Room automatically sorts on the basis of primary k

问题:

I have a data class like this

@Entity
data class Question(

        @field:SerializedName("question")
        var question: String? = null,

        @field:SerializedName("answers")
        var answers: ArrayList<String?>? = null,

        @field:SerializedName("id")
        @PrimaryKey
        var id: Int? = null
)

Then in DAO I have saving and getting methods like this

    @Dao
interface QnADao {

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    fun saveQuestion(questions:Question)

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    fun saveAllQuestions(questions: List<Question?>?)


    @Query("SELECT * from Question")
    fun getAllQnA():List<Question>


}

I am saving a list of Questions and then later on retrieving them. So whenever I retrieve them I get the list sorted according to the id which is the primary key.

So if I am saving questions with id:254, id:23, id:45 and id:92 then I am getting it like this id:23, id:45, id:92 and id:254

But I don't need a sorted list like that, I need to get the data as it was saved in the database. Any help would be appreciated. Thanks.

回答1:

Try to use autoGenerate = true for primary key so it will create PK number in sequence

See below lines

@PrimaryKey(autoGenerate = true)

So that now your insert and retrive order will be same

回答2:

You can add a Date field to your Question entity

@field:SerializedName("date")
var date: Date? = null,

and order your entities by date

@Query("SELECT * FROM Question ORDER BY date DESC")