Android SQLite DB notifications

Question

I am writing an Android app that needs to be notified whenever a given SQLite database changes (any new row added, deleted or updated).

Is there any programmatic way to listen to these notifications ?

Is writing DB triggers for each table the only way ?

SQLLite database operations are those from your app only (or) could be from anywhere? — kosa
– kosa, Commented Jan 9, 2012 at 5:17

NuSkooler · Accepted Answer · 2012-03-05 17:51:42Z

5

SQLite provides Data Change Notification Callbacks. I don't think that Android exposes them directly but it does have for example CursorAdapter which provides some change notifications.

As thinksteep asked however, do you expect your DB to be changed outside the scope of your own application?

answered Mar 5, 2012 at 17:51

NuSkooler

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3 Comments

Mohammed Subhi Sheikh Quroush Over a year ago

As thinksteep asked however, do you expect your DB to be changed outside the scope of your own application? very helpful notice

AlikElzin-kilaka Over a year ago

What change notifications does CursorAdapter provide?

Mooing Duck Over a year ago

CursorAdapter's notifications are based on Android stuff that is unrelated to database changes directly. It is up to the programmer to notify that mechanism when the database changes.

Moog · Accepted Answer · 2012-03-05 18:01:16Z

1

You can register an observer class such as DataSetObserver

Then whenever you change something you can call cursor.registerDataSetObserver(..) to register observe changes.

It's not well documented but I'm sure that there are some examples out there

answered Mar 5, 2012 at 18:01

Moog

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2 Comments

AlikElzin-kilaka Over a year ago

From what I understand, the cursor provides a snapshot of the data. This means that unless you re-query the data, the listener won't be invoked. From the documentation: "Register an observer that is called when changes happen to the contents of the this cursors data set, for example, when the data set is changed via requery(), deactivate(), or close()."

Mooing Duck Over a year ago

This triggers when the programmer calls content provider.notifyChange, and doesn't auto detect changes.

satur9nine · Accepted Answer · 2012-07-26 03:44:44Z

You can use also use the getContentResolver().registerContentObserver but unfortunately it doesn't tell you what kind of change was made, it could be a delete, insert or update.

If you control the ContentProvider that interfaces with the DB then you could fire an Intent or use getContentResolver().notifyChange to send a special Uri notification that identifies both the table and action. An example Uri you could notify with might be: content://my-authority/change/table-name/insert

But even then you don't know exactly which rows were effected by the change.

Seems like triggers that write to a change log table will guarantee you hear about all changes regardless of where they came from, and you can know the exact id and action that occurred. Unfortunately it means slower inserts/updates/deletes and it means you probably need a Service of some kind to process and delete changes.

I'd love to hear if these is some better solution out there!

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