IDBDatabase
The IDBDatabase
interface of the IndexedDB API provides a connection to a database (en-US); you can use an IDBDatabase
object to open a transaction (en-US) 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.
Nota: Esta característica está disponible en Web Workers
Nota: Everything you do in IndexedDB always happens in the context of a transaction (en-US), 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.
Methods
Inherits from: EventTarget (en-US)
IDBDatabase.close()
(en-US)-
Returns immediately and closes the connection to a database in a separate thread.
IDBDatabase.createObjectStore()
(en-US)-
Creates and returns a new object store or index.
IDBDatabase.deleteObjectStore()
(en-US)-
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
(en-US)) containing theIDBTransaction.objectStore
(en-US) method, which you can use to access your object store. Runs in a separate thread.
Properties
IDBDatabase.name
(en-US) Read only-
A
DOMString
that contains the name of the connected database. IDBDatabase.version
(en-US) Read only-
A 64-bit integer (en-US) that contains the version of the connected database. When a database is first created, this attribute is an empty string.
IDBDatabase.objectStoreNames
(en-US) Read only-
A
DOMStringList
(en-US) that contains a list of the names of the object stores (en-US) currently in the connected database.
Event handlers
IDBDatabase.onabort
(en-US)-
Fires when access of the database is aborted.
IDBDatabase.onclose
(en-US)-
Fires when the
close
event occurs; this happens when the database is unexpectedly closed, such as during application shutdown. IDBDatabase.onerror
(en-US)-
Fires when access to the database fails.
IDBDatabase.onversionchange
(en-US)-
Fires when a database structure change (
IDBOpenDBRequest.onupgradeneeded
(en-US) event orIDBFactory.deleteDatabase()
(en-US) was requested elsewhere (most probably in another window/tab on the same computer). This is different from the version change transaction (seeIDBVersionChangeEvent
(en-US)), but it is related.
Example
In the following code snippet, we open a database asynchronously (IDBFactory
(en-US)), 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').objectStore('toDoList');
Especificaciones
Specification |
---|
Indexed Database API 3.0 # database-interface |
Compatibilidad con navegadores
BCD tables only load in the browser
See also
- Using IndexedDB
- Starting transactions:
IDBDatabase
- Using transactions:
IDBTransaction
(en-US) - Setting a range of keys:
IDBKeyRange
(en-US) - Retrieving and making changes to your data:
IDBObjectStore
- Using cursors:
IDBCursor
- Reference example: To-do Notifications (view example live.)