I would like to use column names that where selected by user in flextable

I would like to have the grouped columns bold. But the function bold doesnt accept a string type of column name. How can I make input[[paste0("options_agg_", input$tabs)]] work for selecting rows in bold function?

This works:

ft <- as_grouped_data(filtered_other(), groups = input[[paste0("options_agg_", input$tabs)]], columns = input[[paste0("options_dim_", input$tabs)]]) %>%
      as_flextable() %>%
      bold(i = ~ !is.na(Product.category))
    
    htmltools_value(ft)

and this does not:

ft <- as_grouped_data(filtered_other(), groups = input[[paste0("options_agg_", input$tabs)]], columns = input[[paste0("options_dim_", input$tabs)]]) %>%
      as_flextable() %>%
      bold(i = ~ !is.na(input[[paste0("options_agg_", input$tabs)]]))
    
    htmltools_value(ft)

I don't want it to be always set to Product.category.

I have tried: as.formula. I have also considered eval & parse. But I did not make it work

One option would be to use reformulate to create your formula object.

Using a minimal reproducible example based on mtcars:

library(flextable)
library(magrittr)

col <- "mpg"

fml <- reformulate(paste0("!is.na(", col, ")"))

fml
#> ~!is.na(mpg)

ft <- as_grouped_data(mtcars, groups = "cyl", columns = c("cyl", "mpg")) %>%
  as_flextable() %>%
  bold(i = fml)

ft