shiny R can't display a text from vector - r

Question

How can I display value only on the browser?
Below is my code.
ui <- shinyUI(bootstrapPage(
absolutePanel(
textOutput("renderText1")
)
)
)
server <- function(input,output,session)
{
observeEvent(input$dropdown, {
query <- sprintf("select ....",input$dropdown)
cabinet_info <- dbGetQuery(con,query)
output$renderText1 <- renderText({
paste(cabinet_info)
})
})
}
Below are the outputs:
c('a','w','r','t')

Answer 1

While Geovany's answer may work, it is not a good practice to use observeEvent with the global assignment operator (<<-).
If you would like to execute a side effect (e.g. writing a file, plotting, printing), then you can use observe or observeEvent, but if you want to use a return value, use eventReactive instead.
ui <- shinyUI(bootstrapPage(
absolutePanel(
selectInput("dropdown", label = 'SelectInput', choices = c('A', 'B')),
textOutput("renderText1")
)
)
)
server <- function(input,output,session)
{
cab <- eventReactive(input$dropdown, {
query <- sprintf("select ....",input$dropdown)
#cabinet_info <- dbGetQuery(con,query) #Replaced by a constant
cabinet_info <- paste(c(input$dropdown, 'a','w','r','t'), sep=",")
})
output$renderText1 <- renderText({
cab()
})
}
shinyApp(ui, server)
Call eventReactive from the server side just like a function: cab()

Answer 2

This could help you
runApp(list(
ui = shinyUI(bootstrapPage(
absolutePanel(
actionButton("dropdown", "dropdown"),
textOutput("renderText1")
)
)
),
server = shinyServer(function(input, output) {
cabinet_info <- NULL
observeEvent(input$dropdown, {
cabinet_info <<- c('a','w','r','t')
})
output$renderText1 <- renderText({
input$dropdown
paste(cabinet_info, collapse = ',')
})
})
))