How to get OnConflictStrategy return value from DAO

Question

I am using Room Persistence Library. The operation works as expected. But how do I get onConflict value from DAO back from calling method. I get the following error

error: Not sure how to handle the insert method's return type.

Update After I change return type from Integer to long, I get this error

Not sure how to handle update method's return type. Currently the supported return types are void, int or Int.

In DAO.java

@Dao
public interface UserDao {

    @Insert(onConflict = OnConflictStrategy.ABORT)
    long insert(UserEntity userEntity);

    @Update(onConflict = OnConflictStrategy.IGNORE)
    long update(UserEntity userEntity);
}

In MainActivity.java

@Override
protected Void doInBackground(UserEntity... userEntities) {
    long result = userDao.insert(userEntities[0]);
    if(result == OnConflictStrategy.ABORT){
        result = userDao.update(userEntities[0]);

    }
    return null;
}

see this https://stackoverflow.com/questions/44364240/android-room-get-the-id-of-new-inserted-row-with-auto-generate — iamkdblue, Jun 04 '19 at 06:50
@kdblue i tried changing from Integer to Long as suggested, it showing error above. See my updated question — KIRPAL SINGH, Jun 04 '19 at 07:06

Arka Prava Basu · Accepted Answer · 2019-06-04T07:27:16.163

2

In case of ConflictStrategy.ABORT Room will throw a SQLiteConstraintException. You can catch that to fit your use case.

The compilation error you are getting is due to the fact @Insert operations can return long, long[] or void only. Integer will not do.

@Update will return the number of rows updated by the query. This method will return an int or void. Doc: https://www.sqlite.org/lang_update.html

edited Jun 04 '19 at 07:27

answered Jun 04 '19 at 06:51

Arka Prava Basu

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When i change Integer to long, i get this. error: Not sure how to handle update method's return type. Currently the supported return types are void, int or Int. – KIRPAL SINGH Jun 04 '19 at 06:58
Are you using Kotlin or Java? `Int` has no meaning in Java. – Arka Prava Basu Jun 04 '19 at 07:08
i am using java – KIRPAL SINGH Jun 04 '19 at 07:10
https://www.sqlite.org/rowidtable.html . This clearly states rowIds are signed 64 bit integers.. – Arka Prava Basu Jun 04 '19 at 07:14
Are you sure u are using `long` and not `Long`? – Arka Prava Basu Jun 04 '19 at 07:15
`Not sure how to handle update method's return type. Currently the supported return types are void, int or Int.` This say `update method's` return type. Please post the `@Update` contract – Arka Prava Basu Jun 04 '19 at 07:18
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/194413/discussion-between-kirpal-singh-and-arka-prava-basu). – KIRPAL SINGH Jun 04 '19 at 07:19
I have updated my code to include Update interface method – KIRPAL SINGH Jun 04 '19 at 07:22
1

Answer updated. Update method will return the no of rows updated with is limited by 32 bit integer in SQLite – Arka Prava Basu Jun 04 '19 at 07:27

score 1 · Answer 2 · answered Jun 04 '19 at 07:28

Insert If the @Insert method receives only 1 parameter, it can return a long, which is the new rowId for the inserted item. If the parameter is an array or a collection, it should return long[] or List instead.

Update Although usually not necessary, you can have this method return an int value instead, indicating the number of rows updated in the database.

After reading multiple time, i understood the methods are returning number of records instead of error code. Anyway my question regarding how OnConflictStrategy values are read or used is still unanswered

U cant "read" its value. As answered if ABORT it will throw an SQLiteConstraintException. Source: https://commonsware.com/AndroidArch/previews/room-and-conflict-resolution Need to find out of the other states. — Arka Prava Basu, Jun 04 '19 at 07:38

How to get OnConflictStrategy return value from DAO

2 Answers2