I'm trying to get data from the database using Room, I want to get the data in the format {registration_number, List, List} but I'm getting an error:
"Cannot find the parent entity column area_name in ... and my intermediate class"
and in fact I hide that maybe I am taking the wrong approach, please guide me, because I am new in this area
to extract the data I use an intermediate class
my class is:
data class LastConfiscats(
#ColumnInfo(name = "registration_number")
var slaugh_num: String,
// #ColumnInfo(name = "area_name",
#Relation(entity = Area::class, parentColumn = "area_name", entityColumn = "name")
var areaName: List<String>,
// #ColumnInfo(name = "confiscation_name")
#Relation(entity = Confiscation::class, parentColumn = "confiscation_name", entityColumn = "name")
var confiscationName: List<String>
and DAO method to select data:
#Query("SELECT registration_number, area.[name] AS area_name, confiscations.[name] AS confiscation_name " +
"FROM car_body, car_body_confiscations" +
"INNER JOIN area ON car_body_confiscations.area_id == area.id " +
"INNER JOIN confiscations ON car_body_confiscations.confiscation_id == confiscations.id " +
"WHERE car_body.id == car_body_confiscations.car_body_id ORDER BY car_body.id DESC LIMIT :row_count")
fun getLastConfiscats(row_count: Int): LiveData<List<LastConfiscats>>
The linkage scheme between the tables that I am trying to implement is as follows:
There are examples on the internet how to make a relationship between 2 tables but I need to create a relationship between 4 tables.
Please help me to get the data in the right way
UPDATE :
My Area entity is:
#Entity(tableName = "area")
data class Area( #PrimaryKey(autoGenerate = true) var id: Int?, var name: String? )
but in my Confiscation entity I also have "name" column:
#Entity(tableName = "confiscations")
data class Confiscation( #PrimaryKey(autoGenerate = true) var id: Int?, var name: String? )
The actual message you are getting is because when you use #Relation the parent MUST exist and be annotated with #Embedded.
The parent and entity columns MUST be columns in the respective classes.
As an example the following will enable you to get a List of Confiscations, with the related CarBody and the respective Areas (note colum names based upon the screen shots):-
data class LastConfiscats(
#Embedded
var carBodyConfiscations: Car_Body_Confiscations,
#Relation(entity = CarBody::class, parentColumn = "car_body_id", entityColumn = "id")
var carBody: CarBody,
#Relation(entity = Area::class, parentColumn = "areaId", entityColumn = "id")
var area: List<Area>
)
You could use the above with a query such as:-
#Query("SELECT * FROM Car_Body_Confiscations")
fun getCardBodyJoinedWithStuff(): List<LastConfiscats>
No JOINS needed. That is because Room builds the underlying SQL. First is basically the copy of the supplied query. After retrieving the Car_Body_Confiscations it then uses queries based upon the field names/#ColumnInfo and runs queries for each Car_Body_Connfiscation.
For each #Relationship it populates the respective fields (1 carBody and the List of Areas) using queries that it builds. Here's and example of part of the code, for the above from the java(generated) for the query above :-
Main (parent query)
#Override
public List<LastConfiscats> getCardBodyJoinedWithStuff() {
final String _sql = "SELECT * FROM Car_Body_Confiscations";
final RoomSQLiteQuery _statement = RoomSQLiteQuery.acquire(_sql, 0);
....
Later Nn (getting the CarBody(s) there will only be 1)
StringBuilder _stringBuilder = StringUtil.newStringBuilder();
_stringBuilder.append("SELECT `id`,`registrationNumber`,`datetime`,`userId`,`testId` FROM `CarBody` WHERE `id` IN (");
final int _inputSize = _map.size();
Even Later On (Areas)
StringBuilder _stringBuilder = StringUtil.newStringBuilder();
_stringBuilder.append("SELECT `id`,`name` FROM `Area` WHERE `id` IN (");
Now if you want to code your own JOINS etc and alias columns then you will have to consider a few things.
The receiving class MUST be able to be built from the result set and thus column names MUST match the fields in the POJO (unless using #Prefix annotation).
You also need to be aware that the result set will be the cartesian product, thus in the case of doing the above, bypassing how Room does it, the for each combination/permutation of confiscation/carbody/area you get a row (unless grouped/excluded by where clause). So if you have 1 confiscation joined to 1 car but with 10 areas then you would get 10 rows all with the same confiscation and carbody.
