RealmMigrationNeededException on fresh install after model change

[adamsp]

I'm working on integrating Realm in my Android application. My model changes from time-to-time during development, so I expect the RealmMigrationNeededException when this happens. I uninstall the app (adb uninstall my.package.name), and then fresh install - but still get the exception.

I can fix it by:

adb shell run-as my.package.name rm files/default.realm files/default.realm.lock

Shouldn't these be removed when I uninstall the app? I suspect this isn't a Realm issue but rather something to do with Android or adb - however I haven't had this issue with say, ORMLite. Any ideas?

Edit: I actually get this exception even if I don't change the model at all.

[zaki50]

Hi @adamsp

RealmConfiguration(https://realm.io/docs/java/latest/api/io/realm/RealmConfiguration.html) has deleteRealmIfMigrationNeeded method.
If you call this method when creating RealmConfiguration, Realm file will be deleted instead of throwing RealmMigrationNeededException.

RealmConfiguration config = new RealmConfiguration.Builder(context)
    .deleteRealmIfMigrationNeeded()
    .build()

Does this help?

[adamsp]

That certainly makes things easier! I'll stick with this for now, but I still find it curious that Android doesn't appear to delete all files in the directory on an app uninstall. Hopefully this helps someone else.

[adamsp]

5 months later I've finally figured this out as I check things off my pre-release TODO list.

This was caused by Android 6.0 auto-backup. I had to disable this for my Realm files (I'm using the default configuration):

<manifest ...
    <application ...
        android:fullBackupContent="@xml/backup">
    ....
</manifest>

And res/xml/backup.xml:

<?xml version="1.0" encoding="utf-8"?>
<full-backup-content>
    <exclude domain="file" path="default.realm"/>
    <exclude domain="file" path="default.realm.lock"/>
</full-backup-content>

[thready]

Adam, I owe you a beer. I was pulling my hair out and then came across your article: http://speakman.net.nz/blog/2016/04/21/handling-realmmigrationneededexception-on-a-fresh-installation-on-android/

Thank you very much!