Room user configurable order by queries

Question

I am migrating an app to use Room from normal Sqlite and one part that I am having trouble with is that there are several queries that have an orde

Answer 1

As tyczj already suggested you can us a RawQuery. In addition, the SimpleSQLiteQuery can also be moved into the DAO so there are no SQL statements outside of the DAO.

A DAO can also be defined via an abstract class. This allows you to add a method which executes the SimpleSQLiteQuery.

Example:

@DAO
public abstract class UserDao {

    @RawQuery
    public abstract List getUsersViaRawQuery(SupportSQLiteQuery query);

    public List getUsersOrderBy(String column) {
        String statement = "SELECT * FROM user ORDER BY " + column + " ASC";
        SupportSQLiteQuery query = new SimpleSQLiteQuery(statement, new Object[]{});
        return getUsersViaRawQuery(query);
    }

}

The column parameter could also be replaced by an enum, which only allows specific values.

Example:

private static String createOrderByString(Order order) {
    switch (order) {
        case NAME:
            return "ORDER BY first_name ASC, last_name ASC";
        case AGE:
            return "ORDER BY age DESC";
        default:
            return "";
    }
}