R shiny ui object order of display - r

Question

I'm building a simple shiny app which will take inputs from the user and fetch data from a table in the DB and take the number of records to be downloaded as an input and provide a download file option.
Everything below works just fine. My only concern is the textInput bar( variable : uiOutput("text") in the ui and output$text in the server) appears only after the datatableOutput is displayed. I do not understand why this happens.
Ideally, I want the textInput bar ('uiOutput("text")') object to be displayed once the leaf(i.e. input$leaf1 is not null) is selected and then I want the datatableOutput to be displayed and then the Download Button should come up.
Is there a way I can achieve this? Thanks
library(shiny)
library(shinydashboard)
#library(stringr)
library(DT)
#library(shinyBS)
ui <- dashboardPage(
dashboardHeader(title = strong("DASHBOARD"),titleWidth = 240),
dashboardSidebar(
sidebarMenu(
selectizeInput("x", "Choose a number:", choices = sort(unique(lftable$x)), multiple = TRUE),
uiOutput("leaf_categ")
)
),
dashboardBody(
fluidRow(
uiOutput("text"),
dataTableOutput("lm_df"),
downloadButton('downloadData', 'Download')
)))
server <- function(input, output){
output$leaf_categ <- renderUI(
selectizeInput("leaf1", "Choose leaf categories:",
choices = reactive(unique(lftable[lftable$num %in% input$x, c("X_NAME")]))(),
multiple = TRUE)
)
#### creates a text input box
#### number of records to be downloaded is provided as input
output$text <- renderUI({
if(is.null(reactive(input$leaf1)())){
return()
}else{
textInput("var1", label = "Enter the number of records to be downloaded", value = "")
}
})
#### fetches data from DB
lm <- reactive({
if(is.null(input$leaf1)){
return()
}else{
leaf_id <- unique(lftable[lftable$X_NAME %in% input$leaf1, c("leaf_id")])
query_str <- paste('select * from table1 where current_date between start_dt and end_dt and score_num >= 0.1 and x in (' , input$x, ')', ' and X_ID in (', leaf_id, ')', ';', sep = "")
}
lm_data <- getDataFrmDW(query_str)
})
###creates a download tab
output$downloadData <- downloadHandler(
filename = function() { paste("lm_user_data", '.csv', sep='') },
content = function(file) {
lm_df <- lm()
lm_df <- lm_df[1:(as.integer(input$text)),]
print(dim(lm_df))
write.csv(lm_df, file, row.names = F)
})
output$lm_df <- DT::renderDataTable(lm())
}
shinyApp(ui, server)