Update table in R Shiny - r

Question

I am just learning R. I have a small project where a timetable is displayed and the user has the possibility to enter a subject.
My problem: I do not know how to enter a subject (for example "math") in the timetable (dataframe). As soon as the user presses the action button, the subject should be entered in the table at the position ["1", "monday"].
I tried it here by:
output$my_table <- renderDataTable(df())
df <- eventReactive(input$button, {
timetable["1", "monday"] <- input$select1
})
which unfortunately does not work. Any tips and advice on how I can enter something into a table would be greatly appreciated!
This is my Code:
library(shiny)
ui <- fluidPage(
theme = bs_theme(version = 4, bootswatch = "minty"),
titlePanel(h1("My timetable", align = "center" )),
sidebarLayout(
position = c("left"),
sidebarPanel(
width = 4,
selectInput("select1", label = h5("Event:"),
choices = c("math" , "sience", "sport") ,
selected = 1,
width = 400),
actionButton("action", label = "Add")),
mainPanel(
width = 8,
tableOutput('my_table')),
),
)
and the server:
server <- function(input, output, session) {
output$my_table = renderTable({timetable<- data.frame(monday <- c("","","","",""),
tuesday <- c("","","","",""),
wednesday <- c("","","","",""),
thursday <- c("","","","",""),
friday <- c("","","","",""))},
bordered = TRUE,
spacing = c('l'),
width = "100%",
striped = TRUE,
align = 'c',
rownames = TRUE)
output$timetable <- renderDataTable(df())
df <- eventReactive(input$action, { timetable["1","monday"] <- input$select1 })
}
shinyApp(ui, server)

Answer 1

Here is a complete working example that may be helpful.
First, I might define a separate reactiveVal to store your data.frame. This will be accessible in both your table output as well as either observeEvent or eventReactive methods.
When you reference your reactiveVal, use timetable() with parentheses at the end. When you want to replace the data.frame stored in timetable, you can do timetable(new_data_frame_here). In the observeEvent, I created a temporary tmp data.frame that can be used to edit further for convenience.
library(shiny)
library(bslib)
ui <- fluidPage(
theme = bs_theme(version = 4, bootswatch = "minty"),
titlePanel(h1("My timetable", align = "center" )),
sidebarLayout(
position = c("left"),
sidebarPanel(
width = 4,
selectInput("select1", label = h5("Event:"),
choices = c("math" , "sience", "sport") ,
selected = 1,
width = 400),
actionButton("action", label = "Add")),
mainPanel(
width = 8,
tableOutput('my_table')
)
)
)
server <- function(input, output, session) {
timetable <- reactiveVal(
data.frame(monday = c("","","","",""),
tuesday = c("","","","",""),
wednesday = c("","","","",""),
thursday = c("","","","",""),
friday = c("","","","",""))
)
output$my_table = renderTable(timetable(),
bordered = TRUE,
spacing = c('l'),
width = "100%",
striped = TRUE,
align = 'c',
rownames = TRUE)
observeEvent(input$action, {
tmp <- timetable()
tmp[1, "monday"] <- input$select1
timetable(tmp)
})
}
shinyApp(ui, server)