Android WebView database storage returns null

Question

Here is my problem. I am trying to store data from my web app locally in an HTML5 database. Thing is, the database I try to open with my javascript returns null.

Here is the Android code:

public class NotepadActivity extends Activity {
WebView main_view = null;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //Get rid of the android title bar
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.main);

        main_view = (WebView) findViewById(R.id.main_webview);
        WebSettings settings = main_view.getSettings();

        settings.setJavaScriptEnabled(true);
        settings.setDatabasePath("/data/data/"+this.getPackageName()+"/databases/");
        settings.setDomStorageEnabled(true);

        main_view.loadUrl("file:///android_asset/index.html");

        main_view.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                return false;
            }
            @Override
            public void onReceivedError(WebView view, int errorCod,String description,    String failingUrl) {
                Toast.makeText(NotepadActivity.this, "Error: " + description , Toast.LENGTH_LONG).show();
            }   
        });

        main_view.setWebChromeClient(new WebChromeClient() {
               public void onConsoleMessage(String message, int lineNumber, String sourceID) {
                 Log.d("Notepad", message + " -- From line "
                                 + lineNumber + " of "
                                 + sourceID);
              }
        });
     }

     public void onExceededDatabaseQuota(String url, String
            databaseIdentifier, long currentQuota, long estimatedSize, long
            totalUsedQuota, WebStorage.QuotaUpdater quotaUpdater) {
                        quotaUpdater.updateQuota(estimatedSize * 2);
            } 
}

And the relevant JavaScript:

     /* DB and result values */
    DB_name: "NotepadDB",
    DB_version: "1",
    DB_displayName: "Notepad Database",
    DB_sizeEstimate: 5 * 1024 * 1024,
    DB: null,

 ....



    /* Open a connection to the DB (or create if it doesn't exist) */
    openConnection: function() {
        App.log("App > DB > openConnection > Attempting to access database");
        App.val.DB = window.openDatabase(App.val.DB_name, App.val.DB_version, 
                        App.val.DB_displayName, App.val.DB_sizeEstimate, App.DB.initializeDatabase);
    },

    /* Only called when the database is initially created */
    initializeDatabase: function(database) {
        App.val.DB = database;

        //Create the required table
        App.val.DB.transaction(
            function (tx) {tx.executeSql('CREATE TABLE ' + App.schema.tableName + ' (' + App.schema.ID+ ' int unique, ' + App.schema.title + ' text, ' + App.schema.content + ' text, ' + App.schema.date + ' datetime)',
                [],
                function (tx, res) {
                    App.log("App > DB > intializeDatabase > Table Created Successfully");
                    App.DB.loadAllNotes();
                },
                function (tx, err) {
                    App.log("App > DB > intializeDatabase > ERROR - Table creation failed - code: " + err.code + ", message: " + err.message);
                    App.error("Unable to create database. Please try again later.");
                });
            }
        );
    },

    loadAllNotes: function() {
        if(App.val.DB != null) {
            //Do some stuff
        } else {
            App.log("App > DB > loadAllNotes > Database was NULL");
        }
    }

In my LogCat log I am seeing App.log("App > DB > loadAllNotes > Database was NULL"); is executing.

Is there something I am missing here? Why is the database null?

score 2 · Accepted Answer · answered Jun 21 '12 at 00:39

2

Solved it. The problem was I overlooked the following code:

     public void onExceededDatabaseQuota(String url, String
        databaseIdentifier, long currentQuota, long estimatedSize, long
        totalUsedQuota, WebStorage.QuotaUpdater quotaUpdater) {
                    quotaUpdater.updateQuota(estimatedSize * 2);
        }

This function should be within the main_view.setWebChromeClient(new WebChromeClient() { function, as it needs to override. D'oh!

answered Jun 21 '12 at 00:39

kz3

785
2
10
23

Wow! I didn't even know that I had to set `onExceededDatabaseQuota` for WebSQL to work. This has saved me a lot of time, thanks. – Maarten Sep 04 '13 at 07:53

score 0 · Answer 2 · edited May 23 '17 at 12:12

0

It would be easier to create a SQlite database file and put it into your Assets directory and load the file onto the SDcard when the app is first ran. U can use a FireFox addon for the db editor. This will require a lot less code in your app. You can use my methods I posted here on SO. Just use the .sql file instead of a txt file - This is what I do with my apps .

edited May 23 '17 at 12:12

Community

1
1

answered Jun 20 '12 at 22:57

I'll take this into consideration, but this app is being ported over from another platform so I'd rather keep the code more or less the same. Makes it easier to update both apps, rather than have to write separate code for each. – kz3 Jun 20 '12 at 23:48

Android WebView database storage returns null

2 Answers2