Knit with parameters in R Markdown by selecting shapefile (.shp) as file input

[Iracambi]

I posted this same question last week on Stack Exchange but did not receive any answers.

I am trying to render an R Markdown script to a PDF using Knit with parameters. I want other people to be able to render the report using a UI generated by the YAML header. I would like to use a shiny control (file) as as a parameter input instead of the generic text one (i.e. the UI opens up a window in which the user can select the file from a File Explorer).

Minimal reproducible example:

I first create a copy of the sf package's nc.shp so that I can easily find it when testing the UI:

library(sf)
sf_nc <- sf::st_read(system.file("shape/nc.shp", package = "sf"), quiet = TRUE)
sf::st_write(sf_nc, 'C:/Temp/nc_temp.shp')

Here is the R Markdown (.rdm) file

title: "Params_Test"
output: pdf_document
params:
shp_program:
input: file
label: 'NC Shapefile'
value: 'C:/Temp/nc_temp.shp'
multiple: FALSE
buttonLabel: 'browse shapefiles'

knitr::opts_chunk$set(echo = TRUE)

library(sf)
library(ggplot2)

sf_nc_temp <- sf::st_read(params$shp_program)

plot <- ggplot2::ggplot(sf_nc_temp) +
  geom_sf(aes(color = NAME)) +
  geom_sf_text(aes(label = NAME)) 
plot

The tool runs fine when I just Knit using the default (Knit drop down icon > Knit with parameters > Knit). However I get the following error message when I try to select the shapefile from the UI: Line 20 Error: Cannot open 'C:\Users\username\AppData\Local\Temp\1\Rtmp8gVT2L\file2784148636a\0.shp"; The source could be corrupt or not supported. See st_drivers() for a list of supported formats.

The comments from the Stack Overflow question suggest that the issue is that a shapefile really has multiple files (with the same name but different extension) associated with it (like a .dbf) and that it is looking for those as well. I tried allowing for multiple files to be selected and included all associated files, but this did not work either.