mozilla
Your Search Results

    IDBIndex.openKeyCursor()

    This article is in need of a technical review.

    The openKeyCursor() method of the IDBIndex interface returns an IDBRequest object, and, in a separate thread, creates a cursor over the specified key range, as arranged by this index.

    The method sets the position of the cursor to the appropriate key, based on the specified direction.

    • If the key range is not specified or is null, then the range includes all the keys.
    • If at least one key matches the key range, then a success event is fired on the result object, with its result set to the new IDBCursor object; the value of the cursor object is set to the value of the found record.
    • If no keys ranges match the key range specified, then then an error event is fired on the request object.

    Syntax

    var myIndex = objectStore.index('index');
    var request = myIndex.openKeyCursor();

    Returns

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

    Exceptions

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

    Exception Description
    TransactionInactiveError This IDBIndex's transaction is inactive.
    TypeError The value for the direction parameter is invalid.
    DataError

    The key or key range provided contains an invalid key.

    InvalidStateError The IDBIndex has been deleted or removed.

    Example

    Important: This example does not yet work. Research is currently being done on this method, and more useful information will be available soon.

    In the following example we open a transaction and an object store, then get the index lName from a simple contacts database. We then open a key cursor on the index using openKeyCursor() — this works the same as opening a cursor directly on an ObjectStore using IDBObjectStore.openCursor except that the returned records are sorted based on the index, not the primary key.

    Finally, we iterate through each record, and insert the data into an HTML table. For a complete working example, see our IDBIndex-example demo repo (View the example live.)

    function displayDataByIndex() {
      tableEntry.innerHTML = '';
      var transaction = db.transaction(['contactsList'], 'readonly');
      var objectStore = transaction.objectStore('contactsList');
    
      var myIndex = objectStore.index('lName'); 
    
      myIndex.openKeyCursor().onsuccess = function(event) {
        var cursor = event.target.result;
        if(cursor) {
          var tableRow = document.createElement('tr');
          tableRow.innerHTML =   '<td>' + cursor.value.id + '</td>'
                               + '<td>' + cursor.value.lName + '</td>'
                               + '<td>' + cursor.value.fName + '</td>'
                               + '<td>' + cursor.value.jTitle + '</td>'
                               + '<td>' + cursor.value.company + '</td>'
                               + '<td>' + cursor.value.eMail + '</td>'
                               + '<td>' + cursor.value.phone + '</td>'
                               + '<td>' + cursor.value.age + '</td>';
          tableEntry.appendChild(tableRow);  
    
          cursor.continue();
        } else {
          console.log('Entries all displayed.');    
        }
      };
    };
     

    Parameters

    range
    Optional. The key range to use as the cursor's range.
    direction
    Optional. The cursor's required direction. See IDBCursor Constants for possible values.

    Specification

    Specification Status Comment
    Indexed Database API
    The definition of 'openKeyCursor()' in that specification.
    Candidate Recommendation  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
    Basic support 23webkit
    24
    10 moz
    16.0 (16.0)
    10, partial 15 7.1
    count() 23 22.0 (22.0) 10, partial 15 7.1
    getAll() and getAllKeys() Not supported 24.0 (24.0)
    behind dom.indexedDB.experimental  pref
    Not supported Not supported Not supported
    Feature Android Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
    Basic support 4.4 22.0 (22.0) 1.0.1 10 22 Not supported
    count() 4.4 22.0 (22.0) 1.0.1 10 22 Not supported
    getAll() and getAllKeys() Not supported 24.0 (24.0)
    behind dom.indexedDB.experimental  pref
    1.1 behind
    dom.indexedDB.experimental  pref
    Not supported Not supported Not supported

    Be careful in Chrome as it still implements the old specification along the new one. Similarly it still has the prefixed webkitIndexedDB property even if the unprefixed indexedDB is present.

    See also

     

     

    Document Tags and Contributors

    Contributors to this page: fscholz, chrisdavidmills
    Last updated by: fscholz,