How to update room database and How to get the insert status is working or completed? - android-room

Question

The first:
I've got dataList from retrofit And insert Room Database.
I want to change dataList(Like insert a element). My Room Database can work because I used OnConflictStrategy.REPLACE. but when I delete dataList some elements, My Room Database can not delete elements.
Dao:
#Insert (onConflict = OnConflictStrategy.REPLACE)
suspend fun insertData(dataList : List<Data>)
Entity:
#Entity
data class Data(
#PrimaryKey val Id : Long,
val Fl : String,
val FlMc : String,
val Dm : String,
val Mc : String,)
ViewModel:
fun insertData(dataList: List<Data>) = viewModelScope.launch {
dataRepository.insertData(dataList)
}
//get data from server
fun getData():LiveData<List<Data>>
Activity:
dataViewModel.getData().observer(this){
dataViewModel.insertData(it)
}
How to resolve this situation except DELETE ALL THEN INSERT
The second:
I want to use a progressbar to indicate that I am inserting dataList
How to get the insert status is working or completed

Answer 1

If I understand correctly, you issue is that you cannot delete because you are building a DataList item but don't know the primary key value as it's generated.
As you haven't shown the DataList entity then assuming it is like:-
#Entity
data class DataList(
#PrimaryKey(autogenerate = true)
val id: Long,
val othercolumns: String
....
)
and if you change from suspend fun insertData(dataList : List<Data>) to suspend fun insertData(dataList : List<Data>): List<Long> (i.e. added the List as the result)
Then you have the values of the id column in the result. In the case above the value is the value of the id column.
If the #PrimaryKey is not an integer type e.g. a String then the long returned WILL NOT be the value of the primary key. It will be a special value known as the rowid.
In short using an integer with primary key makes the column an alias of the rowid. if not an integer primary key then it is not an alias BUT the rowid still exists.
You can still use the rowid to access a specific row as the rowid MUST be a unique value. e.g. (again assuming the above) you could have an #Query such as
#Query("SELECT * FROM the_datalist_table WHERE rowid=:rowid")
suspend fun getDataListById(rowid: Long)
Only of use if you know the rowid though.
You could get rowid's say by using
#Query("SELECT rowid FROM the_datalist_table WHERE othercolumns LIKE :something")
suspend fun getRowidOfSomeDataLists(something: String): List<Long>
still not of great use as the selection criteria would also be able to provide a list of Datalists.
Additional re the comment:-
How to use in viewModel or Activity?
As an example you could do something like :-
fun insertData(dataList: List<Data>) = viewModelScope.launch {
val insertedDataList: ArrayList<Data> = ArrayList()
val insertedIdList = dataRepository.insertData(dataList)
val notInsertedDataList: ArrayList<Data> = ArrayList()
for(i in 0..insertedIdList.size) {
if (insertedIdList[i] > 0) {
insertedDataList.add(
Data(
insertedIdList[i], //<<<<< sets the id as per the returned list of id's
dataList[i].Fl,
dataList[i].FlMc,
dataList[i].Dm,
dataList[i].Mc)
)
} else {
notInsertedDataList.add(
Data(
insertedIdList[i], //<<<<< sets the id as per the returned list of id's WILL BE -1 as not inserted
dataList[i].Fl,
dataList[i].FlMc,
dataList[i].Dm,
dataList[i].Mc
)
)
}
}
val notInsertedCount = notInsertedDataList.size
val insertedCount = insertedDataList.size
}
So you have :-
insertedDataList an ArrayList of the successfully inserted Data's (id was not -1) with the id set accordingly.
notInsertedDataList an ArrayList of the Data's that were not inserted (id was -1) id will be set to -1.
insertedCount an Int with the number inserted successfully.
notInsertedCount and Int with the number not inserted correctly.
DELETE ALL
To delete all rows, unless you extract all rows you can't use the convenience #Delete, as this works on being provided the Object (Data) and selecting the row to delete according to the primary key (id column).
The convenience methods #Delete, #Update, #Insert are written to generate the underlying SQL statement(s) bases upon the object (Entity) passed.
e.g. #Delete(data: Data) would generate the SQL DELETE FROM data WHERE id=?, where ? would be the value of the id field when actually run.
The simpler way to delete all columns is to use the #Query annotation (which handles SQL statements other than SELECT statements). So you could have.
#Query("DELETE FROM data")
fun deleteAllData()
note that this does not the return the number of rows that have been deleted.