IDBObjectStore.add() - Web APIs 编辑

The add() method of the IDBObjectStore interface 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.

To determine if the add operation has completed successfully, listen for the transaction’s complete event in addition to the IDBObjectStore.add request’s success event, because the transaction may still fail after the success event fires. In other words, the success event is only triggered when the transaction has been successfully queued.

The add method is an insert only method. If a record already exists in the object store with the key parameter as its key, then an error ConstrainError event is fired on the returned request object. For updating existing records, you should use the IDBObjectStore.put method instead.

Note:

Syntax

var request = objectStore.add(value);
var request = objectStore.add(value, key);

Parameters

value

The value to be stored.

key Optional

The key to use to identify the record. If unspecified, it results to null.

Returns

An IDBRequest object on which subsequent events related to this operation are fired.

Exceptions

This method may raise a DOMException of one of the following types:

Example

In the following code snippet, we open a read/write transaction on our database and add some data to an object store using add(). Note also the functions attached to transaction event handlers to report on the outcome of the transaction opening in the event of success or failure. 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 the db variable.
  // This is used a lot below
  db = DBOpenRequest.result;

  // Run the addData() function to add the data to the database
  addData();
};

function addData() {
  // Create a new object ready to insert into the IDB
  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) {
    // report the success of our request
    note.innerHTML += '<li>Request successful.</li>';
  };
};

Specification

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.)