Indexeddb-通过索引键更新记录

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问题描述

我有一个对象存储区，其键路径为"id"(自动递增)，并且在该存储区上具有从服务器生成的键路径为"myId"的唯一索引.当我需要更新记录时，我将没有可用的"id"，因此考虑到索引是唯一的，如何仅通过使用"myId"来更新记录?

I have an object store with keypath "id" (autoincrement), and a unique index on that store with keypath "myId" that is generated from a server.When I need to update a record, I won't have "id" available, so how can I update the record just by using "myId" considering that the index is unique?

我已经尝试使用mystore.put(record)，但是由于存在具有"myId"的记录，因此出现了错误.

I already tried using mystore.put(record), but that gives an error since a record with "myId" already exists.

推荐答案

由于您在myId属性上已经具有唯一的键索引，因此可以基于该值检索记录.您需要使用 only IDBKeyRange和cursor查询，如下所示:

Since you've already got a unique key index on your myId property you can retrieve the record based on that value. You'll need to use the only IDBKeyRange and a cursor query, like so:

var transaction = db.transaction('myStore');
var store = transaction.objectStore('myStore');
var index = store.index('myId_Index');
var keyRange = IDBKeyRange.only(obj.myId);

var request = index.openCursor(keyRange);

request.onsucess = function (e) {
    var cursor = e.target.result;

    if (cursor) {
        var item = cursor.value;
        obj.id = item.id;
        //save the object
    }
};

此外，如果要使用同一事务进行更新，则需要像我一样将其设置为readwrite而不是readonly.

Also, if you want to update using the same transaction you'll need to make it a readwrite not readonly as I did.

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