You may wish to consider having a look at Room #Relation annotation with a One To Many relationship. Which explains this a little more and includes an example of using a JOINs
Additional - User and TestLists
You may well want to include the CarBody's User and the Test_Lists so you have a result with all of the related data.
This needs to be looked at from a hierarchical perspective. That is the confiscation has a direct link/reference/map to the CarBody but underneath that are the links/references/mappings to the User from the CarBody and to the Test_Lists.
So to incorporate this you need a POJO for a CarBody with it's User and it's Test_Lists. So, for example:-
data class CarBodyWithUserAndWithTestList(
#Embedded
var carBody: CarBody,
#Relation(
entity = Users::class,
parentColumn = "userId",
entityColumn = "id"
)
var users: Users,
#Relation(
entity = Test_List::class,
parentColumn = "testId",
entityColumn = "id"
)
var testList: List<Test_List>
)
With this you can then amend the LastConfiscats to include a CarBodyWithUserAndWithTestList instead of just a CarBody e.g.:
data class LastConfiscats(
#Embedded
var carBodyConfiscations: Car_Body_Confiscations,
#Relation(entity = CarBody::class, parentColumn = "car_body_id", entityColumn = "id")
//var carBody: CarBody, /* REMOVED */
var carBodyWithUserAndWithTestList: CarBodyWithUserAndWithTestList, /* ADDED */
#Relation(entity = Area::class, parentColumn = "areaId", entityColumn = "id")
var area: List<Area>
)
Note that the #Relation has the CarBody class as the entity. That is because the CarBody is the class that needs to be inspected in order for Room to ascertain the columns used for the links/references/,mappings.
*Working Example/Demo
Here's the entire code for a Working example that inserts some data into all the tables and then extracts the data using the getCardBodyJoinedWithStuff query, it then writes the data to the Log.
the code includes ForeignKey constraints which enforces and helps to maintain referential integrity.
for id's Long rather than Int has been used as Long properly reflects the potential size of the field/value.
autoGenerate = true has not been used as this is inefficient and not needed see https://sqlite.org/autoinc.html, which includes as the very first statement The AUTOINCREMENT keyword imposes extra CPU, memory, disk space, and disk I/O overhead and should be avoided if not strictly needed. It is usually not needed. (autoGenerate = true results in AUTOINCREMENT)
So all the classes/interfaces :-
#Entity(
foreignKeys = [
ForeignKey(
Users::class,
parentColumns = ["id"],
childColumns = ["userId"],
onDelete = ForeignKey.CASCADE,
onUpdate = ForeignKey.CASCADE
),
ForeignKey(
Test_List::class,
parentColumns = ["id"],
childColumns = ["testId"],
onDelete = ForeignKey.CASCADE,
onUpdate = ForeignKey.CASCADE
)
]
)
data class CarBody(
#PrimaryKey
var id: Long?=null,
var registrationNumber: Int,
var datetime: String,
#ColumnInfo(index = true)
var userId: Long,
#ColumnInfo(index = true)
var testId: Long
)
#Entity
data class Users(
#PrimaryKey
var id:Long?=null,
var name: String,
var lastName: String,
var email: String,
var password: String
)
#Entity
data class Test_List(
#PrimaryKey
var id: Long?=null,
var date: String,
var is_saved: Boolean
)
#Entity(
foreignKeys = [
ForeignKey(
entity = CarBody::class,
parentColumns = ["id"],
childColumns = ["car_body_id"],
onDelete = ForeignKey.CASCADE,
onUpdate = ForeignKey.CASCADE
),
ForeignKey(
entity = Confiscation::class,
parentColumns = ["id"],
childColumns = ["confiscation_id"],
onDelete = ForeignKey.CASCADE,
onUpdate = ForeignKey.CASCADE
),
ForeignKey(
entity = Area::class,
parentColumns = ["id"],
childColumns = ["areaId"],
onDelete = ForeignKey.CASCADE,
onUpdate = ForeignKey.CASCADE
)
]
)
data class Car_Body_Confiscations(
#PrimaryKey
var id: Long?=null,
#ColumnInfo(index = true)
