I am trying to get the user ID from the newest user. How can I make the insert method spit the ID when the ID is autogenerated?
in Model
#PrimaryKey(autoGenerate = true)
val userId: Int
in Dao
#Insert(onConflict = OnConflictStrategy.REPLACE)
fun addUserWithLong(user: User): LiveData<Long>
in Repository
fun addUserWitLong(user: User): LiveData<Long> {
return userDao.addUserWithLong(user)
}
in ViewModel
fun addUserWithLong(user: User): LiveData<Long> {
return repository.addUserWitLong(user)
}
in Fragment
val id: Long? = userViewModel.addUserWithLong(user).value
I have read in the docs that #Insert returns Long as the row ID but I do not know how to program it. Now the error is "Not sure how handle insert method return type." Is there some way to make with LiveData and not with Rxjava. That is without the need to download more dependecies.
As per the documentation here
If the #Insert method receives a single parameter, it can return a
long value, which is the new rowId for the inserted item. If the
parameter is an array or a collection, then the method should return
an array or a collection of long values instead, with each value as
the rowId for one of the inserted items. To learn more about returning
rowId values, see the reference documentation for the #Insert
annotation, as well as the SQLite documentation for rowid tables
So you can use it like
#Insert(onConflict = OnConflictStrategy.REPLACE)
long addUserWithLong(user: User)
or if you are inserting a list
#Insert(onConflict = OnConflictStrategy.REPLACE)
long[] addUserWithLong(user: List<User>)
Edit-1
After checking answers from this post.
No, you can't. I wrote an answer to the issue. The reason is, that
LiveData is used to notify for changes. Insert, Update, Delete won't
trigger a change.
I just created a test project and successfully received Id of last inserted item in activity. Here is my implementation.
Dao
#Insert
suspend fun addUser(user: Users): Long
Repo
suspend fun insertUser(context: Context, users: Users): Long {
val db = AppDatabase.getInstance(context)
val dao = db.userDao()
return dao.addUser(users)
}
ViewModel
fun addUser(context: Context, users: Users) = liveData {
//you can also emit your customized object here.
emit("Inserting...")
try {
val userRepo = UsersRepo()
val response = userRepo.insertUser(context, users)
emit(response)
} catch (e: Exception) {
e.printStackTrace()
emit(e.message)
}
}
Activity
viewModel.addUser(applicationContext, user).observe(this, Observer { userId ->
Log.d("MainActivity", "Inserted User Id is $userId")
})
Check test application here.
I want to know that how can i sum value in the room database .
Let say i have insert this value (10,000) in the room database and i want to insert new value to database (20,000) and i want the new value to be sum with old value not replace it .
how can i do that .?
example of code :
Database Table :
#entity
class sum (
id : int ,
value : Long )
Dao :
#insert (onConflict = OnConflictStrategy.REPLACE)
suspend fun insert (model :sum)
what shoud i use instead of above insert .
#Query("SELECT * FROM sum")
fun getall () : LiveData<sum>
and in activity :
late init var : viewmodel : Viewmodeldatabase
val textvalue : TextView
viewmodel = Viewmodelprovider(this).get(Viewmodeldatabase::class.java)
textvalue = findvidwbyid(R.id.text)
viewmodel.insert(sum(1 , 10000)
// when the above value insert , if there is an old value sum with it and not replace it or remove it
viewmodel.getall.observe(this , Observer {
textvalue.text = it.value
)}
thank's guys for watch my code and help me .
Try to add next method in your dao:
#Query("UPDATE sum SET value = value + :addValue WHERE id =:id")
suspend fun updateSum(id: Int, addValue: Long)
Then you can call it from your ViewModel/Activity
UPDATE
For single method for update/insert put these methods in dao:
#Insert(onConflict = OnConflictStrategy.REPLACE)
suspend fun insertSum(model: Sum)
#Query("UPDATE sum SET value = value + :value WHERE id = :id")
suspend fun updateSum(id: Int, value: Long)
#Query("SELECT * FROM sum WHERE id = :id")
suspend fun getSumById(id: Int): Sum?
