Update column in R datatable based on inputs in Shiny - r

Question

I am trying to append the user input to the output table in Shiny app. And when the user changes any values for Total Cost it should update in the table before I click on run. How can I fix that?
library(dplyr)
library(shiny)
shinyApp(
ui = basicPage(
mainPanel(
numericInput("model_input", label = h5("Total Cost"), value = 10000),
numericInput("iterations", label = h5("Runs"), value = 900),
actionButton("run", "Run"),
actionButton("reset", "reset"),
tableOutput("view")
)
),
server = function(input, output) {
v <- reactiveValues(data = mtcars %>% mutate(budget = input$model_input)) # this makes sure that on load, your default data will show up
observeEvent(input$run, {
v$data <- mtcars %>% mutate(new = mpg * input$model_input +input$iterations)
})
observeEvent(input$reset, {
v$data <- mtcars # your default data
})
output$view <- renderTable({
v$data
})
}
)

Answer 1

You cant use input$model_input outside a reactive context. That was probably causing some issues. We simple move it outside into an observeEvent.
library(dplyr)
library(shiny)
shinyApp(
ui = basicPage(
mainPanel(
numericInput("model_input", label = h5("Total Cost"), value = 10000),
numericInput("iterations", label = h5("Runs"), value = 900),
actionButton("run", "Run"),
actionButton("reset", "reset"),
tableOutput("view")
)
),
server = function(input, output) {
v <- reactiveValues(data = mtcars) # this makes sure that on load, your default data will show up
observeEvent(input$model_input,{
v$data <- v$data %>% mutate(budget = input$model_input)
})
observeEvent(input$run, {
v$data <- mtcars %>% mutate(new = mpg * input$model_input +input$iterations)
})
observeEvent(input$reset, {
v$data <- mtcars # your default data
})
output$view <- renderTable({
v$data
})
}
)