val studentContainer = FC("StudentsContainer") { _: Props ->
    val queryClient = useQueryClient()

    val studentListQueryKey = arrayOf("studentList")
        .unsafeCast<QueryKey>()

    val query = useQuery<String, QueryError, String, QueryKey>(
        queryKey = studentListQueryKey,
        queryFn = {
            fetchText(Config.studentsPath)
        }
    )

val addStudentMutation = 
    useMutation<HTTPResult, Any, Student, Any>(
    mutationFn = { student: Student -> 
        fetch( 
            Config.studentsPath,
            jso { method = "POST"
                headers = json(
                    "Content-Type" to "application/json")
                body = Json.encodeToString(student) } ) },
    options = jso {
        onSuccess = { _: Any, _: Any, _: Any? ->
            queryClient.invalidateQueries<Any>(studentListQueryKey)
        } } )

val deleteStudentMutation = 
    useMutation<HTTPResult, Any, ItemId, Any>(
    mutationFn = { studentId: ItemId ->
        fetch(
            "${Config.studentsPath}$studentId",
            jso { method = "DELETE" }
        )
    },
    options = jso {
        onSuccess = { _: Any, _: Any, _: Any? ->
            queryClient.invalidateQueries<Any>(studentListQueryKey)
        }
    }
)

val updateStudentMutation = 
    useMutation<HTTPResult, Any, Item<Student>, Any>(
    mutationFn = { studentItem: Item<Student> ->
        fetch(
            "${Config.studentsPath}${studentItem.id}",
            jso {
                method = "PUT"
                headers = json(
                    "Content-Type" to "application/json")
                body = Json.encodeToString(studentItem.elem) } ) },
    options = jso {
        onSuccess = { _: Any, _: Any, _: Any? ->
            queryClient.invalidateQueries<Any>(studentListQueryKey)
        } } )

val items =
    Json.decodeFromString<Array<Item<Student>>>(query.data ?: "")
CAddStudent {
    addStudent = { it: Student ->
        addStudentMutation.mutateAsync(it, null)
    } }
CStudentList {
    students = items
    deleteStudent = {  it: ItemId ->
        deleteStudentMutation.mutateAsync(it, null)
    }
    updateStudent = { it: Item<Student> ->
        updateStudentMutation.mutateAsync(it, null)
    } }