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From "Wayne Fisher (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CB-482) window.openDatabase on Android doesn't handle the version parameter very well.
Date Thu, 12 Apr 2012 01:46:16 GMT
window.openDatabase on Android doesn't handle the version parameter very well.
------------------------------------------------------------------------------

                 Key: CB-482
                 URL: https://issues.apache.org/jira/browse/CB-482
             Project: Apache Callback
          Issue Type: Bug
          Components: Android
    Affects Versions: 1.4.0, 1.3.0, 1.2.0
            Reporter: Wayne Fisher
            Assignee: Joe Bowser


In the database code for Android, near the very bottom of the phonegap.js file, we find the
following code:

{code}
    if (typeof window.openDatabase === "undefined") {
        setupDroidDB();
    } else {
        window.openDatabase_orig = window.openDatabase;
        window.openDatabase = function(name, version, desc, size){
            // Some versions of Android will throw a SECURITY_ERR so we need 
            // to catch the exception and seutp our own DB handling.
            var db = null;
            try {
                db = window.openDatabase_orig(name, version, desc, size);
            } 
            catch (ex) {
                db = null;
            }

            if (db == null) {
                setupDroidDB();
                return DroidDB_openDatabase(name, version, desc, size);
            }
            else {
                return db;
            }
        };
    }
{code}

The comment makes reference to a SECURITY_ERR exception that appears to occur on some versions
of Android. The following try/catch block will catch the SECURITY_ERR exception and proceed
to setup the DroidDB.

However, the try/catch block does not take into account that other exceptions can occur. In
particular, from w3.org the following specifies an exception that should be raised if the
specified version does not match the actual database version:

{quote}
If the database version provided is not the empty string, and the database already exists
but has a different version, or no version, then the method must raise an INVALID_STATE_ERR
exception.
{quote}

It would appear to me that the above code should be modified to be more selective about the
handling of exceptions. If an INVALID_STATE_ERR exception is raised, it should not setup the
DroidDB but instead allow it to propagate to the caller.

I came across this issue when attempting to update a database to a new version due to a requirement
for additional columns. My code attempted to open the new database version and if it failed
(due to exception) it would fallback and attempt to open and upgrade the previous version.
What happened was that it was never able to find the previous version since the INVALID_STATE_ERR
exception was being thrown which was caught by the PhoneGap code which would then proceed
to setup the DroidDB. There was no way to get to the original database.

The above code appears the same in PhoneGap v1.2, 1.3, and 1.4. I didn't check 1.5. In 1.5
the code moved to be much earlier in the file and changed slightly but is effectively the
same:

{code}
        // First patch WebSQL if necessary
        if (typeof window.openDatabase == 'undefined') {
            // Not defined, create an openDatabase function for all to use!
            window.openDatabase = storage.openDatabase;
        } else {
            // Defined, but some Android devices will throw a SECURITY_ERR -
            // so we wrap the whole thing in a try-catch and shim in our own
            // if the device has Android bug 16175.
            var originalOpenDatabase = window.openDatabase;
            window.openDatabase = function(name, version, desc, size) {
                var db = null;
                try {
                    db = originalOpenDatabase(name, version, desc, size);
                } 
                catch (ex) {
                    db = null;
                }

                if (db === null) {
                    return storage.openDatabase(name, version, desc, size);
                }
                else {
                    return db;
                }
            };
        }
{code}


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