#Transaction
suspend fun updateOrInsertSum(sum: Sum) { // <-- this method updates value or insert new item, if id is not found
getSumById(sum.id)?.let { updateSum(sum.id, sum.value) } ?: insertSum(sum)
}
Of course you should add method updateOrInsertSum to your repository and viewmodel as well
Then if you call for id = '1' for the first time value will be inserted:
viewmodel.updateOrInsertSum(Sum(1 ,10000)) // <-- id = 1, value = 10000
On the next call item will be updated with the same method:
viewmodel.updateOrInsertSum(Sum(1 ,20000)) // <-- id = 1, value = 10000+2000
In your Dao, I see that you use the function getAll(),
lets say that you save them into a list of integers
val list: List<Int>//list holding all of you data returned in the onChanged method of the observer callback(or the lambda callback in case of Kotlin)
lets say that you want to update the value at position 1:
#Update
public void update(newVal: Int);
and when calling the update function pass to it the summation of the old value coming from the "list" I mentioned earlier and the newValue
database.dao.update(list[1] + newValue)
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.
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
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")
I'm using room in my new Android app, and I'm trying to update an a model object's property at runtime, but it doesn't seem to get saved.
Entity
#Entity(tableName = "sessions")
data class Session(#ColumnInfo(name="id") #PrimaryKey(autoGenerate = true) var id: Int = 0,
#ColumnInfo(name="date") var date: Date,
#ColumnInfo(name="repetitions_completed") var repetitionsCompleted: Int,
#ColumnInfo(name="squeeze_time_per_rep") var squeezeTimePerRep: Int,
#ColumnInfo(name="finishing_repetitions_completed") var finishingRepetitionsCompleted: Int,
#ColumnInfo(name="finishing_squeeze_time_per_rep") var finishingSqueezeTimePerRep: Int)
In my app I'm using it like this
session = Session(0,date,0,slowSeconds,0,quickSeconds)
sessionDao.insertAll(sessionDB)
...
session.repetitionsCompleted = totalSlowReps
session.finishingRepetitionsCompleted = totalQuickReps
sessionDao.updateSessions(session)
The problem is that session's property values like repetitionsCompleted and finishingRepetitionsCompleted doesn't seem to be saved, and it always remain 0 when I restart the app. updateSessions also returns 0
Here is the code for the Dao
#Dao
interface SessionDao {
// https://developer.android.com/training/data-storage/room/accessing-data#query-params
#Query("SELECT * FROM sessions")
fun getAll(): List<Session>
#Query("SELECT * FROM sessions WHERE date BETWEEN :from AND :to")
fun getSessionsBetween(from: Date, to: Date): List<Session>
#Query("SELECT * FROM sessions ORDER BY date LIMIT 1")
fun getOldestSession(): List<Session>
#Update
fun updateSessions(vararg sessions: Session) : Int
#Insert
fun insertAll(vararg sessions: Session)
}
What's weirder is that update seems to work in my unit test, but not in the actual app code.
I don't know if this affects things, but I'm running this in a service.
I figured it out, the problem was that when I created the session object, object is returned with an id set to 0 rather than its autoGenerate primary key, so what I did was alter the insert to return it's inserted id
#Insert
fun insertAll(vararg sessions: Session) : List<Long>
When I create my session, I manually reassign its ID
sessionDB = Session(0,date,0,slowSeconds,0,quickSeconds)
val insertID = sessionDao.insertAll(sessionDB).first().toInt()
sessionDB.id = insertID
maybe it sounds a little stupid but it fixed my issue. I guess all of you are familiar with the OnConflictStrategy. it's making sense to set strategy for insert. but google need this strategy for #Update as well as the default strategy is ABORT.
#return How to handle conflicts. Defaults to {#link OnConflictStrategy#ABORT}.
so the solution would be.
#Update(onConflict = OnConflictStrategy.REPLACE)
Maybe you're not sending the class id.
the value #PrimaryKey of the #Entity Class
Android's Room persistence library graciously includes the #Insert and #Update annotations that work for objects or collections. I however have a use case (push notifications containing a model) that would require an UPSERT as the data may or may not exist in the database.
