Phonegap本地存储返回空结果

Question

On app's first load, I retrieve data from storage (Phonegap's WebSQL storage type). Phonegap storage results load fine. Until...

When I go to another page in the app: <a href="page2.html" rel="external">Link</a>

If I return back to that main page from the second page using window.location.href in Javascript, I retrieve the WebSQL data again (same function as before).

Phonegap Storage calls the success function (no error), but with an empty result set . It seems to be loading from a second database where I haven't stored anything into (see edit below).

If I force quit app and reopen, storage loads fine again, which shows me that the results in the DB are NOT being deleted.

I load the storage after ondeviceready is fired. What could be wrong?

Note:
1. This is not happening on simulators. only happening on real Android 4.0 device.
2. This app uses jQuery / jQuery Mobile.

function ondeviceready() {
   db = window.openDatabase("test", "1.0", "test DB", 2000000);
   // . . . //
   db.transaction(function(tx) {
      tx.executeSql('SELECT * FROM table ORDER BY name', [], querysuccess, function(tx, e) {
         errorAlert();
      });
   }), errorCB;
}

EDIT : I'm noticing now that if I add a new row when app is first loaded, it stores in one database. Then, if I go to the second page and then back to the first page, and I add another row, it also stores, but in a separate database! (so that's what it seems to be doing). So strange, I see this happening. All my rows are saved and persistent, but the query returns a different group of results depending on whether I went to the second page or not...

Also: The second page is having a jQuery error for some reason. I just created a blank page with a script link to jQuery, and there is an error. Strange... I wonder if this error is affecting the database? I'm trying to discover how to solve this error.

Answer 1

I've encountered an issue similar to this one before, but my problem was that I was trying to write to the same database from the Java side and the Javascript side. This is how I was able to solve it:

• First I ran the app on an Android Simulator and used DDMS to access the databases and that is when I realised that the two were writing in different databases.

• I changed from using WebSQL , to using proper SQLite database, and I started getting consistent results after that. It's a drop-in replacement for the phonegap's implementation of database storage, so no need to change your code much. Please see https://github.com/brodyspark/PhoneGap-SQLitePlugin-Android .

I think it's also important to note that WebSQL has some storage limitations, so you might be better off using SQLite that WebSQL . Please see: http://www.steveworkman.com/html5-2/standards/2011/the-limitations-of-websql-and-offline-apps/

Hope this helps :-)

Answer 2

What I've done is I now load the external HTML page through Ajax:

$.mobile.changePage("page2.html");

I also switched to pgsqlite as recommended.