How to migrate Realm in Android

Question

So recently I got into a giant issue of how to migrate stuff in Realm. I finally solved the problem, so I decided to post it on stackoverflow. Please note that Realm is upgrading their system very soon, so the answer will probably soon be outdated.

The code is for Realm 80.3.

Answer 1

This is the code I used:

try {
    realm = Realm.getInstance(context, "database.realm");
    Log.i("Database2", context.getFilesDir().getPath());
} catch (RealmMigrationNeededException ex) {
    Realm.migrateRealmAtPath(context.getFileStreamPath("database.realm").getPath(), new RealmMigration() {
        @Override
        public long execute(Realm realm, long version) {
            Log.i("Database", "Yay!");
            // Migrate stuff...
            Table table = realm.getTable(RealmTestObjectTwo.class);
            table.addColumn(ColumnType.INTEGER, "key");
            table.addColumn(ColumnType.STRING, "value");
            table.setPrimaryKey("key");
            version += 1;
            // End Migrate Stuff...
            return version;
        }
    });
}

The thing that got me was that Realm expects you to provide the full path to the database file.

Hopefully this post will help someone!

Answer 2

Following class may help you to migrate realm database tables (0.86.0+)

public class Migration
        implements RealmMigration {
    @Override
    public void migrate(final DynamicRealm realm, long oldVersion, long newVersion) {
        Log.e("TAG", oldVersion + "-" + newVersion);
        RealmSchema realmSchema = realm.getSchema();
        if(oldVersion == 0) {
            realmSchema.get("FestivalModel").addField("timestamp", Long.class, FieldAttribute.REQUIRED);
            oldVersion++;
        }
        if(oldVersion == 1) {
            //add new fields - match_image,lineup_image,festival_end_date,isMatchedFestival
            RealmObjectSchema festivalscema = realmSchema.get("FestivalModel");

            List<String> list = new ArrayList<>(festivalscema.getFieldNames());
            Log.e("Fields", list.toString());
            festivalscema
                    .addField("isMatchedFestival", Integer.class, FieldAttribute.REQUIRED)
                    .addField("match_image", String.class)
                    .addField("lineup_image", String.class)
                    .addField("festival_end_date", String.class)

                    .transform(new RealmObjectSchema.Function() {
                        @Override
                        public void apply(DynamicRealmObject obj) {
                            //obj.set("isMatchedFestival", "1");
                            DynamicRealmObject festivalModel = realm.createObject("FestivalModel");
                            festivalModel.setInt("name", 1);

                        }
                    });

            // Create a new class - ArtistFestivalModel
            RealmObjectSchema artistFestivalModelSchema = realmSchema.create("ArtistFestivalModel")
                    .addField("id", String.class, FieldAttribute.PRIMARY_KEY)
                    .addField("name", String.class)
                    .addField("description", String.class)
                    .addField("profile_image", String.class)
                    .addField("match_image", String.class)
                    .addField("lineup_image", String.class)
                    .addField("festival_date", String.class)
                    .addField("festival_end_date", String.class)
                    .addField("official_url", String.class)
                    .addField("address", String.class)
                    .addField("latitude", Double.class, FieldAttribute.REQUIRED)
                    .addField("longitude", Double.class, FieldAttribute.REQUIRED)
                    .addField("created_date", String.class)
                    .addField("modified_date", String.class)
                    .addField("is_deleted", String.class)
                    .addField("timestamp", Long.class, FieldAttribute.REQUIRED);

            // Create a new class - ArtistFestivalModel
            RealmObjectSchema festivalLineupSchema = realmSchema.create("FestivalLineup")
                    .addField("id", String.class, FieldAttribute.PRIMARY_KEY)
                    .addField("name", String.class)
                    .addField("profile_image", String.class)
                    .addField("official_url", String.class)
                    .addField("created_date", String.class)
                    .addField("modified_date", String.class)
                    .addField("is_deleted", String.class)
                    .addField("lineup", String.class)
                    .addField("FestivalId", String.class)
                    .addField("is_liked", Boolean.class, FieldAttribute.REQUIRED);

            /** 1st uploaded version with 0
             *  2nd uploaded version with 1
             *  3rd uploaded version with 19
             */
            oldVersion = 19;
        }
        if(oldVersion == 20) {
            //add new fields - match_image,lineup_image,festival_end_date,isMatchedFestival
            RealmObjectSchema festivalscema = realmSchema.get("FestivalModel");
            List<String> list = new ArrayList<>(festivalscema.getFieldNames());
            Log.e("Fields", list.toString());
            festivalscema
                    .addField("isMatchedFestival", Integer.class, FieldAttribute.REQUIRED)
                    .addField("match_image", String.class)
                    .addField("lineup_image", String.class)
                    .addField("festival_end_date", String.class)
                    .transform(new RealmObjectSchema.Function() {
                        @Override
                        public void apply(DynamicRealmObject obj) {
                            //obj.set("isMatchedFestival", "1");
                            DynamicRealmObject festivalModel = realm.createObject("FestivalModel");
                            festivalModel.setInt("name", 1);
                        }
                    });

            // Create a new class - ArtistFestivalModel

            RealmObjectSchema artistFestivalModelSchema = realmSchema.create("ArtistFestivalModel")
                    .addField("id", String.class, FieldAttribute.PRIMARY_KEY)
                    .addField("name", String.class)
                    .addField("description", String.class)
                    .addField("profile_image", String.class)
                    .addField("match_image", String.class)
                    .addField("lineup_image", String.class)
                    .addField("festival_date", String.class)
                    .addField("festival_end_date", String.class)
                    .addField("official_url", String.class)
                    .addField("address", String.class)
                    .addField("latitude", Double.class, FieldAttribute.REQUIRED)
                    .addField("longitude", Double.class, FieldAttribute.REQUIRED)
                    .addField("created_date", String.class)
                    .addField("modified_date", String.class)
                    .addField("is_deleted", String.class)
                    .addField("timestamp", Long.class, FieldAttribute.REQUIRED);

            // Create a new class - ArtistFestivalModel

            RealmObjectSchema festivalLineupSchema = realmSchema.create("FestivalLineup")
                    .addField("id", String.class, FieldAttribute.PRIMARY_KEY)
                    .addField("name", String.class)
                    .addField("profile_image", String.class)
                    .addField("official_url", String.class)
                    .addField("created_date", String.class)
                    .addField("modified_date", String.class)
                    .addField("is_deleted", String.class)
                    .addField("lineup", String.class)
                    .addField("FestivalId", String.class)
                    .addField("is_liked", Boolean.class, FieldAttribute.REQUIRED);

            /** 1st uploaded version with 0
             *  2nd uploaded version with 1
             *  3rd uploaded version with 19
             */
            oldVersion++;
        }
    }
}