Render Markdown into email

Source: R/render.R

Render either Plain Markdown or R Markdown directly into the body of an email.

If input is a file then it will be interpreted as R Markdown it its extension is either "Rmd" or "Rmarkdown". Otherwise it will be processed as Plain Markdown.

render(
  msg,
  input,
  params = NULL,
  squish = TRUE,
  css_files = c(),
  include_css = c("rmd", "bootstrap"),
  language = FALSE,
  interpolate = TRUE,
  .open = "{{",
  .close = "}}",
  .envir = NULL
)

Arguments

msg

A message object.

input

The input Markdown file to be rendered or a character vector of Markdown text.

params

A list of named parameters that override custom parameters specified in the YAML front-matter.

squish

Whether to clean up whitespace in rendered document.

css_files

Extra CSS files.

include_css

Whether to include rendered CSS from various sources ("rmd" — native R Markdown CSS; "bootstrap" — Bootstrap CSS).

language

Language of content. If FALSE then will not include language field. If TRUE then will attempt to auto-detect language. Otherwise will use the specified language.

interpolate

Whether or not to interpolate into input using glue.

.open

The opening delimiter.

.close

The closing delimiter.

.envir

Environment used for glue interpolation. Defaults to parent.frame().

Value

A message object.

Plain Markdown

Plain Markdown is processed with commonmark::markdown_html().

R Markdown

R Markdown is processed with rmarkdown::render().

Regardless of what output type is specified in the input file, render() will always use the "html_document" output format.

Rending an R Markdown document can result in a lot of CSS. When all of the CSS is included in the HTML <head> and sent to GMail it can result in a message which is not correctly displayed inline in the Gmail web client. To get around this you can specify include_css = FALSE. This will mean that some styling will not be present in the resulting message, but that the message content will be correctly rendered inline.

See also

text, html

Examples


# Plain Markdown

markdown <- "[This](https://www.google.com) is a link."
filename <- "message.md"

# Render from Markdown in character vector.
msg <- envelope() %>% render(markdown)

# Create a file containing Markdown
cat(markdown, file = filename)

# Render from Markdown in file.
msg <- envelope() %>% render(filename)

# Cleanup.
file.remove(filename)
#> [1] TRUE

# R Markdown

filename <- "gh-doc.Rmd"

# Create an Rmd document from template.
rmarkdown::draft(
  filename,
  template = "github_document",
  package = "rmarkdown",
  edit = FALSE
)

# Check for suitable version of Pandoc (https://pandoc.org/).
#
# Need to have version 2.0 or greater to support required --quiet option.
#
pandoc <- rmarkdown::find_pandoc()
suitable_pandoc <- !is.null(pandoc$dir) && grepl("^2", pandoc$version)

# Render from Rmd file.
if (suitable_pandoc) {
  msg <- envelope() %>%
    render(filename, include_css = c("rmd", "bootstrap"))
}

# Cleanup.
file.remove(filename)
#> [1] TRUE