CODEWITHSUNDEEP
androidkotlinandroid-room
Amin Moradian
Amin Moradian

Reputation: 31

error: Query method parameters should either be a type that can be converted into a database column or a List / Array that contains such type

My Type Converter

import androidx.room.TypeConverter
import com.amin.movie.vo.Query

object QueryTypeConverter {
    @TypeConverter
    @JvmStatic
    fun queryToString(query: Query?): String? = if (query != null) Query.toJson(query) else null

    @TypeConverter
    @JvmStatic
    fun stringToQuery(data: String?): Query? = if (data != null) stringToQuery(data) else null
}

and Entity is

import androidx.room.Entity
import androidx.room.PrimaryKey
import androidx.room.TypeConverters
import com.amin.movie.db.MovieTypeConverters
import com.amin.movie.db.QueryTypeConverter
import com.google.gson.annotations.SerializedName

@Entity
@TypeConverters(QueryTypeConverter::class)
data class MovieSearchResult(
        // and other fields
        @PrimaryKey
        val query: Query
)

that error happend when i want make my project error: Query method parameters should either be a type that can be converted into a database column or a List / Array that contains such type. You can consider adding a Type Adapter for this.

Upvotes: 2

Views: 4404

Answers (2)

Rafay Rao
Rafay Rao

Reputation: 51

You must be probably using suspend with functions in Dao class. Remove those suspend keywords in Dao class

Old Code

@Insert
suspend fun insertdata(attendance: Attendance)

@Query("SELECT * FROM attendance")
suspend fun getdata(attendance: Attendance):LiveData<List<Attendance>>

New Code (Without Suspend Keyword)

@Insert
fun insertdata(attendance: Attendance)

@Query("SELECT * FROM attendance")
fun getdata(attendance: Attendance):LiveData<List<Attendance>>

Upvotes: 0

ZakCodes
ZakCodes

Reputation: 39

I've tested your code on the latest release of Room at this time and it works for me. I've created a Database and a Dao to make sure it works and everything seems fine.
Even though your method now works, this isn't the one they show in the kotlin examples in the Room documentation for kotlin. Here's their example on TypeConverter and this is how it would apply to your specific case (I've also provided the Database and Dao I've made):

// The query class wasn't provided so this is just a simple
// class with a toJson static method
data class Query(var query: String) {
    companion object {
        fun toJson(query: Query): String {
            return query.query
        }
    }
}

@Entity
@TypeConverters(QueryTypeConverter::class)
data class MovieSearchResult(
    // and other fields
    @PrimaryKey
    val query: Query
)

class QueryTypeConverter {
    @TypeConverter
    fun queryToString(query: Query?): String? = if (query != null) Query.toJson(query) else null

    @TypeConverter
    fun stringToQuery(data: String?): Query? = if (data != null) stringToQuery(data) else null
}

@Dao
interface MovieSearchResultDao {
    @Insert
    fun insert(r: MovieSearchResult)

    @Update
    fun update(r: MovieSearchResult)

    @Delete
    fun delete(r: MovieSearchResult)
}

@Database(entities=arrayOf(MovieSearchResult::class), version = 1, exportSchema = false)
abstract class AppDatabase : RoomDatabase() {
    abstract fun dao(): MovieSearchResultDao
    companion object {
        private var DB: AppDatabase? = null;
        public fun instance(context: Context): AppDatabase {
            var db = DB
            if (db == null) {
                db = Room.databaseBuilder(
                    context,
                    AppDatabase::class.java, "database-name"
                ).build()
                DB = db
            }
            return db
        }
    }
}

Upvotes: 1

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