Shiny how to refresh data loaded before server function - r

Question

I need to develope a shiny interface with many csv loaded in it. Based on my past experience with shiny, I prefer to import this data before the server function, in this way I hope that each session will run faster. The app will be restarted each morning, so data will be daily refreshed.
The problem is that I need to consider an extra refresh during the day, performed manualy with a button that source an external updating script.
I can't (but I hope that is possibele), refresh the data loaded at the start of the app. Below my (dummy) code:
server:
library(shinydashboard)
library(plotly)
library(data.table)
library(dplyr)
path1<-"C:/Users/.../DATA/"
path2<-"C:/Users/../DATA/csv/"
##load dataset at first start
table<-fread(file=paste0(path2,"main.csv"),data.table=FALSE))
shinyServer(function(input, output,session) {
##### refresh data with button####
observeEvent(input$refresh_data,{
source(paste0(path1,"any_script.r"),local = FALSE)
table<<-fread(file=paste0(path2,"main.csv"))
})
#####...ui####
table_r<-reactive({
##obs populate the input for choosing rows to be plotted
obs<-rev(unique(table$anycolumn))
curve_sint<-list(
lotti=obs,
data=obs
)
})
output$obs_ui<-renderUI({
selectInput("input_obs","Please choose the batch:",
choices =table()$obs ,multiple = T)
})
output$plot<-renderPlotly({
table_r()$data%>%
filter(anycolumn==input$input_obs)%>%
plot_ly(
x=~x,
y=~y,
color=~anycolumn,
type="scatter"
)
})
})
ui:
library(shinydashboard)
ui <- dashboardPage(
dashboardHeader(
title = "shiny"
),
dashboardSidebar(
width=250,
sidebarMenu(
menuItem(
"plot data"
tabName = "clhc",
icon = NULL
),
menuItem(
"Update data",
icon=icon("gear"),
tabName="update_data"
)
)
),
dashboardBody(
tabItems(
tabItem(
tabName = "clhc",
fluidRow(
column(width=3,
uiOutput("obs_ui")
),
),
fluidRow(
column(
width=12,
fluidRow(
plotlyOutput("plot")
)
)
)
),
tabItem(
tabName = "update_data",
fluidRow(
box(
width=12,
title="Sint HC",
actionButton("refresh_sint_hc","Refresh", icon=icon("refresh"))
)
)
)
)
)
)
I'm sure that the script inside observeevent works fine, because if I put a print(nrow(table)) after the fread I can see that table is correctly refreshed. I can't understand where the new data is stored because from the plot panel is stil available the old data before the update.
Is my attempt completley wrong?

Answer 1

Using <<- will make table accessible globally, and after terminating your shiny app, but you need it to be reactive. Here is a brief example on using a reactiveVal (setting to table1 as default) that gets modified when the actionButton is selected and a new data file is read.
library(shiny)
library(data.table)
table1 <- fread(file = 'atest1.csv')
ui <- fluidPage(
verbatimTextOutput("text"),
actionButton("refresh", "Refresh")
)
server <- function(input, output, session) {
rv <- reactiveVal(table1)
output$text <- renderText({
names(rv())
})
observeEvent(input$refresh, {
print("Refresh")
table1 <<- fread(file = 'atest2.csv')
rv(table1)
})
}
shinyApp(ui, server)