var car_body_id: Long,
#ColumnInfo(index = true)
var confiscation_id: Long,
#ColumnInfo(index = true)
var areaId: Long
)
#Entity
data class Area(
#PrimaryKey
var id: Long?=null,
var name: String
)
#Entity
data class Confiscation(
#PrimaryKey
var id: Long?=null,
var name: String
)
#Dao
interface AllDao {
#Insert(onConflict = OnConflictStrategy.IGNORE)
fun insert(area: Area): Long
#Insert(onConflict = OnConflictStrategy.IGNORE)
fun insert(carBodyConfiscations: Car_Body_Confiscations): Long
#Insert(onConflict = OnConflictStrategy.IGNORE)
fun insert(carBody: CarBody): Long
#Insert(onConflict = OnConflictStrategy.IGNORE)
fun insert(confiscation: Confiscation): Long
#Insert(onConflict = OnConflictStrategy.IGNORE)
fun insert(users: Users): Long
#Insert(onConflict = OnConflictStrategy.IGNORE)
fun insert(testList: Test_List): Long
#Transaction
#Query("SELECT * FROM Car_Body_Confiscations")
fun getCardBodyJoinedWithStuff(): List<LastConfiscats>
}
#Database(entities = [
Area::class,
Car_Body_Confiscations::class,
CarBody::class,
Confiscation::class,
Users::class,
Test_List::class
],
exportSchema = false, version = 1)
abstract class TheDatabase: RoomDatabase() {
abstract fun getAllDao(): AllDao
companion object {
private var instance: TheDatabase?=null
fun getInstance(context: Context): TheDatabase {
if (instance==null) {
instance = Room.databaseBuilder(context,TheDatabase::class.java,"the_database.db")
.allowMainThreadQueries()
.build()
}
return instance as TheDatabase
}
}
}
data class LastConfiscats(
#Embedded
var carBodyConfiscations: Car_Body_Confiscations,
#Relation(entity = Confiscation::class, parentColumn = "confiscation_id", entityColumn = "id")
var confiscation: Confiscation,
#Relation(entity = CarBody::class, parentColumn = "car_body_id", entityColumn = "id")
//var carBody: CarBody, /* REMOVED */
var carBodyWithUserAndWithTestList: CarBodyWithUserAndWithTestList, /* ADDED */
#Relation(entity = Area::class, parentColumn = "areaId", entityColumn = "id")
var area: List<Area>
)
data class CarBodyWithUserAndWithTestList(
#Embedded
var carBody: CarBody,
#Relation(
entity = Users::class,
parentColumn = "userId",
entityColumn = "id"
)
var users: Users,
#Relation(
entity = Test_List::class,
parentColumn = "testId",
entityColumn = "id"
)
var testList: List<Test_List>
)
The following activity code (note that main thread used for brevity and convenience):-
class MainActivity : AppCompatActivity() {
lateinit var db: TheDatabase
lateinit var dao: AllDao
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
db = TheDatabase.getInstance(this)
dao = db.getAllDao()
dao.insert(Users(100,"Fred","Bloggs","fredBloggs#mail.com","password"))
dao.insert(Users(200,"Jane","Doe","janeDoe#email.org","password"))
/* example where id is autogenerated */
val marySmithId = dao.insert(Users(name = "Mary", lastName = "Smith", email = "marysmith#mailit.co.uk", password = "1234567890"))
dao.insert(Test_List(1,"2022-01-01",false))
dao.insert(Test_List(2,"2022-02-02",true))
dao.insert(CarBody(1000,1234,"2022-01-01",100 /* Fred Bloggs*/,2 ))
dao.insert(CarBody(2000,4321,"2021-12-05",100,1))
dao.insert(CarBody(3000,1111,"2021-09-10",200,2))
dao.insert(Area(100,"Area100"))
dao.insert(Area(200,"Area200"))
dao.insert(Area(300,"Area300"))
dao.insert(Area(400,"Area400"))
dao.insert(Confiscation(901,"C1"))
dao.insert(Confiscation(902,"C2"))
dao.insert(Confiscation(903,"C3"))
dao.insert(Confiscation(904,"C4"))
dao.insert(Car_Body_Confiscations(500,1000,901,100))
dao.insert(Car_Body_Confiscations(510,2000,904,400))
dao.insert(Car_Body_Confiscations(520,3000,902,300))
/* Extract the data and output to the Log */
for(cbc in dao.getCardBodyJoinedWithStuff()) {
val areaList = StringBuilder()
for (a in cbc.area) {
areaList.append("\n\t\tArea is ${a.name} ID is ${a.id}")
}
val testList = StringBuilder()
testList.append("\n\t\tThere are ${cbc.carBodyWithUserAndWithTestList.testList.size} TestLists, they are:")
