dynamic - R Shiny : Observe only works once -

i developing r shiny dashboard school project have problem reactive values , observers. want update ui (and more precisely selectinput) when user succesfully logged in.

here current code

global.r

db <<- dbconnect(sqlite(), dbname = "ahp_data.db") isconnected <<- 0  #imagine here df contain model names df <- data.frame(option1 =c("no model selected),                  option2 =c("model_1","model_2")      )  reactvalues <<- reactivevalues() isconnectvar <- null 

ui.r

library(shinydashboard)  dashboardpage(    dashboardheader(),   dashboardsidebar(),   dashboardbody(  #authentification panel sidebarlayout(   sidebarpanel(         titlepanel("authentification"),         textinput('username', label="user name"),         passwordinput('password', label= "password"),         actionbutton("connectbutton", label='connect'),         actionbutton("subscribebutton",label='subscribe'),         actionbutton("logoutbutton", label="log out")    ),   sidebarpanel(         #input update when logged in         selectinput("selectmodelinput", label="model   selection",choices=list("no model selected")),         actionbutton("newmodelbutton",label="new model"),         actionbutton("renamemodelbutton", label="rename model"),         actionbutton("duplicatemodelbutton",label="duplicate model"),         actionbutton("loadmodelbutton", label='load model'),         actionbutton("deletemodelbutton", label='delete model')   )  ) 

server.r

connect <- function(username,pwd){   isconnected <<- 0;   qry = paste0("select password user pseudo = \'",username,"\'")   res= dbgetquery(db,qry )   res = paste0(res)   if(res==pwd)   {     isconnected <<- 1;     print("connected")    }   else{     print("unable connect database")   }  function(input, output, session) {   isconnectedvar <- reactive({     isconnected+1   })    #authentification panel dynamic ui   observe({     if(isconnected== 0){      reactvalues$selector <<- updateselectinput(session,"selectmodelinput", label="model selection", choices = as.character(df[[paste0(option,isconnectedvar())]]))     }     else{       reactvalues$selector <<- updateselectinput(session,"selectmodelinput",  label="model selection", choices = as.character(df[[paste0(option,isconnectedvar())]]))     }   })   observeevent(input$connectbutton, {     username= paste0(input$username)     userpwd = paste0(input$password)     connect(user = username,pwd = userpwd)   }) 

i've tried several tutorials on internet, using reactive, observe etc can't figure out what's wrong code, me guys.

thanks in advance alexi

your want code react value of isconnected. suggest let variable local - not global - there possibility mark reactive value via makereactivebinding

here suggestion (in one-file app):

library(shiny) library(shinydashboard)  df <- data.frame(option1 =c("no model selected"),                  option2 =c("model_1","model_2") )  runapp(   shinyapp(     ui = shinyui(       dashboardpage(         dashboardheader(),         dashboardsidebar(),         dashboardbody(          #authentification panel         sidebarlayout(           sidebarpanel(             titlepanel("authentification"),             textinput('username', label="user name"),             passwordinput('password', label= "password"),             actionbutton("connectbutton", label='connect'),             actionbutton("subscribebutton",label='subscribe'),             actionbutton("logoutbutton", label="log out")           ),           sidebarpanel(             #input update when logged in             selectinput("selectmodelinput", label="model   selection",choices=list("no model selected")),             actionbutton("newmodelbutton",label="new model"),             actionbutton("renamemodelbutton", label="rename model"),             actionbutton("duplicatemodelbutton",label="duplicate model"),             actionbutton("loadmodelbutton", label='load model'),             actionbutton("deletemodelbutton", label='delete model')           )         )       )       )     ),      server = function(input, output, session) {        # function inside such has scope of server       connect <- function(username,pwd){         isconnected <<- 0;         qry = paste0("select password user pseudo = \'",username,"\'")         res= "12345"         res = paste0(res)         if(res==pwd)         {           isconnected <<- 1;           print("connected")          }         else{           print("unable connect database")         }       }        # set per-instance variable , make reactive       isconnected <- 0       makereactivebinding("isconnected")        # fires whenever isconnected changes       isconnectedvar <- reactive({         isconnected+1       })        #authentification panel dynamic ui       observe({         if(isconnected== 0){           updateselectinput(session,"selectmodelinput", label="model selection", choices = as.character(df[[paste0("option",isconnectedvar())]]))         }         else{           updateselectinput(session,"selectmodelinput",  label="model selection", choices = as.character(df[[paste0("option",isconnectedvar())]]))         }       })        observeevent(input$connectbutton, {         username= paste0(input$username)         userpwd = paste0(input$password)         connect(user = username,pwd = userpwd)       })     }   ) ) 

note: edited call df since not correct in code sample.