This API is available on Firefox OS for internal applications 仅。
operation
只读特性在
DataStoreChangeEvent
interface returns the type of operation that represents the current change that has been made to the data store.
注意 : The Data Store API is available in Web 工作者 , from Firefox 32 onwards (Firefox OS 2.0; see bug 949325 )。
myOperation = e.operation;
A
DataStoreOperation
(见
Operation types
).
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 operation the change is, and then take action based on this type (either adding or deleting a contact's information.)
e.operation
is used to check what type of operation the current change is.
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);
});
}
}
});
注意 : 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.
The different operation types used in
DataStoreChangeEvent
are (see also the
spec definitions
):
| Enumeration | 描述 |
|---|---|
添加
|
The record is added into the data store. |
updated
|
The record is updated in the data store. |
removed
|
The record is deleted from the data store. |
cleared
|
All records are deleted from the data store. |
注意
: These are currently different to the operation types returned by
DataStoreTask
. This discrepancy will be fixed soon at an appropriate time.
| 规范 | 状态 | 注释 |
|---|---|---|
|
Data Store API
The definition of 'operation' in that specification. |
草案 |
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.