B2G OS

DataStoreChangeEvent.id

This API is available on Firefox OS for internal applications only.

The id read-only property of the DataStoreChangeEvent interface returns the identifier of the changed record in the data store. This must return null if the operation is cleared.

Note: The Data Store API is available in Web Workers, from Firefox 32 onwards (Firefox OS 2.0; see bug 949325.)

Syntax

myId = e.id;

Value

A DataStoreKey.

Example

In the following snippet we retrieve all the data stores on the device with the name "contacts", then we use DataStore.sync to create a cursor to use for syncing the app with the current "content" data store (displaying new items, etc.) This cursor is passed to the runNextTask() function that will deal with running through the updates in some way. Next, we include some code inside an onchange function so that when a change is made we return the DataStoreChangeEvent (e in this case), find out what type of task the change was, and then take action based on this type (either adding or deleting a contact's information.)

The deleteContact() and loadContact() functions are passed e.id to use in their functionality.

navigator.getDataStores('contacts').then(function(stores) {
  var cursor = stores[0].sync();
  runNextTask(cursor);

  stores[0].onchange = function(e) {
    if (e.operation == 'removed') {
      // Delete the contact
      deleteContact(e.id);
    }

    if (e.operation == 'added') {
      stores[0].get(e.id).then(function(obj) {
        // Add the new contact
        loadData(obj,e.id);
      });
    }
  }
});

Note: To see this code used in the context of a complete app, check out our The Data Store Contacts Viewer example changeevent version on GitHub.

Specifications

Specification Status Comment
Data Store API
The definition of 'id' in that specification.
Draft  

The discussion concerning this API's creation happened in various Mozilla mailing lists and other places. A summary of the discussion and further pointers can be found on the Mozilla Wiki. For further feedback and questions, send mail to the dev-webapi mailing list.

Browser compatibility

Supported in Firefox OS 1.0.1.
Available in web workers in Firefox OS 2.0.

See also

Document Tags and Contributors

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