how do I group by "group" when located in the sub model?
i tried do this, but it error result
mtop.groupBy { it.sub[0].group }
this my code
// my model
data class mTop(val kategori : String, val sub : ArrayList<mSub>)
data class mSub(val id_menu : String, val nama_menu : String, val gambar : String, val group : String)
// my activity
val mtop: ArrayList<mTop> = ArrayList()
val msub: ArrayList<mSub> = ArrayList()
mtop.add(mTop(header, msub))
sorry I often ask on this forum but never helped others, because I'm a beginner and my English is bad. Thank You
mtop.groupBy { it.sub[0].group }
The error you are getting is because sub is empty and you are trying to get the first element.
What you can probably do is to do a filter before trying to groupBy:
mtop.filter{it.sub.isNotEmpty()}.groupBy{it.sub[0].group}
Related
My objective is to collect distinct values of select fields to provided them as filter options for the frontend. DistinctValuesCollector seems to be the tool for this, however since I haven't found code sample and documentation except for the Javadocs I can't currently correctly construct this collector. Can anyone provide an example?
This is my attempt which doesn't deliver the desired distinct values of the field PROJEKTSTATUS.name.
val groupSelector = TermGroupSelector(PROJEKTSTATUS.name)
val searchGroup = SearchGroup<BytesRef>()
val valueSelector = TermGroupSelector(PROJEKTSTATUS.name)
val groups = mutableListOf(searchGroup)
val distinctValuesCollector = DistinctValuesCollector(groupSelector, groups, valueSelector)
That field is indexed as follows:
document.add(TextField(PROJEKTSTATUS.name, aggregat.projektstatus, YES))
document.add(SortedDocValuesField(PROJEKTSTATUS.name, BytesRef(aggregat.projektstatus)))
Thanks to #andrewJames's hint to a test class I could figure it out:
fun IndexSearcher.collectFilterOptions(query: Query, field: String, topNGroups: Int = 128, mapper: Function<String?, String?> = Function { it }): Set<String?> {
val firstPassGroupingCollector = FirstPassGroupingCollector(TermGroupSelector(field), Sort(), topNGroups)
search(query, firstPassGroupingCollector)
val topGroups = firstPassGroupingCollector.getTopGroups(0)
val groupSelector = firstPassGroupingCollector.groupSelector
val distinctValuesCollector = DistinctValuesCollector(groupSelector, topGroups, groupSelector)
search(query, distinctValuesCollector)
return distinctValuesCollector.groups.map { mapper.apply(it.groupValue.utf8ToString()) }.toSet()
}
in my application ,apart from the primarykey of a user ,I will still need to generate a unique ID(12 -15 charactors) for showing to the public .
I am new with Room ,Could you please take a look my code ?
Thank you so much in advance !
#Entity
data class UserInfo(
#PrimaryKey(autoGenerate = true)
val userId:Int = 0,
val image: String,
val imageSource : String,//Local or Online
val username : String,
val gender :String,
val userPublicId:String, //this is the id that need to generate 12-15
val birthday : String,
val userIntro :String,
)
As mentioned #Tenfour04 you can use some ways to generate random string. I think org.apache.commons.lang3.RandomStringUtils is a good choice. For exmaple look at the following methods: randomAscii, randomAlphabetic, randomAlphanumeric.
I have a data class I want to populate, where in one constructor I have the data already, and in another I would like to fetch it only when it is required, which is rare.
A sample code would be:
data class Source1(val str1: String)
data class Source2(val str2: String)
data class DTO(val data1: String, val data2: String) {
// ctor which does not need laziness
constructor(source1: Source1) : this(
data1 = source1.str1,
data2 = source1.str1
)
// ctor which needs costly data
constructor(source2: Source2, costlyData: String) : this(
data1 = source2.str2,
data2 = costlyData
)
}
fun demo() {
val source1 = Source1("some str - 1")
DTO(source1)
val source2 = Source2("some str - 2")
val costlyData: String = costlyOperation() // this is the operation I'd like to execute lazily
DTO(source2, costlyData)
}
I'd say the easiest way would be to accept a function as a constructor parameter, something like this:
class DTO(provider:()->String){
constructor(data: String):this({data})
val data by lazy{ provider()}
}
So you can use it in both ways:
val eager = DTO("some str - 1")
val lazy = DTO(::costlyOperation)
A bit nicer way is to have a Source abstraction with different implementations for providing a constant value and performing an operation. But the overall idea would be the same.
Although I wouldn't call this DTO anymore and it loses its data class capabilities regarding the content.
When trying to 'add' a custom object to an ArrayList, the ArrayList remains null
I've tried modifying the data class initialization by using MutableLists, among other things
Here is the data class that I'm using:
data class WYRStatistics(val team: String, val league: String, val gp: String, val g: String, val a: String, val pt: String, val pim: String, val pm: String)
This is where I'm using the data class to construct on object and try to add the object to an ArrayList
var n = 0
var statsArr: ArrayList<WYRStatistics>? = null
while (n < tempStats.length()) {
val statObject = tempStats.getJSONObject(n)
val singleStat = WYRStatistics(statObject.getString("Team"),
statObject.getString("League"),
statObject.getString("GamesPlayed"),
statObject.getString("Goals"),
statObject.getString("Assists"),
statObject.getString("Points"),
statObject.getString("PenaltyMinutes"),
statObject.getString("PlusMinus")
)
println(singleStat)
statsArr?.add(singleStat)
println(statsArr)
tempPlayer.stats?.add(singleStat)
println(tempPlayer)
n++
}
The utilization is inside of a function that handles the asynchronous task of decoding JSON. This is all working fine.
tempStats is a JSONArray - when printed it is formatted properly
When I println singleStat, the object is printed properly
However, when I 'add' singleStat to statsArr, the statsArr returns null
You are initializing arrayList to nullas what JB mentioned.
The correct way should be
val statsArr = arrayListOf<WYRStatistics>()
I parsed a json string to the following object structure using gson:
data class Base (
val expand: String,
val startAt: Long,
val maxResults: Long,
val total: Long,
val issues: List<Issue>
)
data class Issue (
val expand: String,
val id: String,
val self: String,
val key: String,
val fields: Fields
)
data class Fields (
val summary: String,
val issuetype: Issuetype,
val customfield10006: Long? = null,
val created: String,
val customfield11201: String? = null,
val status: Status,
val customfield10002: Customfield10002? = null,
val customfield10003: String? = null
)
Everything works fine and also the object model is correct, because I can access each element of the object.
However, I encountered the problem that I dont know how to get a list of all field-elements. Right now, I have only figured out how to access one item (by using an index and get()-function):
val baseObject = gson.fromJson(response, Base::class.java)
val fieldsList = baseObject.issues.get(0).fields
I actually want to have a list of all field elements and not just one. Is there a gson function allowing me to do that? I couldn't find anything about it in the gson documentation for java.
You don't have to look for some gson function when you've already created a baseObject. You just need to get from each issue it's fields and you can use a map function to achieve this, it will convert each issue to a new type so you can get issue fields there
val fieldFromAllIssues: List<Fields> = baseObject.issues.map { it.fields }
it in this context is a one issue. More explanation about it is here