for (t in cbc.carBodyWithUserAndWithTestList.testList) {
testList.append("\n\t\t\t${t.date} Save is ${t.is_saved} ID is ${t.id}")
}
Log.d(
"DBINFO",
"CBC ID =${cbc.carBodyConfiscations.id}" +
"\n\tConfiscation Name is ${cbc.confiscation.name}" +
"\n\tAreas (there is/are ${cbc.area.size}) they are $areaList}" +
"\n\tCarBody Reg is ${cbc.carBodyWithUserAndWithTestList.carBody.registrationNumber} " +
"Date is ${cbc.carBodyWithUserAndWithTestList.carBody.datetime}" +
"\n\t\tUser is ${cbc.carBodyWithUserAndWithTestList.users.name}" +
",${cbc.carBodyWithUserAndWithTestList.users.lastName} " +
"email is ${cbc.carBodyWithUserAndWithTestList.users.email}" +
"$testList"
)
}
}
}
Result
The Log after running:-
D/DBINFO: CBC ID =500
Confiscation Name is C1
Areas (there is/are 1) they are
Area is Area100 ID is 100}
CarBody Reg is 1234 Date is 2022-01-01
User is Fred,Bloggs email is fredBloggs#mail.com
There are 1 TestLists, they are:
2022-02-02 Save is true ID is 2
D/DBINFO: CBC ID =510
Confiscation Name is C4
Areas (there is/are 1) they are
Area is Area400 ID is 400}
CarBody Reg is 4321 Date is 2021-12-05
User is Fred,Bloggs email is fredBloggs#mail.com
There are 1 TestLists, they are:
2022-01-01 Save is false ID is 1
D/DBINFO: CBC ID =520
Confiscation Name is C2
Areas (there is/are 1) they are
Area is Area300 ID is 300}
CarBody Reg is 1111 Date is 2021-09-10
User is Jane,Doe email is janeDoe#email.org
There are 1 TestLists, they are:
2022-02-02 Save is true ID is 2
Re the Comment
I actually have a Cartesian product, I had to process it somehow, although I do not know how yet.
You may find that the above is fine and processes the product pretty easily.
Where Room's relationship handling can become restrictive is if you want to selectively retrieve related data. The way Room handles #Relation means that it retrieves ALL children irrespective of any JOINS and WHERE clauses. They are only effective if they affect the result of the topmost parent.
In your case, where you don't actually cater for lists (such as multiple users per carbody) then Room should suffice.
The original Query - revisited
Changing your query a little to (largely to suit the previous classes ) to:-
#Query("SELECT " +
"registrationNumber, " +
"area.[name] AS area_name, " +
"confiscation.[name] AS confiscation_name " +
"FROM carbody, car_body_confiscations " +
"INNER JOIN area ON car_body_confiscations.areaId == area.id " +
"INNER JOIN confiscation ON car_body_confiscations.confiscation_id == confiscation.id " +
"WHERE carbody.id == car_body_confiscations.car_body_id " +
"ORDER BY carbody.id DESC " +
"LIMIT :row_count"
)
fun getLastConfiscats(row_count: Int): /*LiveData<*/List<MyQueryPOJO>/*>*/
see the following re MyQueryPOJO
And adding a suitable class (no #Embeddeds or #Relations needed, so Room doesn't get confused with column names) :-
data class MyQueryPOJO(
/* The output columns of the query */
var registrationNumber: Int,
#ColumnInfo(name = "area_name")
var not_the_area_name: String,
var confiscation_name: String
)
note how the not_the_area_name field has the #ColumnInfo annotation to tell it to use the area_name output column
In the activity, using:-
for (mqo in dao.getLastConfiscats(10)) {
Log.d("DBINFO","Reg = ${mqo.registrationNumber} Confiscation = ${mqo.confiscation_name} Area Name = ${mqo.not_the_area_name}")
}
Results in (with the same data) :-
D/DBINFO: Reg = 1111 Confiscation = C2 Area Name = Area300
D/DBINFO: Reg = 4321 Confiscation = C4 Area Name = Area400
D/DBINFO: Reg = 1234 Confiscation = C1 Area Name = Area100
as the relationships all all basically 1-1 (the references are back to front for a 1-many) the cartesian product is fine as there will not be any duplicates.
I'm using Room for persistence in my app. I have a Player table, which has a name and matchesPlayed column.