Sqlite doesn't have upsert natively, and workarounds are described in this SO question. Given the solutions there, how would one apply them to Room?
To be more specific, how can I implement an insert or update in Room that would not break any foreign key constraints? Using insert with onConflict=REPLACE will cause the onDelete for any foreign key to that row to be called. In my case onDelete causes a cascade, and reinserting a row will cause rows in other tables with the foreign key to be deleted. This is NOT the intended behavior.
EDIT:
as #Tunji_D mentioned,
Room officially supports #Upsert from version 2.5.0-alpha03. (release note)
please check his answer for more details.
OLD ANSWER:
Perhaps you can make your BaseDao like this.
secure the upsert operation with #Transaction,
and try to update only if insertion is failed.
#Dao
public abstract class BaseDao<T> {
/**
* Insert an object in the database.
*
* #param obj the object to be inserted.
* #return The SQLite row id
*/
#Insert(onConflict = OnConflictStrategy.IGNORE)
public abstract long insert(T obj);
/**
* Insert an array of objects in the database.
*
* #param obj the objects to be inserted.
* #return The SQLite row ids
*/
#Insert(onConflict = OnConflictStrategy.IGNORE)
public abstract List<Long> insert(List<T> obj);
/**
* Update an object from the database.
*
* #param obj the object to be updated
*/
#Update
public abstract void update(T obj);
/**
* Update an array of objects from the database.
*
* #param obj the object to be updated
*/
#Update
public abstract void update(List<T> obj);
/**
* Delete an object from the database
*
* #param obj the object to be deleted
*/
#Delete
public abstract void delete(T obj);
#Transaction
public void upsert(T obj) {
long id = insert(obj);
if (id == -1) {
update(obj);
}
}
#Transaction
public void upsert(List<T> objList) {
List<Long> insertResult = insert(objList);
List<T> updateList = new ArrayList<>();
for (int i = 0; i < insertResult.size(); i++) {
if (insertResult.get(i) == -1) {
updateList.add(objList.get(i));
}
}
if (!updateList.isEmpty()) {
update(updateList);
}
}
}
For more elegant way to do that I would suggest two options:
Checking for return value from insert operation with IGNORE as a OnConflictStrategy (if it equals to -1 then it means row wasn't inserted):
#Insert(onConflict = OnConflictStrategy.IGNORE)
long insert(Entity entity);
#Update(onConflict = OnConflictStrategy.IGNORE)
void update(Entity entity);
#Transaction
public void upsert(Entity entity) {
long id = insert(entity);
if (id == -1) {
update(entity);
}
}
Handling exception from insert operation with FAIL as a OnConflictStrategy:
#Insert(onConflict = OnConflictStrategy.FAIL)
void insert(Entity entity);
#Update(onConflict = OnConflictStrategy.FAIL)
void update(Entity entity);
#Transaction
public void upsert(Entity entity) {
try {
insert(entity);
} catch (SQLiteConstraintException exception) {
update(entity);
}
}
EDIT:
Starting in version 2.5.0-alpha03, Room now has support for an #Upsert annotation.
An example of its use can be seen in this pull request in the "Now in Android" sample app.
OLD ANSWER:
I could not find a SQLite query that would insert or update without causing unwanted changes to my foreign key, so instead I opted to insert first, ignoring conflicts if they occurred, and updating immediately afterwards, again ignoring conflicts.
The insert and update methods are protected so external classes see and use the upsert method only. Keep in mind that this isn't a true upsert as if any of the MyEntity POJOS have null fields, they will overwrite what may currently be in the database. This is not a caveat for me, but it may be for your application.
#Insert(onConflict = OnConflictStrategy.IGNORE)
protected abstract void insert(List<MyEntity> entities);
#Update(onConflict = OnConflictStrategy.IGNORE)
protected abstract void update(List<MyEntity> entities);
#Transaction
public void upsert(List<MyEntity> entities) {
insert(models);
update(models);
}
If the table has more than one column, you can use
#Insert(onConflict = OnConflictStrategy.REPLACE)
to replace a row.
