error when using Kotlin groupBy function applied to list - dictionary

Question

I'm very new in Kotlin, and I can't seem to figure out how to do something that is really quite simple; grouping my data by the name field. I've tried with map and groupBy, using one or using both, but I either get an error, or the data is in a list, and the duplicates are filtered out - which I don't want. I need the duplicates grouped.
As an aside, my sql function (in the repository), which finds records in my DB based on the date entered has fields from two different classes, which isn't the optimal way of doing things, but I didn't know how else to combine the data from two tables. I don't mind correcting that if someone can tell me how. The error that I get is "Type inference failed. Expected Type mismatch. Required: List Found Map
String?, List>
below is my code
TIA
my repository code
#Query("SELECT new XXX.report.model.ReportWithBatches(r.adlsPath, r.fileSize, r.lastUpdate, r.remoteFileName, b.dataPath , b.version, b.dataSource, r.recordCount, r.transferStatus, r.businessDate) FROM ReportOutput r INNER JOIN BatchInput b ON r.job.jobUuid = b.reportJob.jobUuid WHERE r.businessDate = ?1")
fun findAllByBusinessDateJoinBatches(date: LocalDate): List<ReportWithBatches>
}
my service code
fun findAllByCreationDateJoinBatches(date: LocalDate): List<ReportWithBatches> {
val reportBatchesList = reportRepository.findAllByBusinessDateJoinBatches(date)
return reportBatchesList.groupBy({it.adlsFullPath}, {it})
// .map { it.value }
// return reportBatchesList
// return reportBatchesList.map { rB ->
// ReportWithBatches(
// rB.adlsFullPath,
// rB.contentLength,
// rB.lastModified,
// rB.remoteFileName,
// rB.dataPath,
// rB.version,
// rB.source,
// rB.numberOfRecords,
// rB.transferStatus,
// rB.creationDate)
//
// }
}
code in my controller
#GetMapping(value = ["/linkBatches/{today}"])
fun findAllByCreationDateJoinBatches(#PathVariable("today") #DateTimeFormat(pattern = "yyyyMMdd") date: LocalDate): List<ReportWithBatches> {
return eligibleService.findAllByCreationDateJoinBatches(date)
}
My result is this - note there's only one batch per record in the result:
[
{
"adlsFullPath": "part-00000-1399b2e0-5fa5-484b-91f1-9dec0601b885-c000.csv.gz",
"contentLength": 20,
"lastModified": "2020-02-07T16:50:16.132-05:00",
"remoteFileName": null,
"dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=3/version=1",
"version": 1,
"source": "NETS",
"numberOfRecords": -1,
"transferStatus": "REPORT_CREATED",
"creationDate": "2020-02-07"
},
{
"adlsFullPath": "part-00007-1399b2e0-5fa5-484b-91f1-9dec0601b885-c000.csv.gz",
"contentLength": 1104,
"lastModified": "2020-02-07T16:50:16.133-05:00",
"remoteFileName": null,
"dataPath": "preprd/datalake/lake/nes/negotiation/execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=3/version=1",
"version": 1,
"source": "NETS",
"numberOfRecords": -1,
"transferStatus": "REPORT_CREATED",
"creationDate": "2020-02-07"
},
{
"adlsFullPath": "part-00015-1399b2e0-5fa5-484b-91f1-9dec0601b885-c000.csv.gz",
"contentLength": 1057,
"lastModified": "2020-02-07T16:50:16.133-05:00",
"remoteFileName": null,
"dataPath": "preprd/datalake/lake/nes/negotiation/execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=3/version=1",
"version": 1,
"source": "NETS",
"numberOfRecords": -1,
"transferStatus": "REPORT_CREATED",
"creationDate": "2020-02-07"
},
]
I would like to get something like this:
[{
"adlsFullPath": "part-00000-1399b2e0-5fa5-484b-91f1-9dec0601b885-c000.csv.gz",
"contentLength": 20,
"lastModified": "2020-02-07T16:50:16.132-05:00",
"remoteFileName": null,
"numberOfRecords": -1,
"transferStatus": "REPORT_CREATED",
"creationDate": "2020-02-07",
"batches":{
{ "dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=3/version=1",
"version": 1,
"source": "NETS",
},
{ "dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=2/version=1",
"version": 1,
"source": "NETS",
},
{ "dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=1/version=1",
"version": 1,
"source": "NETS",
}
},
{
"adlsFullPath": "part-00007-1399b2e0-5fa5-484b-91f1-9dec0601b885-c000.csv.gz",
"contentLength": 1104,
"lastModified": "2020-02-07T16:50:16.133-05:00",
"remoteFileName": null,
"numberOfRecords": -1,
"transferStatus": "REPORT_CREATED",
"creationDate": "2020-02-07",
"batches":{
{ "dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=3/version=1",
"version": 1,
"source": "NETS",
},
{ "dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=2/version=1",
"version": 1,
"source": "NETS",
},
{ "dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=1/version=1",
"version": 1,
"source": "NETS",
}
},
{
"part-00015-1399b2e0-5fa5-484b-91f1-9dec0601b885-c000.csv.gz",
"contentLength": 1104,
"lastModified": "2020-02-07T16:50:16.133-05:00",
"remoteFileName": null,
"numberOfRecords": -1,
"transferStatus": "REPORT_CREATED",
"creationDate": "2020-02-07",
"batches":{
{ "dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=3/version=1",
"version": 1,
"source": "NETS",
},
{ "dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=2/version=1",
"version": 1,
"source": "NETS",
},
{ "dataPath": "execution_v1/integration_date=2020-02-07/business_date=2020-02-07/batch_id=1/version=1",
"version": 1,
"source": "NETS",
}
}
}]

Answer 1

Since groupBy returns a Map not a List, you get an error when you do
return reportBatchesList.groupBy({it.adlsFullPath}, {it})
From a function having return type List<ReportWithBatches>. So you will have to change the return type of your function to Map<String, ReportWithBatches> in service.
In your case groupBy will give you a Map which will look something as following
{adlsFullPath1=[Report1, Report2], adlsFullPath2=[Report3]}
For more information read the docs.