

相關問題