Reference - Go to tips Android Room Codelab
This is the code in Kotlin:
#Insert(onConflict = OnConflictStrategy.IGNORE)
fun insert(entity: Entity): Long
#Update(onConflict = OnConflictStrategy.REPLACE)
fun update(entity: Entity)
#Transaction
fun upsert(entity: Entity) {
val id = insert(entity)
if (id == -1L) {
update(entity)
}
}
Just an update for how to do this with Kotlin retaining data of the model (Maybe to use it in a counter as in example):
//Your Dao must be an abstract class instead of an interface (optional database constructor variable)
#Dao
abstract class ModelDao(val database: AppDatabase) {
#Insert(onConflict = OnConflictStrategy.FAIL)
abstract fun insertModel(model: Model)
//Do a custom update retaining previous data of the model
//(I use constants for tables and column names)
#Query("UPDATE $MODEL_TABLE SET $COUNT=$COUNT+1 WHERE $ID = :modelId")
abstract fun updateModel(modelId: Long)
//Declare your upsert function open
open fun upsert(model: Model) {
try {
insertModel(model)
}catch (exception: SQLiteConstraintException) {
updateModel(model.id)
}
}
}
You can also use #Transaction and database constructor variable for more complex transactions using database.openHelper.writableDatabase.execSQL("SQL STATEMENT")
I found an interesting reading about it here.
It is the "same" as posted on https://stackoverflow.com/a/50736568/4744263. But, if you want an idiomatic and clean Kotlin version, here you go:
#Transaction
open fun insertOrUpdate(objList: List<T>) = insert(objList)
.withIndex()
.filter { it.value == -1L }
.forEach { update(objList[it.index]) }
#Insert(onConflict = OnConflictStrategy.IGNORE)
abstract fun insert(obj: List<T>): List<Long>
#Update
abstract fun update(obj: T)
Alternatively to make UPSERT manually in loop like it's suggested in #yeonseok.seo post, we may use UPSERT feature provided by Sqlite v.3.24.0 in Android Room.
Nowadays, this feature is supported by Android 11 and 12 with default Sqlite version 3.28.0 and 3.32.2 respectively. If you need it in versions prior Android 11 you can replace default Sqlite with custom Sqlite project like this https://github.com/requery/sqlite-android (or built your own) to have this and other features that are available in latest Sqlite versions, but not available in Android Sqlite provided by default.
If you have Sqlite version starting from 3.24.0 on device, you can use UPSERT in Android Room like this:
#Query("INSERT INTO Person (name, phone) VALUES (:name, :phone) ON CONFLICT (name) DO UPDATE SET phone=excluded.phone")
fun upsert(name: String, phone: String)
Another approach I can think of is to get the entity via DAO by query, and then perform any desired updates.
This may be less efficient compared to the other solutions in this thread in terms of runtime because of having to retrieve the full entity, but allows much more flexibility in terms of operations allowed such as on what fields/variable to update.
For example :
private void upsert(EntityA entityA) {
EntityA existingEntityA = getEntityA("query1","query2");
if (existingEntityA == null) {
insert(entityA);
} else {
entityA.setParam(existingEntityA.getParam());
update(entityA);
}
}
Here is a way to use a real UPSERT clause in Room library.
The main advantage of this method is that you can update rows for which you don't know their ID.
Setup Android SQLite support library in your project to use modern SQLite features on all devices:
Inherit your daos from BasicDao.
Probably, you want to add in your BasicEntity: abstract fun toMap(): Map<String, Any?>
Use UPSERT in your Dao:
#Transaction
private suspend fun upsert(entity: SomeEntity): Map<String, Any?> {
return upsert(
SomeEntity.TABLE_NAME,
entity.toMap(),
setOf(SomeEntity.SOME_UNIQUE_KEY),
setOf(SomeEntity.ID),
)
}
// An entity has been created. You will get ID.
val rawEntity = someDao.upsert(SomeEntity(0, "name", "key-1"))
// An entity has been updated. You will get ID too, despite you didn't know it before, just by unique constraint!
val rawEntity = someDao.upsert(SomeEntity(0, "new name", "key-1"))
BasicDao:
import android.database.Cursor
import androidx.room.*
import androidx.sqlite.db.SimpleSQLiteQuery
import androidx.sqlite.db.SupportSQLiteQuery
abstract class BasicDao(open val database: RoomDatabase) {
/**
* Upsert all fields of the entity except those specified in [onConflict] and [excludedColumns].
