How do I use req() with inputs created dynamically by purrr? - r

Question

I created a dynamic form using {gt} and {purrr} combined with a function that extracts the HTML of shiny::selectizeInput.
I need to ensure that inputs created dynamically with {purrr} are available for others operations.
How can I use shiny::req() for all inputs created dynamically?
# libraries
library(shiny)
library(magrittr)
# functions
selectizeInput_gt <- function(value, inputid, ...) {
as.character(shiny::selectizeInput(paste0(value, inputid),
...)) %>%
gt::html()
}
# datasets
number_tests <- 5
df <- data.frame("test_number" = 1:number_tests)
# UI
ui <- fluidPage(gt::gt_output(outputId = "table"))
# server
server <- function(input, output, session) {
output$table <- gt::render_gt({
req(df)
df %>%
tibble::rownames_to_column() %>%
dplyr::rowwise() %>%
dplyr::mutate(
rowname = as.numeric(rowname),
selectinput_column = purrr::map(
rowname,
.f = ~ selectizeInput_gt(
.x,
"_selectinput",
label = "",
choices = c("A", "B", "C")
)
)
) %>%
gt::gt()
})
}
# runApp
shinyApp(ui, server)

Answer 1

After a lot of fiddling, I figured out a way to use purrr::walk to pass the inputs to req(). To generate the inputs, I use purrr::map.
As a small example, I use the req() to prevent an error in a simple output that uses the values of the inputs.
# libraries
library(shiny)
library(magrittr)
# functions
selectizeInput_gt <- function(value, inputid, ...) {
as.character(shiny::selectizeInput(paste0(value, inputid),
...)) %>%
gt::html()
}
# datasets
number_tests <- 5
df <- data.frame("test_number" = 1:number_tests)
# UI
ui <- fluidPage(gt::gt_output(outputId = "table"),
textOutput("selections"))
# server
server <- function(input, output, session) {
output$table <- gt::render_gt({
req(df)
df %>%
tibble::rownames_to_column() %>%
dplyr::rowwise() %>%
dplyr::mutate(
rowname = as.numeric(rowname),
selectinput_column = purrr::map(
rowname,
.f = ~ selectizeInput_gt(
.x,
"_selectinput",
label = "",
choices = c("A", "B", "C")
)
)
) %>%
gt::gt()
})
output$selections <- renderText({
purrr::walk(purrr::map(paste0(df$test_number, "_selectinput"), ~input[[.]]), req)
paste(purrr::map_chr(paste0(df$test_number, "_selectinput"), ~input[[.]]))
})
}
# runApp
shinyApp(ui, server)