Android 中的领域迁移问题

Question

I have a DB which contains few new columns added. As per my understanding, When someone creates the App for the first time, the default schema version set to 0. Later which we need to increment.

What I have done is, I have set the SCHEMA_VERSION = 1 as there is a new change in the schema and expecting the freshly installed app on any device will contain the default schema as 1.

I am testing with two different devices, one is running Android 6.0 (Marshmellow) another one is Android 8.0 (Oreo).

Problem is , when running the app in 6.0, I get the default schema is set as -1 for the first time. Later when I set explicitly Schema Version 1, it sets the default as 1 which is as expected and not calling the Migration as it is installed on the device for the first time.

RealmConfiguration.Builder builder = new RealmConfiguration.Builder();
    builder.schemaVersion(SCHEMA_VERSION); // SCHEMA_VERSION = 1
    builder.migration(new Migration());

Realm.setDefaultConfiguration(builder.build());
Realm.getDefaultInstance().close();

But when I am trying the same code in 8.0, I am getting default schema is set as 0 and when I am setting

builder.schemaVersion(SCHEMA_VERSION); // SCHEMA_VERSION = 1 

,the Migration() is getting called and throwing Field already exists as it is considering SCHEMA_VERSION = 1 is the update.

Which means, in 8.0 even if we install the app for the first time, it is taking care that SCHEMA_VERSION = 0 is the default one with all of columns added (Because I can see the db already got the columns added).

What could be wrong? Why there are two different Default Schema versions (-1 & 0) on fresh App in two devices? And in any case if it is installed on a device for the first time, why would the migration get called?

This is the code snippet which I am using before setting the SCHEMA_VERSION to get the Default Schema Versions..

DynamicRealm dynamicRealm = DynamicRealm.getInstance(Realm.getDefaultConfiguration());
long version = dynamicRealm.getVersion();
dynamicRealm.close();

I also have searched SO Q&As, read articles but could not find anything matches my problem. Kindly track the issue here . Would be very grateful if someone could explain what went wrong and how to fix.. Thanks. :)

Answer 1

I have figured out, the device Samsung Note 8, started working after restarting the device. Before that, I tried to uninstall and re-install back the application and I am pretty sure I removed everything possible. Which did not work and started calling the Migration. Now this is not occurring anymore and works perfectly. :)