IDBObjectStore - Web APIs 编辑

The IDBObjectStore interface of the IndexedDB API represents an object store in a database. Records within an object store are sorted according to their keys. This sorting enables fast insertion, look-up, and ordered retrieval.

Note:

Properties

IDBObjectStore.indexNames Read only

A list of the names of indexes on objects in this object store.

IDBObjectStore.keyPath Read only

The key path of this object store. If this attribute is null, the application must provide a key for each modification operation.

IDBObjectStore.name

The name of this object store.

IDBObjectStore.transaction Read only

The IDBTransaction object to which this object store belongs.

IDBObjectStore.autoIncrement Read only

The value of the auto increment flag for this object store.

Methods

IDBObjectStore.add()

Returns an IDBRequest object, and, in a separate thread, creates a structured clone of the value, and stores the cloned value in the object store. This is for adding new records to an object store.

IDBObjectStore.clear()

Creates and immediately returns an IDBRequest object, and clears this object store in a separate thread. This is for deleting all current records out of an object store.

IDBObjectStore.count()

Returns an IDBRequest object, and, in a separate thread, returns the total number of records that match the provided key or IDBKeyRange. If no arguments are provided, it returns the total number of records in the store.

IDBObjectStore.createIndex()

Creates a new index during a version upgrade, returning a new IDBIndex object in the connected database.

IDBObjectStore.delete()

returns an IDBRequest object, and, in a separate thread, deletes the store object selected by the specified key. This is for deleting individual records out of an object store.

IDBObjectStore.deleteIndex()

Destroys the specified index in the connected database, used during a version upgrade.

IDBObjectStore.get()

Returns an IDBRequest object, and, in a separate thread, returns the store object store selected by the specified key. This is for retrieving specific records from an object store.

IDBObjectStore.getKey()

Returns an IDBRequest object, and, in a separate thread retrieves and returns the record key for the object in the object stored matching the specified parameter.

IDBObjectStore.getAll()

Returns an IDBRequest object retrieves all objects in the object store matching the specified parameter or all objects in the store if no parameters are given.

IDBObjectStore.getAllKeys()

Returns an IDBRequest object retrieves record keys for all objects in the object store matching the specified parameter or all objects in the store if no parameters are given.

IDBObjectStore.index()

Opens an index from this object store after which it can, for example, be used to return a sequence of records sorted by that index using a cursor.

IDBObjectStore.openCursor()

Returns an IDBRequest object, and, in a separate thread, returns a new IDBCursorWithValue object. Used for iterating through an object store by primary key with a cursor.

IDBObjectStore.openKeyCursor() 

Returns an IDBRequest object, and, in a separate thread, returns a new IDBCursor. Used for iterating through an object store with a key.

IDBObjectStore.put()

Returns an IDBRequest object, and, in a separate thread, creates a structured clone of the value, and stores the cloned value in the object store. This is for updating existing records in an object store when the transaction's mode is readwrite.

Example

This example shows a variety of different uses of object stores, from updating the data structure with IDBObjectStore.createIndex inside an onupgradeneeded function, to adding a new item to our object store with IDBObjectStore.add. For a full working example, see our To-do Notifications app (view example live.)

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

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

  // store the result of opening the database in db.
  db = DBOpenRequest.result;
};

// 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

  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>';
};

// Create a new item to add in to the object store
var newItem = [
  { taskTitle: "Walk dog", hours: 19, minutes: 30, day: 24, month: 'December', year: 2013, notified: "no" }
];

// open a read/write db transaction, ready for adding the data
var transaction = db.transaction(["toDoList"], "readwrite");

// report on the success of the transaction completing, when everything is done
transaction.oncomplete = function(event) {
  note.innerHTML += '<li>Transaction completed.</li>';
};

transaction.onerror = function(event) {
  note.innerHTML += '<li>Transaction not opened due to error. Duplicate items not allowed.</li>';
};

// create an object store on the transaction
var objectStore = transaction.objectStore("toDoList");
// make a request to add our newItem object to the object store
var objectStoreRequest = objectStore.add(newItem[0]);

objectStoreRequest.onsuccess = function(event) {
  note.innerHTML += '<li>Request successful .</li>';
}

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.)