When a match is played by a Player, I would like to increment matchesPlayed if it was played by an existing Player, or create a new Player otherwise. In order to determine this, I created a SQL query getPlayerByName(name: String) which should return us the Player if it exists. When I run the query in the Database Inspector in Android Studio, everything works fine. However, when I run the same query in the app, it fails. Does anybody know what I'm doing wrong?
Player.kt
#Entity(tableName = "players")
data class Player(
#PrimaryKey val id: String,
val name: String,
#ColumnInfo(name = "matches_played") val matchesPlayed: String,
#ColumnInfo(name = "matches_won") val matchesWon: String
)
PlayerDao.kt
#Dao
interface PlayerDao {
#Query("SELECT * FROM $PLAYER_TABLE_NAME")
fun getAll(): Single<List<Player>>
#Query("SELECT * FROM $PLAYER_TABLE_NAME WHERE name = :name LIMIT 1")
fun getPlayerByName(name: String): Maybe<Player>
#Insert(onConflict = OnConflictStrategy.REPLACE)
fun insert(player: Player): Completable
}
PlayerViewModel.kt
#HiltViewModel
class PlayerViewModel #Inject constructor(
private val playerRepository: PlayerRepositoryImpl
) : ViewModel() {
...
private fun findAndInsertPlayer(
playerName: String,
playerWon: Boolean
) {
viewModelScope.launch {
val increment = if (playerWon) 1 else 0
playerRepository.getPlayerByName(playerName)
.subscribe(
{ player ->
// Handle Success
},
{
// Somehow, this block always gets called
}
)
}
)
}
I have the following object:
#Entity(tableName = "Section", primaryKeys = ["sectionID","number","numberOfServers"])
data class Section(
#ColumnInfo(name = "number")
var number: Int,
#ColumnInfo(name = "numberOfServer")
var numberOfServers: Int
){
#ColumnInfo(name = "sectionID")
var id: Long = 0
}
then I have the DAO method to insert into room as such:
#Insert(onConflict = OnConflictStrategy.IGNORE)
suspend fun insertSection(section: Section): Long
My goal is for an insert operation to be ignored if a Section object with the same pair of number and numberOfServers already exists in the database. In addition I want the section to have an id which is autogenerated by room. I have seen posts that use indexes and the unique attribute to achieve the composite primary key part of my goal and then use the #PrimaryKey(autogenerate = true) to generate the id. However I am not sure that using indexes works the same as primaryKeys does. As far as I see it if I use indexes and set those to unique room will check
if(index1 != unique){
ignore
}else if(index2 != unique){
ignore
...
etc.
while what I want is more of a
if((index1 && index2 combination) != unique){
ignore
}
It seems that indexes do offer the functionality I need according to the documentation and so I ended up with this:
#Entity(tableName = "Section", indices = [Index(value = ["number","numberOfServer"], unique = true)])
data class Section(
#ColumnInfo(name = "number")
var number: Int,
#ColumnInfo(name = "numberOfServer")
var numberOfServers: Int
){
#PrimaryKey(autoGenerate = true)
#ColumnInfo(name = "sectionID")
var id: Long = 0
}
Thank you for participating
I am trying to convert my code as clean as possible using the Kotlin's built-in functions. I have done some part of the code using for loops. But I want to know the efficient built-in functions to be used for this application
I have two array lists accounts and cards.
My goal is to search a specific card with the help of its card-number, in the array list named cards.
Then I have to validate the pin. If the pin is correct, by getting that gift card's customerId I have to search the account in the array list named accounts. Then I have to update the balance of the account.