*
* Usually, you don't want to update PK, you can exclude it in [excludedColumns].
*
* [UPSERT](https://www.sqlite.org/lang_UPSERT.html) syntax supported since version 3.24.0 (2018-06-04).
* [RETURNING](https://www.sqlite.org/lang_returning.html) syntax supported since version 3.35.0 (2021-03-12).
*/
protected suspend fun upsert(
table: String,
entity: Map<String, Any?>,
onConflict: Set<String>,
excludedColumns: Set<String> = setOf(),
returning: Set<String> = setOf("*")
): Map<String, Any?> {
val updatableColumns = entity.keys
.filter { it !in onConflict && it !in excludedColumns }
.map { "`${it}`=excluded.`${it}`" }
// build sql
val comma = ", "
val placeholders = entity.map { "?" }.joinToString(comma)
val returnings = returning.joinToString(comma) { if (it == "*") it else "`${it}`" }
val sql = "INSERT INTO `${table}` VALUES (${placeholders})" +
" ON CONFLICT(${onConflict.joinToString(comma)}) DO UPDATE SET" +
" ${updatableColumns.joinToString(comma)}" +
" RETURNING $returnings"
val query: SupportSQLiteQuery = SimpleSQLiteQuery(sql, entity.values.toTypedArray())
val cursor: Cursor = database.openHelper.writableDatabase.query(query)
return getCursorResult(cursor).first()
}
protected fun getCursorResult(cursor: Cursor, isClose: Boolean = true): List<Map<String, Any?>> {
val result = mutableListOf<Map<String, Any?>>()
while (cursor.moveToNext()) {
result.add(cursor.columnNames.mapIndexed { index, columnName ->
val columnValue = if (cursor.isNull(index)) null else cursor.getString(index)
columnName to columnValue
}.toMap())
}
if (isClose) {
cursor.close()
}
return result
}
}
Entity example:
import androidx.room.ColumnInfo
import androidx.room.Entity
import androidx.room.Index
import androidx.room.PrimaryKey
#Entity(
tableName = SomeEntity.TABLE_NAME,
indices = [Index(value = [SomeEntity.SOME_UNIQUE_KEY], unique = true)]
)
data class SomeEntity(
#PrimaryKey(autoGenerate = true)
#ColumnInfo(name = ID)
val id: Long,
#ColumnInfo(name = NAME)
val name: String,
#ColumnInfo(name = SOME_UNIQUE_KEY)
val someUniqueKey: String,
) {
companion object {
const val TABLE_NAME = "some_table"
const val ID = "id"
const val NAME = "name"
const val SOME_UNIQUE_KEY = "some_unique_key"
}
fun toMap(): Map<String, Any?> {
return mapOf(
ID to if (id == 0L) null else id,
NAME to name,
SOME_UNIQUE_KEY to someUniqueKey
)
}
}
#Upsert is now available in room Version 2.5.0-beta01
check out the release notes
Should be possible with this sort of statement:
INSERT INTO table_name (a, b) VALUES (1, 2) ON CONFLICT UPDATE SET a = 1, b = 2
If you have legacy code: some entities in Java and BaseDao as Interface (where you cannot add a function body) or you too lazy for replacing all implements with extends for Java-children.
Note: It works only in Kotlin code. I'm sure that you write new code in Kotlin, I'm right? :)
Finally a lazy solution is to add two Kotlin Extension functions:
fun <T> BaseDao<T>.upsert(entityItem: T) {
if (insert(entityItem) == -1L) {
update(entityItem)
}
}
fun <T> BaseDao<T>.upsert(entityItems: List<T>) {
val insertResults = insert(entityItems)
val itemsToUpdate = arrayListOf<T>()
insertResults.forEachIndexed { index, result ->
if (result == -1L) {
itemsToUpdate.add(entityItems[index])
}
}
if (itemsToUpdate.isNotEmpty()) {
update(itemsToUpdate)
}
}