ambiorix (version 2.2.0)

parse_json: Parse application/json data

Description

This function parses JSON data from the request body.

Usage

parse_json(req, ...)

Value

An R object (e.g., list or data frame) parsed from the JSON data.

Named list

Arguments

req

The request object.

...

Additional parameters passed to the parser function.

Details

Overriding Default Parser

By default, parse_json() uses yyjsonr::read_json_raw() for JSON parsing. You can override this globally by setting the AMBIORIX_JSON_PARSER option:

my_json_parser <- function(body, ...) {
  txt <- rawToChar(body)
  jsonlite::fromJSON(txt, ...)
}
options(AMBIORIX_JSON_PARSER = my_json_parser)

Your custom parser MUST accept the following parameters:

1. body: Raw vector containing the JSON data.

2. ...: Additional optional parameters.

See Also

parse_multipart(), parse_form_urlencoded()

Examples

if (interactive()) {
  library(ambiorix)
  library(htmltools)
  library(readxl)

  page_links <- function() {
    Map(
      f = function(href, label) {
        tags$a(href = href, label)
      },
      c("/", "/about", "/contact"),
      c("Home", "About", "Contact")
    )
  }

  forms <- function() {
    form1 <- tags$form(
      action = "/url-form-encoded",
      method = "POST",
      enctype = "application/x-www-form-urlencoded",
      tags$h4("form-url-encoded:"),
      tags$label(`for` = "first_name", "First Name"),
      tags$input(id = "first_name", name = "first_name", value = "John"),
      tags$label(`for` = "last_name", "Last Name"),
      tags$input(id = "last_name", name = "last_name", value = "Coene"),
      tags$button(type = "submit", "Submit")
    )

    form2 <- tags$form(
      action = "/multipart-form-data",
      method = "POST",
      enctype = "multipart/form-data",
      tags$h4("multipart/form-data:"),
      tags$label(`for` = "email", "Email"),
      tags$input(id = "email", name = "email", value = "[e-mail]"),
      tags$label(`for` = "framework", "Framework"),
      tags$input(id = "framework", name = "framework", value = "ambiorix"),
      tags$label(`for` = "file", "Upload CSV file"),
      tags$input(type = "file", id = "file", name = "file", accept = ".csv"),
      tags$label(`for` = "file2", "Upload xlsx file"),
      tags$input(type = "file", id = "file2", name = "file2", accept = ".xlsx"),
      tags$button(type = "submit", "Submit")
    )

    tagList(form1, form2)
  }

  home_get <- function(req, res) {
    html <- tagList(
      page_links(),
      tags$h3("hello, world!"),
      forms()
    )

    res$send(html)
  }

  home_post <- function(req, res) {
    body <- parse_json(req)
    # print(body)

    response <- list(
      code = 200L,
      msg = "hello, world"
    )
    res$json(response)
  }

  url_form_encoded_post <- function(req, res) {
    body <- parse_form_urlencoded(req)
    # print(body)

    list_items <- lapply(
      X = names(body),
      FUN = function(nm) {
        tags$li(
          nm,
          ":",
          body[[nm]]
        )
      }
    )
    input_vals <- tags$ul(list_items)

    html <- tagList(
      page_links(),
      tags$h3("Request processed"),
      input_vals
    )

    res$send(html)
  }

  multipart_form_data_post <- function(req, res) {
    body <- parse_multipart(req)

    list_items <- lapply(
      X = names(body),
      FUN = function(nm) {
        field <- body[[nm]]

        # if 'field' is a file, parse it & print on console:
        is_file <- "filename" %in% names(field)
        is_csv <- is_file && identical(field[["content_type"]], "text/csv")
        is_xlsx <- is_file &&
          identical(
            field[["content_type"]],
            "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
          )

        if (is_file) {
          file_path <- tempfile()
          writeBin(object = field$value, con = file_path)
          on.exit(unlink(x = file_path))
        }

        if (is_csv) {
          # print(read.csv(file = file_path))
        }

        if (is_xlsx) {
          # print(readxl::read_xlsx(path = file_path))
        }

        tags$li(
          nm,
          ":",
          if (is_file) "printed on console" else field
        )
      }
    )
    input_vals <- tags$ul(list_items)

    html <- tagList(
      page_links(),
      tags$h3("Request processed"),
      input_vals
    )

    res$send(html)
  }

  about_get <- function(req, res) {
    html <- tagList(
      page_links(),
      tags$h3("About Us")
    )
    res$send(html)
  }

  contact_get <- function(req, res) {
    html <- tagList(
      page_links(),
      tags$h3("Get In Touch!")
    )
    res$send(html)
  }

  app <- Ambiorix$new(port = 5000L)

  app$
    get("/", home_get)$
    post("/", home_post)$
    get("/about", about_get)$
    get("/contact", contact_get)$
    post("/url-form-encoded", url_form_encoded_post)$
    post("/multipart-form-data", multipart_form_data_post)

  app$start()
}