将 rmarkdown 渲染为字符变量

Question

I am fairly new to R markdown. I have built an app that requires the user to provide multiple inputs to generate a table, which can then be saved locally. I have been now asked to implement a sort of report to list all the variables inserted by the user (in a sort of formatted document), so that before generating the table one can review all the settings and change them in case of errors.

To avoid major UI restructure, I thought about using ar markdown document and visualize it inside a modal. My problem is that rmarkdown::render renders to an output, while bs_modal takes for the argument body a character (HTML) variable. Is there a way to make this work? Or are there better way to accomplish this?

A minimal example:

my .Rmd

---
title: "Dynamic report"
output:
  html_document: default
  pdf_document: default
params:
  n : NA
---

A plot of `r params$n` random points.

```{r, echo=FALSE}
plot(rnorm(params$n), rnorm(params$n))
```

My App.R

library(shiny)
library(bsplus)
library(rmarkdown)

shinyApp(
  ui = fluidPage(
    selectInput(
      inputId = "numb",
      label = "Label with modal help",
      choices = 50:100
    ),
    actionButton(inputId = "mysheet",
                 label = "Open modal") %>%  bs_attach_modal(id_modal = "modal1"),
    textOutput("result")
  ),
  server = function(input, output) {
    observeEvent(input$mysheet, {
      params <- input$numb
      md_out <-
        rmarkdown::render(
          "report.Rmd",
          params = params,
          envir = new.env(parent = globalenv())
        )
      bs_modal(
        id = "modal1",
        title = "Equations",
        body = md_out,
        size = "medium"
      )
      
    })
    output$result <- renderText({
      paste("You chose:", input$numb)
    })
  }
)

Answer 1

bs_modal does not work like this, it must be in the UI. Below is a solution using the classical Shiny modal, no bsplus or other package.

library(shiny)

shinyApp(
  ui = fluidPage(
    selectInput(
      inputId = "numb",
      label = "Label with modal help",
      choices = 50:100
    ),
    actionButton(inputId = "mysheet",
                 label = "Open modal"),
    textOutput("result")
  ),
  server = function(input, output) {
    observeEvent(input$mysheet, {
      params <- list(n = input$numb)
      md_out <-
        rmarkdown::render(
          "report.Rmd",
          params = params,
          envir = new.env(parent = globalenv())
        )
      showModal(modalDialog(
        includeHTML(md_out),
        title = "Equations",
        size = "m"
      ))
      
    })
    output$result <- renderText({
      paste("You chose:", input$numb)
    })
  }
)

Use html_fragment as the Rmd output:

---
title: "Dynamic report"
output:
  html_fragment
params:
  n : NA
---

A plot of `r params$n` random points.

```{r, echo=FALSE}
plot(rnorm(params$n), rnorm(params$n))
```