r shiny observe function clears text input - r

Question

Hi I am trying to build a login page that contacts an API service and validates user credentials. If the credentials are correct then a new user interface appears and simply makes a plot. If it is not correct a message at the login screen should say "incorrect login". Currently, when I try to type in either of the fields at the login page (ui1.r) the field refreshes/wipes itself after a second or so, thus preventing me from passing on user input to the API. I have the following files
server.r:
rm(list = ls())
library(shiny)
library(dplyr)
library(shinyjs)
umls <- dbConnect(drv=RSQLite::SQLite(),
dbname="/media/sf_umls-2018AA-full/2018AA-full/2018AA/META/umls_browser.sqlite3")
licenseCode <- "mylicense"
shinyServer(function(input, output) {
source('ui1.R') #login page
output$page <- renderUI({ ui1 })
observe({
z<-system(paste("perl", "/media/sf_umls-2018AA-full/2018AA-full/2018AA/META/umls_auth.pl",
input$user, input$password),intern=TRUE)
if (grepl("false",z[22])) {
renderText("incorrect login")
}
if (grepl("true",z[22]))
{
output$page <- renderUI({ ui2 })
output$table <- renderTable({mtcars()})
}
})
})
ui1.r
ui1 <- shinyUI(fluidPage(
# Application title
titlePanel("UMLS Constraint Browser"),
# Sidebar with a slider input for number of bins
sidebarLayout(
sidebarPanel(
textInput("user", "User",""),
textInput("password", "Password",""),
actionButton("login", "Login")
),
mainPanel(
tableOutput("table")
)
)
))
What appears to be the problem?

Answer 1

I think the problem comes from the observe function. Each time you write a letter, it sends a request to your credential database. You should try to use
ObserveEvent instead :
shinyServer(function(input, output) {
observeEvent(input$login, {
z<-system(paste("perl", "/media/sf_umls-2018AA-full/2018AA-full/2018AA/META/umls_auth.pl",
input$user, input$password),intern=TRUE)
if (grepl("false",z[22])) {
renderText("incorrect login")
}
if (grepl("true",z[22]))
{
output$page <- renderUI({ ui2 })
output$table <- renderTable({mtcars()})
} })
})
Here, a request is made only when the user clicks on the login button. Tell me if it works for you.