IDBDatabase - Web APIs 编辑

The IDBDatabase interface of the IndexedDB API provides a connection to a database; you can use an IDBDatabase object to open a transaction on your database then create, manipulate, and delete objects (data) in that database. The interface provides the only way to get and manage versions of the database.

Note:

Note: Everything you do in IndexedDB always happens in the context of a transaction, representing interactions with data in the database. All objects in IndexedDB — including object stores, indexes, and cursors — are tied to a particular transaction. Thus, you cannot execute commands, access data, or open anything outside of a transaction.

  <div id="interfaceDiagram" style="display: inline-block; position: relative; width: 100%; padding-bottom: 11.666666666666666%; vertical-align: middle; overflow: hidden;"><svg style="display: inline-block; position: absolute; top: 0; left: 0;" viewbox="-50 0 600 70" preserveAspectRatio="xMinYMin meet"><a xlink:href="/wiki/en-US/docs/Web/API/EventTarget" target="_top"><rect x="1" y="1" width="110" height="50" fill="#fff" stroke="#D4DDE4" stroke-width="2px" /><text  x="56" y="30" font-size="12px" font-family="Consolas,Monaco,Andale Mono,monospace" fill="#4D4E53" text-anchor="middle" alignment-baseline="middle">EventTarget</text></a><polyline points="111,25  121,20  121,30  111,25" stroke="#D4DDE4" fill="none"/><line x1="121" y1="25" x2="151" y2="25" stroke="#D4DDE4"/><a xlink:href="https://developer.mozilla.org/wiki/en-US/docs/Web/API/IDBDatabase" target="_top"><rect x="151" y="1" width="110" height="50" fill="#F4F7F8" stroke="#D4DDE4" stroke-width="2px" /><text  x="206" y="30" font-size="12px" font-family="Consolas,Monaco,Andale Mono,monospace" fill="#4D4E53" text-anchor="middle" alignment-baseline="middle">IDBDatabase</text></a></svg></div>

  a:hover text { fill: #0095DD; pointer-events: all;}

Properties

IDBDatabase.name Read only

A DOMString that contains the name of the connected database.

IDBDatabase.version Read only

A 64-bit integer that contains the version of the connected database. When a database is first created, this attribute is an empty string.

IDBDatabase.objectStoreNames Read only

A DOMStringList that contains a list of the names of the object stores currently in the connected database.

Methods

Inherits from: EventTarget

IDBDatabase.close()

Returns immediately and closes the connection to a database in a separate thread.

IDBDatabase.createMutableFile()

Creates a file handle, allowing files to be stored inside an IndexedDB database.

IDBDatabase.createObjectStore()

Creates and returns a new object store or index.

IDBDatabase.deleteObjectStore()

Destroys the object store with the given name in the connected database, along with any indexes that reference it.

IDBDatabase.transaction()

Immediately returns a transaction object (IDBTransaction) containing the IDBTransaction.objectStore method, which you can use to access your object store. Runs in a separate thread.

Events

Listen to these events using addEventListener() or by assigning an event listener to the oneventname property of this interface.

abort

Fired when a transaction is aborted and bubbles up to the connection object. Also available via the onabort property.

close

Fired when the database connection is unexpectedly closed. Also available via the onclose property.

error

Fired when a request returns an error and the event bubbles up to the connection object. Also available via the onerror property.

versionchange

Fired when a database structure change was requested. Also available via the onversionchange property.

Example

In the following code snippet, we open a database asynchronously (IDBFactory), handle success and error cases, and create a new object store in the case that an upgrade is needed (IDBdatabase). For a complete working example, see our To-do Notifications app (view example live.)

// Let us open our database
var DBOpenRequest = window.indexedDB.open("toDoList", 4);

// these two event handlers act on the IDBDatabase object,
// when the database is opened successfully, or not
DBOpenRequest.onerror = function(event) {
  note.innerHTML += '<li>Error loading database.</li>';
};

DBOpenRequest.onsuccess = function(event) {
  note.innerHTML += '<li>Database initialised.</li>';

  // store the result of opening the database in the db
  // variable. This is used a lot later on
  db = DBOpenRequest.result;

  // Run the displayData() function to populate the task
  // list with all the to-do list data already in the IDB
  displayData();
};

// This event handles the event whereby a new version of
// the database needs to be created Either one has not
// been created before, or a new version number has been
// submitted via the window.indexedDB.open line above

DBOpenRequest.onupgradeneeded = function(event) {
  var db = event.target.result;

  db.onerror = function(event) {
    note.innerHTML += '<li>Error loading database.</li>';
  };

  // Create an objectStore for this database using
  // IDBDatabase.createObjectStore

  var objectStore = db.createObjectStore("toDoList", { keyPath: "taskTitle" });

  // define what data items the objectStore will contain

  objectStore.createIndex("hours", "hours", { unique: false });
  objectStore.createIndex("minutes", "minutes", { unique: false });
  objectStore.createIndex("day", "day", { unique: false });
  objectStore.createIndex("month", "month", { unique: false });
  objectStore.createIndex("year", "year", { unique: false });

  objectStore.createIndex("notified", "notified", { unique: false });

  note.innerHTML += '<li>Object store created.</li>';
};

This next line opens up a transaction on the Database, then opens an object store that we can then manipulate the data inside of.

var objectStore = db.transaction('toDoList', 'readwrite').objectStore('toDoList');

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Using IndexedDB
• Starting transactions: IDBDatabase
• Using transactions: IDBTransaction
• Setting a range of keys: IDBKeyRange
• Retrieving and making changes to your data: IDBObjectStore
• Using cursors: IDBCursor
• Reference example: To-do Notifications (view example live.)