These are the class which I have used
class Account{
constructor( )
var id : String = generateAccountNumber()
var name: String? = null
set(name) = if (name != null) field = name.toUpperCase() else { field = "Unknown User"; println("invalid details\nAccount is not Created");}
var balance : Double = 0.0
set(balance) = if (balance >= 0) field = balance else { field = 0.0 }
constructor(id: String = generateAccountNumber(), name: String?,balance: Double) {
this.id = id
this.balance = balance
this.name = name
}
}
class GiftCard {
constructor( )
var cardNumber : String = generateCardNumber()
var pin: String? = null
set(pin) = if (pin != null) field = pin else { field = "Unknown User"; println("Please set the pin\nCard is not Created");}
var customerId : String = ""
set(customerId) = if (customerId != "") field = customerId else { field = "" }
var cardBalance : Double = 0.0
set(cardBalance) = if (cardBalance > 0) field = cardBalance else { field = 0.0; println("Card is created with zero balance\nPlease deposit") }
var status = Status.ACTIVE
constructor(cardNumber: String = generateCardNumber(),
pin: String,
customerId: String,
cardBalance: Double = 0.0,
status: Status = Status.ACTIVE){
this.cardNumber = cardNumber
this.pin = pin
this.customerId = customerId
this.cardBalance = cardBalance
this.status = status
}
}
This is the part of code, I have to be changed :
override fun closeCard(cardNumber: String, pin: String): Pair<Boolean, Boolean> {
for (giftcard in giftcards) {
if (giftcard.cardNumber == cardNumber) {
if (giftcard.pin == pin) {
giftcard.status = Status.CLOSED
for (account in accounts)
account.balance = account.balance + giftcard.cardBalance
giftcard.cardBalance = 0.0
return Pair(true,true)
}
\\invalid pin
return Pair(true,false)
}
}
\\card is not present
return Pair(false,false)
}
Both classes are not very idiomatic. The primary constructor of a Kotlin class is implicit and does not need to be defined, however, you explicitly define a constructor and thus you add another one that is empty.
// good
class C
// bad
class C {
constructor()
}
Going further, Kotlin has named arguments and default values, so make use of them.
class Account(
val id: String = generateAccountNumber(),
val name: String = "Unknown User",
val balance: Double = 0.0
)
Double is a very bad choice for basically anything due to its shortcomings, see for instance https://www.floating-point-gui.de/ Choosing Int, Long, heck even BigDecimal would be better. It also seems that you don’t want the balance to ever go beneath zero, in that case consider UInt and ULong.
Last but not least is the mutability of your class. This can make sense but it also might be dangerous. It is up to you to decide upon your needs and requirements.
enum class Status {
CLOSED
}
#ExperimentalUnsignedTypes
class Account(private var _balance: UInt) {
val balance get() = _balance
operator fun plusAssign(other: UInt) {
_balance += other
}
}
#ExperimentalUnsignedTypes
class GiftCard(
val number: String,
val pin: String,
private var _status: Status,
private var _balance: UInt
) {
val status get() = _status
val balance get() = _balance
fun close() {
_status = Status.CLOSED
_balance = 0u
}
}
#ExperimentalUnsignedTypes
class Main(val accounts: List<Account>, val giftCards: List<GiftCard>) {
fun closeCard(cardNumber: String, pin: String) =
giftCards.find { it.number == cardNumber }?.let {
(it.pin == pin).andAlso {
accounts.forEach { a -> a += it.balance }
it.close()
}
}
}
inline fun Boolean.andAlso(action: () -> Unit): Boolean {
if (this) action()
return this
}
We change the return type from Pair<Boolean, Boolean> to a more idiomatic Boolean? where Null means that we did not find anything (literally the true meaning of Null), false that the PIN did not match, and true that the gift card was closed. We are not creating a pair anymore and thus avoid the additional object allocation.
The Boolean.andAlso() is a handy extension function that I generally keep handy, it is like Any.also() from Kotlin’s STD but only executes the action if the Boolean is actually true.
There's probably a million different ways to do this, but here's one that at least has some language features I feel are worthy to share:
fun closeCard(cardNumber: String, pin: String): Pair<Boolean, Boolean> {
val giftCard = giftcards.find { it.cardNumber == cardNumber }
?: return Pair(false, false)
return if (giftCard.pin == pin) {
giftCard.status = Status.CLOSED
accounts.forEach {
it.balance += giftCard.cardBalance
}
Pair(true, true)
} else
Pair(true, false)
}
The first thing to notice if the Elvis operator - ?: - which evaluates the right side of the expression if the left side is null. In this case, if find returns null, which is equivalent to not finding a card number that matches the desired one, we'll immediately return Pair(false, false). This is the last step in your code.
From there one it's pretty straight forward. If the pins match, you loop through the accounts list with a forEach and close the card. If the pins don't match, then we'll go straight to the else branch. In kotlin, if can be used as an expression, therefore we can simply put the return statement before the if and let it return the result of the last expression on each branch.
PS: I won't say this is more efficient than your way. It's just one way that uses built-in functions - find and forEach - like you asked, as well as other language features.
PPS: I would highly recommend to try and find another way to update the lists without mutating the objects. I don't know your use cases, but this doesn't feel too thread-safe. I didn't post any solution for this, because it's outside the scope of this question.