How to dynamically query the room database at runtime?

Question

The problem

Is it possible construct a query at runtime?

Use case

@Query(\"SELECT * FROM playlist \" +
        \"WHERE play         


        

Answer 1

Instead of writing multiple query i refer pass negative value to limit clause. Because if there is change in query i have to update the both query which is more error prone.

Official doc -> If the LIMIT expression evaluates to a negative value, then there is no upper bound on the number of rows returned. you can find it here https://sqlite.org/lang_select.html and read the limit clause section.

So I would do somthing like this,

@Query("SELECT * FROM playlist " +
    "WHERE playlist_title LIKE '% :playlistTitle %' " +
    "GROUP BY playlist_title " +
    "ORDER BY playlist_title " +
    "LIMIT :limit")
List searchPlaylists(String playlistTitle, int limit);

and pass negative when you don't want to apply filter.

return playlistDao.searchPlaylists(title, limit.isPresent() ? limit.get() : -1)

It's working in my case.

Updated [21 Dec 2018]

In case If you are using kotlin use default value.

@JvmOverloads
@Query("SELECT * FROM playlist " +
        "WHERE playlist_title LIKE '% :playlistTitle %' " +
        "GROUP BY playlist_title " +
        "ORDER BY playlist_title " +
        "LIMIT :limit")
fun searchPlaylists(playlistTitle: String, limit: Int = -1): List

@JvmOverloads to make it compatiable with Java. It generate two separate methods for Java.