This API is available on Firefox OS for internal applications only.
The DataStoreCursor
interface of the Data Store API represents a cursor that allows apps to iterate through a list of DataStoreTask
objects representing the change history of the data store, for use when synchronizing the data.
Note: The Data Store API is available in Web Workers, from Firefox 32 onwards (Firefox OS 2.0; see bug 949325.)
Properties
DataStoreCursor.store
Read only- Returns the name of the store that the cursor is iterating over.
Methods
DataStoreCursor.next()
- Makes a request to retrieve information about the next operation that changes a record in the data store. Returns a
Promise
of typeDataStoreTask
. DataStoreCursor.close()
- Makes a request to terminate the cursor.
Example
In the following example, we use navigator.getDataStores
to return a list of DataStore
objects representing data stores on the device called contacts
. Since there is only one such data store, we can access it inside the outer promise using stores[0]
. The next promise uses DataStore.getLength
to return the number of records in the store. If the value is 0, we populate the data store with records contained in the contactsInit
object; if there is already data in the store, we run DataStore.sync
to create a DataStoreCursor
object allowing us to loop through any additions since the code last accessed the data store and update the data display as necessary.
The cursor is passed to the runNextTask()
function, which calls DataStoreCursor.next
to start the process of managing the next task — the resulting DataStoreTask
object is passed to the manageTask()
function to work out what to do with it. runNextTask()
is then called repeatedly by manageTask()
until the cursor has finished working through all the records.
navigator.getDataStores('contacts').then(function(stores) { stores[0].getLength().then(function(storeLength) { if(storeLength == 0) { for(i = 0; i < contactsInit.length; i++) { addContact(stores[0],contactsInit[i]); }; } else { var cursor = stores[0].sync(); runNextTask(cursor); } }); }); function runNextTask(cursor) { cursor.next().then(function(task) { manageTask(cursor, task); }); } function manageTask(cursor, task) { if (task.operation == 'done') { // Finished adding contacts! return; } if (task.operation == 'add') { // Add the contacts that are different to how it was before displayExisting(task.id, task.data); } runNextTask(cursor); }
Note: This code is taken from our Data Store Contacts Editor demo. Look through the code to help you understand better what is going on, and how the full code works.
Specifications
Specification | Status | Comment |
---|---|---|
Data Store API The definition of 'DataStoreCursor' 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
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | No support | No support | No support | No support | No support |
Feature | Android | Chrome | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | No support | No support | No support | 1.0.1 | No support | No support | No support |
Available in web workers | No support | No support | No support | 2.0 | No support | No support | No support |