我的想法是从服务器下载一个大文件。
存储在 IndexedDB 中的 block 。
下载所有 block 后，将所有记录合并为一个(如 SQL SELECT * FROM XXX ...)。
- 保存到磁盘“saveAs()”或创建指向 IndexedDB 的 URL...
(或任何想法？)
我不知道如何进行第 2 步和第 3 步
(下面是在数据库中存储 10,000 条记录的示例，步骤 2 之后的预期输出应该是 SusanSusanSusanSusanSusan...)
if (transaction) {
transaction.oncomplete = function () {
}
transaction.onabort = function () {
writeToConsoleScreen("transaction aborted.");
localDatabase.db.close();
}
transaction.ontimeout = function () {
writeToConsoleScreen("transaction timeout.");
localDatabase.db.close();
}
var store = transaction.objectStore(osTableName);
if (store) {
var req;
var customer = {};
// create ten thousand records
for (var loop = 0; loop < 10000; loop++) {
customer = {};
customer.fname = 'Susan';
req = store.add(customer);
req.onsuccess = function (ev) {
}
req.onerror = function (ev) {
writeToConsoleScreen("Failed to add record." + " Error: " + ev.message);
}
}
}
}
最佳答案
<!DOCTYPE html>
<script>
var open = indexedDB.open('chunks-example');
open.onupgradeneeded = function() {
// Create schema if necessary
var db = open.result;
db.createObjectStore('chunks');
};
// 1. Chunks stored into an IndexedDB.
open.onsuccess = function() {
var db = open.result;
var tx = db.transaction('chunks', 'readwrite');
var store = tx.objectStore('chunks');
for (var i = 0; i < 10; ++i) {
// For realz, this would be via
// XMLHttpRequest.response and async.
var chunk = new Blob(['chunk ' + i + '\n'],
{type: 'application/octet-stream'});
store.put(chunk, i);
}
tx.oncomplete = function() { merge(db); };
};
// 2. After "download" all chunks, merge all records into one
function merge(db) {
var tx = db.transaction('chunks');
var store = tx.objectStore('chunks');
var chunks = [];
var request = store.openCursor();
request.onsuccess = function() {
var cursor = request.result;
if (cursor) {
chunks.push(cursor.value);
cursor.continue();
} else {
saveAs('myfile', new Blob(chunks,
{type: 'application/octet-stream'}));
}
};
}
// 3. Save into disk "saveAs()"
function saveAs(filename, blob) {
var a = document.documentElement.appendChild(document.createElement('a'));
a.href = URL.createObjectURL(blob);
a.download = filename;
a.click();
a.parentElement.remove(a);
}
</script>
关于javascript - HTML5 IndexedDB - 如何将所有记录合并为一个，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24765957/