pass the read data in server.R into ui.R using shiny

Question

In ui.R, I read at first a fixed sample data

datT2<-fread(paste0('./data/','30062019KRB.csv'),header=TRUE, sep=";",stringsAsFactors = FALSE , encoding="UTF-8")

to extract the data structure. however there are many data like 30062019KRB.csv whose structure varies a little bit from each other.

In the next step in ui, I choose one name or one file and pass it to server.R

ui.R:

 selectInput(inputId = 'date',
          label = 'Stichtag:',
          choices = list.files('./data', full.names = FALSE,
                   recursive = FALSE)),

and in server.R:

I load the data based on the file name (for instance: 30062018KRB.csv)

  data <- reactive({
    infile <- input$date
    if (is.null(infile)){
      return(NULL)
    }
    daS<-fread(paste0('./data/',infile),header=TRUE, sep=";")
    daS[is.na(data)]<- 0
    daS
  })

Now my question is: How can I pass the output of data <- reactive({ ... to ui.R in other words I want to set datT2 in ui.R as output of data <- reactive({ ....

I tried in server:

  output$datainput <- DT::renderDataTable({ 
    datein<-data ()
    })

and ui.R

datT2<-DT::dataTableOutput("datainput ")

BUT it does not work. Goal: To use the structure of the data within ui.R which user selected in ui.R. Any idea how can I pass the read data in server to ui.R?

I tried even in ui.R

datT2<-uiOutput("datainput ")

and got the following error:

Warning: Error in :=: Check that is.data.table(DT) == TRUE. Otherwise, := and `:=`(...) are defined for use in j, once only and in particular ways. See help(":=").
  48: stop
  47: :=

I want just to read the data in ui.R dynamically. Something like:

     selectInput(inputId = 'date',
              label = 'Stichtag:',
              choices = list.files('./data', full.names = FALSE,
                       recursive = FALSE)),
...
datT2<-fread(paste0('./data/',input$date),header=TRUE, sep=";",stringsAsFactors = FALSE , encoding="UTF-8")

I need something like sing JavaScript objects within ui.R