Kotlin Exposed Sum on condition (CaseWhenElse) - kotlin

Question

I have a table with data structure like :
id type cityName regDate
1249 0 City1 2019-10-01
I want to get result output of unique cities and the number of registrations in it per month as a list of data class objects of
data class NewClientsNumberCityMonth(
val cityName: String = "",
val januaryNewClientsNumber :Int = 0,
val februaryNewClientsNumber :Int = 0,
val marchNewClientsNumber :Int = 0,
val aprilNewClientsNumber :Int = 0,
val mayNewClientsNumber :Int = 0,
val juneNewClientsNumber :Int = 0,
val julyNewClientsNumber :Int = 0,
val augustNewClientsNumber :Int = 0,
val septemberNewClientsNumber :Int = 0,
val octoberNewClientsNumber :Int = 0,
val novemberNewClientsNumber :Int = 0,
val decemberNewClientsNumber :Int = 0
val total :Int = 0
)
and use this objects as the strings to fill the table (we dont know the number of unique cities),
result should be like :
City1 5 8 3 1 2 1 4 1 2 1 0 0
City2 69 23 7 5 3 10 24 14 12 23 25 10
...
im trying this
val tempMutList = mutableListOf<NewClientsNumberCityMonthModel>()
transaction(Connection.TRANSACTION_SERIALIZABLE, 2) {
addLogger(StdOutSqlLogger)
ClientsDataExposed
.slice(ClientsDataExposed.cityName)
.selectAll()
.groupBy(ClientsDataExposed.cityName)
.map { it[ClientsDataExposed.cityName] }
.toList().forEach {
val regsInCity = ClientsDataExposed
.slice(
ClientsDataExposed.id,
ClientsDataExposed.cityName,
ClientsDataExposed.type,
ClientsDataExposed.regDate,
ClientsDataExposed.regDate.month()
)
.selectAll()
.andWhere { ClientsDataExposed.cityName.eq(it) }
.andWhere {
ClientsDataExposed.regDate.between(
Date.valueOf("2019-01-01".toString()),
Date.valueOf("2020-01-01".toString())
)
}
.andWhere {
(ClientsDataExposed.type.inList(contracterTypeSelectedCheckboxes.filterValues { it }.keys.toList())) and (ClientsDataExposed.cityName.inList(
citiesSelectedChekboxes.filterValues { it }.keys.toList()
))
}
.map { it[ClientsDataExposed.regDate.month()] }
.toList()
val cityClientsPerMonth = NewClientsNumberCityMonthModel(
it,
regsInCity.count { it == 1 },
regsInCity.count { it == 2 },
regsInCity.count { it == 3 },
regsInCity.count { it == 4 },
regsInCity.count { it == 5 },
regsInCity.count { it == 6 },
regsInCity.count { it == 7 },
regsInCity.count { it == 8 },
regsInCity.count { it == 9 },
regsInCity.count { it == 10 },
regsInCity.count { it == 11 },
regsInCity.count { it == 12 },
regsInCity.count()
)
tempMutList.add(cityClientsPerMonth)
//obj of dataclass
}
viewTableTabOfnewClientsNumberCityMonth.value = tempMutList.map { it }
}
i know, that i should use Sum() and CaseWhenElse , like here , with check on
ClientsDataExposed.regDate.month()
which gives a month number (1-12), to assign the sum() result to my data class property, but i can't find any examples of CaseWhenElse syntax and i can't figure out it myself,
or may be there is another way of getting it whithout using of CaseWhenElse ?

Answer 1

Please check that code:
val monthExpr = ClientsDataExposed.regDate.month()
fun sumByMonth(monthNum: Int) = Expression.build {
val caseExpr = case().
When(monthExpr eq intLiteral(monthNum), intLiteral(1)).
Else(intLiteral(0))
Sum(caseExpr, IntegerColumnType())
}
val janSumExp = sumByMonth(1)
val febSumExp = sumByMonth(2)
ClientsDataExposed.
slice(ClientsDataExposed.cityName, janSumExp, febSumExp).
selectAll().
groupBy(ClientsDataExposed.id).map {
val janSum = it[janSumExp]
val febSum = it[febSumExp]
...
}