javascript 错误“在不允许突变的数据库上尝试了突变操作。” 在 indexedDB 中检索数据时
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Error "A mutation operation was attempted on a database that did not allow mutations." when retrieving data in indexedDB
提问by Aleksandr Motsjonov
I have this simple example code:
我有这个简单的示例代码：
var request = mozIndexedDB.open('MyTestDatabase');
request.onsuccess = function(event){
var db = event.target.result;
var request = db.setVersion('1.0');
request.onsuccess = function(event){
console.log("Success version.");
if(!db.objectStoreNames.contains('customers')){
console.log("Creating objectStore");
db.createObjectStore('customers', {keyPath: 'ssn'});
}
var transaction = db.transaction([], IDBTransaction.READ_WRITE, 2000);
transaction.oncomplete = function(){
console.log("Success transaction");
var objectStore = transaction.objectStore('customers');
};
};
};
I am getting this:
我得到这个：
A mutation operation was attempted on a database that did not allow mutations." code: "6
试图在不允许突变的数据库上进行突变操作。”代码：“6
on line
在线的
var objectStore = transaction.objectStore('customers');
Can't figure out - what do I do wrong?
想不通 - 我做错了什么？
采纳答案by Aleksandr Motsjonov
I think I found the answer. I shouldn't access objectStore inside oncomplete. I just need to do it after making new transaction. Right way is this:
我想我找到了答案。我不应该在 oncomplete 中访问 objectStore。我只需要在进行新交易后做。正确的做法是这样的：
var transaction = db.transaction([], IDBTransaction.READ_WRITE, 2000);
transaction.oncomplete = function(){
console.log("Success transaction");
};
var objectStore = transaction.objectStore('customers');
Btw, this is how exactly Mozilla's MDN shows. https://developer.mozilla.org/en/IndexedDB/Using_IndexedDB#section_10
顺便说一句，这正是 Mozilla 的 MDN 显示的方式。https://developer.mozilla.org/en/IndexedDB/Using_IndexedDB#section_10
回答by cyong
You can create or delete an object store only in a versionchange transaction
您只能在 versionchange 事务中创建或删除对象存储
see: https://developer.mozilla.org/en-US/docs/IndexedDB/IDBDatabase
请参阅：https: //developer.mozilla.org/en-US/docs/IndexedDB/IDBDatabase
回答by Wladimir Palant
I didn't try that code but judging by the documentationyou shouldn't pass an empty list as first parameter to db.transaction()- it should rather be db.transaction(["customers"], ...)because you want to work with that object store.
我没有尝试该代码，但根据文档判断，您不应该将空列表作为第一个参数传递给db.transaction()- 应该是db.transaction(["customers"], ...)因为您想使用该对象存储。
