How to pass a variable from Shiny app to R Markdown? - r

Question

In my toy example, I am trying to render Rmd file in the shiny app while passing a variable from Shiny to Rmd. Somehow, the Rmd file is not able to pick the input input$selectInput passed to Rmd file. Can someone show me how to pass a variable from Shiny to Rmd file and print it there?
My intent is to use Rmd file as a template which will be filled by variables from Shiny App at runtime. There may be better alternatives to this approach to render HTML templates in Shiny, do let me know if you know any better approches.
library(shiny)
library(shinydashboard)
library(knitr)
sidebar <- dashboardSidebar(
collapsed = FALSE,
sidebarMenu(
id = "menu_sidebar",
conditionalPanel(
condition = "input.main_tab == 'tab 1'",
selectizeInput(inputId = "selectInput", label = "Choose an option", choices = c("a", "b", "c"), selected = "a", multiple = FALSE),
radioButtons(inputId = "buttons", label = "Choose one:",
choices=c(
"A" = "a",
"B" = "b"))
)
)
)
body <- dashboardBody(
fluidRow(
tabsetPanel(
id = "main_tab",
selected = "tab 1",
tabPanel(title = "tab 1", "Tab content 1",
conditionalPanel("input.buttons == 'a'",
{
knit("text1.Rmd", envir = globalenv(), quiet = T)
withMathJax(includeMarkdown("text1.md"))
},
tags$style("html, body {overflow: visible !important;")),
conditionalPanel("input.buttons == 'b'", htmlOutput("plot_overview_handler"))
)
)
)
)
shinyApp(
ui = dashboardPage(
dashboardHeader(title = "tabBoxes"),
sidebar,
body
),
server = function(input, output) {
output$tabset1Selected <- output$tabset2Selected <- renderText({
input$main_tab
})
output$plot_overview_handler <- renderUI({
pars <- list(variable_1 = input$selectInput)
includeMarkdown(rmarkdown::render(input = "text2.Rmd",
output_format = "html_document",
params = pars,
run_pandoc = FALSE,
quiet = TRUE,
envir = new.env(parent = globalenv())))
})
}
)
Rmd File 1 - text1.Rmd
---
title: "tst2"
output: html_document
runtime: shiny
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
#``` # Uncomment this to run code
## R Markdown
```{r cars}
print(input$selectInput)
#``` # Uncomment this to run code
Rmd File 2 - text2.Rmd
---
title: "tst2"
output: html_document
runtime: shiny
params:
variable_1: NA
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
#``` # Uncomment this to run code
## R Markdown
```{r cars}
print(params$variable_1)
#``` # Uncomment this to run code