Android Question Database file gets overwritten on app update

[rleiman]

Hi Everyone,

Is there a way I can upgrade my apps and not have the database storage files get overwritten when I give them an update to their apps?

I'm not using the database directly but using the KeyValues library.

 

[margret]

By default, Android will not overwrite your data files on a re-install or update. If your app directly copies a file, you need to make sure it will not copy over a file that already exist.

 

[eps]

Can you outline this a little more...

Is it the case that :

Ver 1.0 DB included, User installs App, DB gets moved to the read/write area for the App involved.

User adds some data.

Ver 2.0 DB included, User installs App, DB gets moved to the read/write area for the App involved.

All User data is effectively removed.

There are a number of different ways of handling this.

You could write the data to a file as well as the DB, so that when the App gets upgraded you capture this fact in your App and then re-add all the User data as well. This becomes a little more tricky if the User can add and remove data, but hopefully you get the idea. I do this for one of my Apps, but the User doesn't really add data in my App, they just indicate that records contained on one table are also on another table, their Favourites.

 

[margret]

You should have code to move or copy the file, only if it's not there already:

If File.Exists(File.DirInternal, "yourfilename") = False Then
     File.Copy(File.DirAssets, "yourfilename", File.DirInternal, "yourfilename")
End If

 

[rleiman]

Hi,

Thanks for the replies. With the help of Margret I changed my coding to this and it did not wipe out the data:

If FirstTime Then' This is the first time the app was run since installation.



' Show the user an hourglass while everything loads.

'------------------------------------------------------------

Activity.LoadLayout("PleaseWait")



PanelPleaseWait.Visible = True


DoEvents



' Set up default configuration settings.

'---------------------------------------

kvConfigurationSettings.Initialize(File.DirDefaultExternal, "kvConfigurationSettings", 1)

kvConfigurationSettings.PutSimple1("UserStoppedService", 0, "No")


' The data for the periods is stored as 9 items for each period.

' This will be loaded into a list the user can alter.

' Key: Period number 1, 2, etc.

' Index 0: Period description.

' Index 1: Period start time.

' Index 2: Peroid end time.

' Index 3: Day of week (Mon) active or inactive.

' Index 4: Day of week (Tue) active or inactive.

' Index 5: Day of week (Web) active or inactive.

' Index 6: Day of week (Thu) active or inactive.

' Index 7: Day of week (Fri) active or inactive.

' Index 8: Day of week (Sat) active or inactive.

' Index 9: Day of week (Sun) active or inactive.

'---------------------------------------------------------------


kvSchoolPeriods.Initialize(File.DirDefaultExternal, "kvSchoolPeriods", 10)



If File.Exists(File.DirDefaultExternal, "kvSchoolPeriods") = False Then



kvSchoolPeriods.PutSimple1("0", 0, "")

kvSchoolPeriods.PutSimple1("0", 1, "")

kvSchoolPeriods.PutSimple1("0", 2, "")

kvSchoolPeriods.PutSimple1("0", 3, "Active")

kvSchoolPeriods.PutSimple1("0", 4, "Active")

kvSchoolPeriods.PutSimple1("0", 5, "Active")

kvSchoolPeriods.PutSimple1("0", 6, "Active")

kvSchoolPeriods.PutSimple1("0", 7, "Active")

kvSchoolPeriods.PutSimple1("0", 8, "Inactive")

kvSchoolPeriods.PutSimple1("0", 9, "Inactive")



kvSchoolPeriods.PutSimple1("1", 0, "")

kvSchoolPeriods.PutSimple1("1", 1, "")

kvSchoolPeriods.PutSimple1("1", 2, "")

kvSchoolPeriods.PutSimple1("1", 3, "Active")

kvSchoolPeriods.PutSimple1("1", 4, "Active")

kvSchoolPeriods.PutSimple1("1", 5, "Active")

kvSchoolPeriods.PutSimple1("1", 6, "Active")

kvSchoolPeriods.PutSimple1("1", 7, "Active")

kvSchoolPeriods.PutSimple1("1", 8, "Inactive")

kvSchoolPeriods.PutSimple1("1", 9, "Inactive")



kvSchoolPeriods.PutSimple1("2", 0, "")

kvSchoolPeriods.PutSimple1("2", 1, "")

kvSchoolPeriods.PutSimple1("2", 2, "")

kvSchoolPeriods.PutSimple1("2", 3, "Active")

kvSchoolPeriods.PutSimple1("2", 4, "Active")

kvSchoolPeriods.PutSimple1("2", 5, "Active")

kvSchoolPeriods.PutSimple1("2", 6, "Active")

kvSchoolPeriods.PutSimple1("2", 7, "Active")

kvSchoolPeriods.PutSimple1("2", 8, "Inactive")

kvSchoolPeriods.PutSimple1("2", 9, "Inactive")

EndIf



' This is the main menu screen.

'------------------------------

LoadMainLayout

 

[eps]

What happens if you update the DB held with the App, or will this never happen?

 

[rleiman]

Hi,

The user of the app saves the school period details and that's stored in the database. I updated the database and re-installed the app and the new updated data was still there when I viewed the data within the app.

 

[eps]

No worries, but beware if you need to change the database structure or add a new table or column for instance. You will then need to try and manage that, but it might never happen for your software