how to deal with indices info during ROOM migration

Question

CODE:

@Entity(tableName = "UserRepo", indices = @Index(value = "id", unique = true))
public class GitHubRepo {
@PrimaryKey(autoGenerate = true)
public int _id;
public int id;
public String name;
public String description;
@Embedded
public RepoOwner owner;

public GitHubRepo(int id, String name, String description, RepoOwner owner) {
    this.id = id;
    this.name = name;
    this.description = description;
    this.owner = owner;
}

public class RepoOwner {
@ColumnInfo(name = "user_id")
public int id;
public String login;

public RepoOwner(int id, String login) {
    this.id = id;
    this.login = login;
}

Explain: I hava a ROOM database which contains a simple table UserRepo, this table contains three columns _id, id, name and use the "id" as the index in order to have a faster query. For now, I want to use the @Embedded annotation to add the owner info in this table. The Migration code is follow:

public static final Migration MIGRATION_1_2 = new Migration(1, 2) {
    @Override
    public void migrate(@NonNull SupportSQLiteDatabase database) {
        database.execSQL("ALTER TABLE UserRepo ADD COLUMN user_id INTEGER");
        database.execSQL("ALTER TABLE UserRepo ADD COLUMN login TEXT");
    }
};

During the migration, I got an error of:

Expected: TableInfo

{name='UserRepo', columns={name=Column{name='name', type='TEXT', notNull=false, primaryKeyPosition=0}, description=Column{name='description', type='TEXT', notNull=false, primaryKeyPosition=0}, _id=Column{name='_id', type='INTEGER', notNull=true, primaryKeyPosition=1}, id=Column{name='id', type='INTEGER', notNull=true, primaryKeyPosition=0}, login=Column{name='login', type='TEXT', notNull=false, primaryKeyPosition=0}, user_id=Column{name='user_id', type='INTEGER', notNull=false, primaryKeyPosition=0}}, foreignKeys=[], **indices=[Index{name='index_UserRepo_id', unique=true, columns=[id]}]**}

Found: TableInfo

{name='UserRepo', columns={name=Column{name='name', type='TEXT', notNull=false, primaryKeyPosition=0}, description=Column{name='description', type='TEXT', notNull=false, primaryKeyPosition=0}, _id=Column{name='_id', type='INTEGER', notNull=true, primaryKeyPosition=1}, id=Column{name='id', type='INTEGER', notNull=true, primaryKeyPosition=0}, login=Column{name='login', type='TEXT', notNull=false, primaryKeyPosition=0}, user_id=Column{name='user_id', type='INTEGER', notNull=false, primaryKeyPosition=0}}, foreignKeys=[], **indices=[]**}

Seems I lost the indices info in my Migration implement, How can I fix this?

ANOTHER INFO I can fix this issue by remove the indices info from the GitHubRepo entity, But I don't want to do this, as I don't want to lose the advantage of indices.

Answer 1

Finally, I fixed this issue by set an index for this table in Migrate.So the code is:

 public static final Migration MIGRATION_1_2 = new Migration(1, 2) {
    @Override
    public void migrate(@NonNull SupportSQLiteDatabase database) {
        database.execSQL("ALTER TABLE UserRepo ADD COLUMN user_id INTEGER");
        database.execSQL("ALTER TABLE UserRepo ADD COLUMN login TEXT");
        database.execSQL("CREATE UNIQUE INDEX index_UserRepo_id ON UserRepo (id)");
    }
};

The third SQL line is the key.